Troubleshooting Help - GM 350 Engine Dies When at Operating Temp - No Spark

[evantwheeler]

I have a '77 toyota landcruiser FJ40 that has an older 327/350 with an early Howell/Edlebrock fuel injection kit on it. I just started having an issue where the vehicle will run without issue until it gets to operating temperature, sometimes it runs for a half hour at operating temperature, and then it starts sputtering and dies. Cranks, cranks, cranks, no start. Let it sit for a half hour and it fires right up and I can drive for about 400 yards and then it dies again. I've checked fuel pressure and fuel isn't an issue. I read last night on another forum about someone having an ignition/spark issue only when the vehicle got up to operating temp. This site has a vast wealth of knowledge, so figured I'd post here and see what input I could get.

I've replaced the ignition module inside the distributor, the cap, the rotor, and the coil. Other than the distributor itself and the ecu, not sure what else I could replace that controls the spark. This issue is definitely temperature related and affects spark to all cylinders, not just one or a coupe. The temperature comment is not to say the engine is running hot at all, it certainly is not, but once things warm up, it seems that I am losing all spark somehow.

Any input on where to look to try and resolve?

 

[rivermobster]

Standalone HEI distributor?

If so, power directly from the battery and see what happens. Make Sure you use an inline fuse and at least a 10 gauge wire.

 

[mash on it]

I see you've checked for fuel pressure, but is it actually getting fuel when it quits?
Carb cleaner down the intake is an easy test.

Dan'l

 

[evantwheeler]

I see you've checked for fuel pressure, but is it actually getting fuel when it quits?
Carb cleaner down the intake is an easy test.

Dan'l

Starting fluid into throttle body and still no start when the issue is present. After it cools down, it fires right up and ides/runs fine.

 

[evantwheeler]

Standalone HEI distributor?

If so, power directly from the battery and see what happens. Make Sure you use an inline fuse and at least a 10 gauge wire.

I am pretty sure it is. There is an external coil, that looks like this:

ACDelco® - Professional™ Ignition Coil

Chevy Corvette J Engine VIN Character 1992, Professional™ Ignition Coil by ACDelco®. Visit our store and choose ACDelco products if you're looking for highly-efficient car batteries, spark plugs, air filters, wiper blades, and other repair parts.

www.carid.com

The ignition module inside the distributor looks like this, but it's just a stock O'reilley's replacement:

ACCEL 35361 ACCEL High Performance Ignition Module for GM HEI 4 Pin

This high performance HEI module provides your plugs with more spark over the stock module. The solid state electronics provide high coil out put and superior reliability. The Dwell control circuit ensures, long consistent coil charging. The current control circuit protects against coil over...

www.holley.com

So you're saying find power wire from ecu to distributor, unplug the power from ecu and install a power lead from battery to distributor? This would bypass the ecu and tell me if the issue is in the ECU?

One thing that leads me to believe it is ignition or ecu related is that the tach & the voltage gauge both go crazy bouncing up & down when it starts spitting & sputtering on it's way to dying.

Thanks for the reply!

 

[ElAzul]

Check all yore grounds based on the haywire stuff happening before it dies. Does it have a knock sensor?

 

[rivermobster]

I am pretty sure it is. There is an external coil, that looks like this:

ACDelco® - Professional™ Ignition Coil

Chevy Corvette J Engine VIN Character 1992, Professional™ Ignition Coil by ACDelco®. Visit our store and choose ACDelco products if you're looking for highly-efficient car batteries, spark plugs, air filters, wiper blades, and other repair parts.

www.carid.com

The ignition module inside the distributor looks like this, but it's just a stock O'reilley's replacement:

ACCEL 35361 ACCEL High Performance Ignition Module for GM HEI 4 Pin

This high performance HEI module provides your plugs with more spark over the stock module. The solid state electronics provide high coil out put and superior reliability. The Dwell control circuit ensures, long consistent coil charging. The current control circuit protects against coil over...

www.holley.com

So you're saying find power wire from ecu to distributor, unplug the power from ecu and install a power lead from battery to distributor? This would bypass the ecu and tell me if the issue is in the ECU?

One thing that leads me to believe it is ignition or ecu related is that the tach & the voltage gauge both go crazy bouncing up & down when it starts spitting & sputtering on it's way to dying.

Thanks for the reply!

Yep. You got it.

Sounds like you need to throw all your ignition stuff in the trash, but, let's not jump to conclusions.

Power the ignition system independently of of everything else. If it still does the same thing...

File it all in the round file and go with a ready to run Petronix distributor and matching coil.

There is no timing control coming from the EFI system, correct?

 

[mash on it]

This land cruiser originally had points on the 6 cyl. Is there a full 12v at the coil? Points generally had a ballast resistor or a resistor wire. Is the wiring still factory Toyota?

Dan'l

 

[evantwheeler]

Check all yore grounds based on the haywire stuff happening before it dies. Does it have a knock sensor?

I do not believe there is a knock sensor. This EFI retrofit system seems pretty early. It has OBD1 connector to the ECU. ECU Has a Howell sticker on it but Howell has been unresponsive and there is no literature on this system that I can find online. Intake is an edelbrock with 8 injectors.

The vehicle ran fine off & on many years (it lived in storage, I worked out of town and was never around). It did Moab in 2012 and Rubicon in 2014 without issue. It just started acting up after I bought a house and have started driving it more often since it lives where I live now. I had a no start COLD issue (separate from current issue), which was remedied with the new coil/igniter deal, cap, rotor and ignition control module. Thought I was golden and drove it around town for a couple weeks. One day drove it to work and it died on me halfway home. It took me 3 hours to drive 1.5 miles as I could drive 400 yards or so and then have to let it sit and cool for a bit and then it would start up and run fine for a minute and spit sputter and die on me again. Been parked since then and have focused efforts on other projects.

 

[evantwheeler]

Yep. You got it.

Sounds like you need to throw all your ignition stuff in the trash, but, let's not jump to conclusions.

Power the ignition system independently of of everything else. If it still does the same thing...

File it all in the round file and go with a ready to run Petronix distributor and matching coil.

There is no timing control coming from the EFI system, correct?

I hope I don't need to throw it all in the trash, it's all brand new from Oreilley's (just the cap, rotor, module, and ignitor coil)! Maybe that's why it belongs in the trash, O'reilleys ?!? This isn't a high performance rig, just a cruiser and a wheeler. I am 99% sure it needs a cam, because all it does is make more noise above 3k rpm, but it runs "fine" otherwise for my needs. It's kinda nice really because it doesn't have enough power to hurt anything but has enough power and torque to crawl over rocks well with the auto th350/Atlas 3.8 and 4.56 diff gears.

Copy on the Pertronix route if it still acts same way with ignition power independent of everything else.

Unsure if I can answer the no timing control coming from the efi system. I suspect there has to be some timing input as it needs to know when to open the injectors? It has 8 injectors like a more modern EFI system would have. Throttle body for air intake control only, no fuel metering through the throttle body.

 

[evantwheeler]

This land cruiser originally had points on the 6 cyl. Is there a full 12v at the coil? Points generally had a ballast resistor or a resistor wire. Is the wiring still factory Toyota?

Dan'l

This thing has a completely non-stock drivetrain. GM SBC with early Edlebrock/Howell fuel injection kit, th350, aftermarket transfer case. The wiring on the engine is a painless harness or maybe it was a painless harness provided with the EFI kit. It all came on the truck when I bought it from the previous owner.

I have one with the stock inline 6, and I dumped the stock distributor and ignition for fully electronic DUI setup. On fence of keeping stock carb or just going Holley Sniper EFI on that one.

Here are the pair. I don't know why I thought I needed two of them, but I really like these old cruisers.

 

[Bowtiepower00]

Is it a TBI style EFI with a external coil distributor? Like this:

If so, I’d try a new pickup sensor.

https://www.amazon.com/ACDelco-D1987-Original-Equipment-Distributor/dp/B000BYB1WQ

Or possibly you got a bad coil or module from O’riellys. Surprisingly high failure rate on their electronic stuff.

Have you tried swapping a regular coil on cap HEI?

 

[evantwheeler]

Is it a TBI style EFI with a external coil distributor? Like this:
View attachment 1013750
If so, I’d try a new pickup sensor.

https://www.amazon.com/ACDelco-D1987-Original-Equipment-Distributor/dp/B000BYB1WQ

Or possibly you got a bad coil or module from O’riellys. Surprisingly high failure rate on their electronic stuff.

Have you tried swapping a regular coil on cap HEI?

Yes, that is what the coil distributor looks like. Pickup sensor has not been replaced as I wasn't aware of this part existing or being replaceable when I was throwing parts at it previously. Will throw more parts at it and see if it works as well as trying the dedicated fused power to ignition system as suggested earlier.

I knew I should have just used AC Delco parts, but o'reilly's is 5 min from the house and I was in a pinch as she died on me cold right in the middle of my yard and didn't have a hand to push it back out of the way. Thank you for your input!

 

[rivermobster]

I hope I don't need to throw it all in the trash, it's all brand new from Oreilley's (just the cap, rotor, module, and ignitor coil)! Maybe that's why it belongs in the trash, O'reilleys ?!? This isn't a high performance rig, just a cruiser and a wheeler. I am 99% sure it needs a cam, because all it does is make more noise above 3k rpm, but it runs "fine" otherwise for my needs. It's kinda nice really because it doesn't have enough power to hurt anything but has enough power and torque to crawl over rocks well with the auto th350/Atlas 3.8 and 4.56 diff gears.

Copy on the Pertronix route if it still acts same way with ignition power independent of everything else.

Unsure if I can answer the no timing control coming from the efi system. I suspect there has to be some timing input as it needs to know when to open the injectors? It has 8 injectors like a more modern EFI system would have. Throttle body for air intake control only, no fuel metering through the throttle body.

I'm going to guess it just batch fires the injectors, based off the tach output on the distributor.

We need a wiring diagram for the EFI. Any chance you have that?

 

[evantwheeler]

I'm going to guess it just batch fires the injectors, based off the tach output on the distributor.

We need a wiring diagram for the EFI. Any chance you have that?

No wiring diagram. I’ll give Howell another try tomorrow over the phone and see if i can get someone who cares to help and hopefully the can provide something.

 

[Bowtiepower00]

Assuming the Howell setup is basically a GM TBI setup- which I think it was but it’s been almost 20 years since I was messing with TBI stuff, a good place to go on a deep dive for knowledge is:

TBI - Third Generation F-Body Message Boards

TBI - Throttle Body Injection discussion and questions. L03/CFI tech and other performance enhancements.

www.thirdgen.org

There are a couple of other subforums on thirdgen.org that might have info, but that is the main one.

There used to be a TBI section at 454ss.com but it looks like the website is gone.

 

[stoker2001]

Yes, that is what the coil distributor looks like. Pickup sensor has not been replaced as I wasn't aware of this part existing or being replaceable when I was throwing parts at it previously. Will throw more parts at it and see if it works as well as trying the dedicated fused power to ignition system as suggested earlier.

I knew I should have just used AC Delco parts, but o'reilly's is 5 min from the house and I was in a pinch as she died on me cold right in the middle of my yard and didn't have a hand to push it back out of the way. Thank you for your input!

doubt that 2wire pickup coil is intermittent..my experience with all the GM TBI stuff at work here is it has continuity (800 ohm spec) or it will be bad and show open circuit

 

[rivermobster]

No wiring diagram. I’ll give Howell another try tomorrow over the phone and see if i can get someone who cares to help and hopefully the can provide something.

See if you can get a downloadable PDF from them.

 

[evantwheeler]

See if you can get a downloadable PDF from them.

Talked with Howell, guy spent 15 mins on phone with me. They said they don't have any digital documentation of the system as it was discontinued long ago, but that the wiring is based on a 1990 Camaro with Tuned Port motor. I found a painless manual for TPI swap harnesses which I think will get me in the right direction. Howell tech said that it is looking like coil or distributor based on fluctuating tachometer symptom. I also ordered an ALDL cable so I can plug my laptop into the computer and get any codes and also maybe do some data logging if I can get the thing to repeat the issue while plugged in. Thanks for all the pointers so far!

 

[rivermobster]

Talked with Howell, guy spent 15 mins on phone with me. They said they don't have any digital documentation of the system as it was discontinued long ago, but that the wiring is based on a 1990 Camaro with Tuned Port motor. I found a painless manual for TPI swap harnesses which I think will get me in the right direction. Howell tech said that it is looking like coil or distributor based on fluctuating tachometer symptom. I also ordered an ALDL cable so I can plug my laptop into the computer and get any codes and also maybe do some data logging if I can get the thing to repeat the issue while plugged in. Thanks for all the pointers so far!

I'm checking into eye surgery at the moment. I'll look at that PDF as soon as I can.

 

[evantwheeler]

I'm checking into eye surgery at the moment. I'll look at that PDF as soon as I can.

Good luck. I've been under the knife 3 times on my left eye, 1st for trauma foreign body removal, 2nd for fixing damage due to foreign body in eye, and 3rd for detached retina. All no fun. Hopefully yours is outpatient!

Please don't spend any time looking at that PDF, I'm sure you have more important things in your life! I have the means to trouble shoot, i just posted up here to use you folks as a sounding board and get ideas. When I talk out loud to myself, no one ever responds and I just look crazy!

 

[evantwheeler]

Check all yore grounds based on the haywire stuff happening before it dies. Does it have a knock sensor?

Did a little digging last night.

So it does have a knock sensor. Hasn't been replaced yet. Symptoms of a bad or faulty knock sensor are? Can I just unscrew the sensor from block and leave it plugged in to trick computer to see if knock sensor is causing me some issues?

I re-checked fuel pressure. 45-ish key on, engine off. Start up idle at 800 rpm pressure is steady at 36 psi. Touch the throttle and bumps up to 38-40psi and holds steady there up to 3k rpm. Over 3k rpm, engine does not run properly and spits sputters and backfires. This is not the issue I am trying to solve at the moment. As stated earlier, I have no issues at the moment with the 3k RPM limit as this is just a crawler and it does fine for its purpose.

I checked timing. Brought engine up to operating temperature. I unplugged the brown/black stripe single wire that is separate from harness to kill electronic advance on distributor. Initial idle timing is 6deg BTDC, which from what I have read, seems OK. Some say 8, some say 10. With electronic advance connected, timing at idle is approximately 18 deg BTDC. I don't think I have any issues with timing.

I still haven't sought out an actual color coded wiring diagram yet for the wires to the distributor, need to find that tonight and figure out which one is power from the ECU and then I can perform the test that Mobster suggested with powering straight from the ignition.

Another thing I haven't played with is the O2 sensor. On my sand car LS engine, I had a bad O2 sensor causing me some rough running troubles and I found the issue using my HPtuners software. I don't think it would kill the engine intermittently with a bad O2 sensor, but I think I will replace it just to eliminate it from the equation as an issue. It's likely 12-15 years old at this point....

A few thoughts on my rough running above 3k RPM issue that I would like to remedy in the long term:
- Based on block number (3970010), this block has a 4" bore, but came in offerings of 305 and 350, some say 327 as well.... Having never opened it up, I have no clue on actual bore or stroke. The displacement of the engine MAY be off for the size of my injectors and program in the computer. I assume no way to tell without tearing into it huh?
- I could have a bad camshaft. Any way to tell other than just pulling the damn thing out?
- I could have head issue. I bought a leak down tester and a compression tester (both OTC brand) and should have them in hand tomorrow so I can do a health check on the heads and cylinders over the weekend.

- Is there any way to tune this computer myself, or will I need some custom chip burning equipment? The computer is a Serv No 01227730. I have the correct ALDL cable coming by Friday so I can hook my laptop up to the computer and the guys I bought the cable from said I am getting a thumbdrive with free software to communicate with the computer. I assume it's only for real-time monitoring, not for data logging or tuning. I do have HP Tuners, but from what I understand, it doesn't work with the OBDI stuff.

 

[monkeyswrench]

Howells does standalone eprom stuff, ODBI is like an Atari 2600 compared to the LS stuff. Seen some in jeeps and such, works well, but not very easily tunable. If they stuck with the mostly GM setup, you could have a bad oil pressure sender. I think the TBI trucks used to cut the ignition feed or fuel with low oil pressure.

 

[JUSTWANNARACE]

Just delt with the same exact issue awhile ago in this. 89 K5 TBI 350.

To the T how you are describing your issue. Went and bought cap, rotor, coil, module, ect. Put all the new stuff in and same shit!! Tore it all back apart to replace all the center shit. (Stuff is still sitting on a shelf)

Called the parts store and for like $149 bought this. (Complete assembly). Told myself if that was the issue I'd upgrade to something better than "Duralast"

Put it in, fired up, and it hasn't skipped a beat since. So yes, the duralast is still in there!

 

[JUSTWANNARACE]

Just delt with the same exact issue awhile ago in this. 89 K5 TBI 350. View attachment 1014661



To the T how you are describing your issue. Went and bought cap, rotor, coil, module, ect. Put all the new stuff in and same shit!! Tore it all back apart to replace all the center shit. (Stuff is still sitting on a shelf) View attachment 1014663 View attachment 1014662


Called the parts store and for like $149 bought this. (Complete assembly). Told myself if that was the issue I'd upgrade to something better than "Duralast"
View attachment 1014664


Put it in, fired up, and it hasn't skipped a beat since. So yes, the duralast is still in there!

Hell I went through the same thing on my boat that's behind the K5 about a month ago. It had this!

Went to the parts store and bought this just to rule out the issue. Before I spent $600_$800 on new fancy shit. Fired right up and hasn't skipped a beat. Same rpm same mph and actually smoother through out the rpm range.

 

[drew_built]

If it’s similar to a GM tbi those fuel pressures sound high, research says you can run that if it has the correct size return line

make sure injector size is correct the original owner of my set up got a kit for a bbc v8,
the 02 tried leaning it out but couldn’t under load you had to ease the throttle, he got frustrated and I took it off his hands for cheap lol

The stalling sounds like your air gap on the pick up might be too big or it is going out

I have an fj40 with the original inline 6 and a GM setup, these three things solved everything

 

[rivermobster]

Good luck. I've been under the knife 3 times on my left eye, 1st for trauma foreign body removal, 2nd for fixing damage due to foreign body in eye, and 3rd for detached retina. All no fun. Hopefully yours is outpatient!

Please don't spend any time looking at that PDF, I'm sure you have more important things in your life! I have the means to trouble shoot, i just posted up here to use you folks as a sounding board and get ideas. When I talk out loud to myself, no one ever responds and I just look crazy!

Cataract surgery. Piece of cake. I now have 20-20 vision in the eye I could barely see out of. I'm stoked!

I'll print it and take a good look at it tomorrow.

 

[evantwheeler]

If it’s similar to a GM tbi those fuel pressures sound high, research says you can run that if it has the correct size return line

make sure injector size is correct the original owner of my set up got a kit for a bbc v8,
the 02 tried leaning it out but couldn’t under load you had to ease the throttle, he got frustrated and I took it off his hands for cheap lol

The stalling sounds like your air gap on the pick up might be too big or it is going out

I have an fj40 with the original inline 6 and a GM setup, these three things solved everything

It is not TBI, it is a mulitport injection system with 8 separate injectors. I think if it was TBI that the range would be 15ish psi. I doubt I will be able to get any info on the injectors. I'm making a list of questions to call Howell on Friday and ask for the same guy I talked with earlier in the week. He was very helpful.

I'm going to replace the distributor pick-up this weekend.

 

[evantwheeler]

Cataract surgery. Piece of cake. I now have 20-20 vision in the eye I could barely see out of. I'm stoked!

I'll print it and take a good look at it tomorrow.

I have a cataract and no one will do the surgery because of my past foreign body trauma. Said that its too risky, so 20/200 in the left eye it is for me until they can just start replacing whole eyeballs!

 

[evantwheeler]

Note, this is a speed density tune setup, I do not have a MAF. I think everything is controlled off of a MAP sensor. I'm going to order a map sensor as well.

 

[evantwheeler]

This is how my distributor is wired. I don't see that any of the four wires coming from my ECM would be the ones that I would want to bypass and power directly from battery. Power from battery would go to the primary coil, instead of coming from the ignition, correct @rivermobster ?

 

[rivermobster]

View attachment 1014730

This is how my distributor is wired. I don't see that any of the four wires coming from my ECM would be the ones that I would want to bypass and power directly from battery. Power from battery would go to the primary coil, instead of coming from the ignition, correct @rivermobster ?

So this is a fully integrated ignition system with timing control...

Your options are to replace the individual components or replace the whole EFI system!

All of those early ignition designs had these same heat issues..

Seems like you're on the right path....

 

[evantwheeler]

So this is a fully integrated ignition system with timing control...

Your options are to replace the individual components or replace the whole EFI system!

All of those early ignition designs had these same heat issues..

Seems like you're on the right path....

Fingers crossed. If I can't get it solved, it's getting a new engine. I'd really like to get my hands on a direct injected V6 LV3. I don't need big power. I would go 4.8 or 5.3 before going with one of the earlier 4.3 V6's though.

 

[rivermobster]

Fingers crossed. If I can't get it solved, it's getting a new engine. I'd really like to get my hands on a direct injected V6 LV3. I don't need big power. I would go 4.8 or 5.3 before going with one of the earlier 4.3 V6's though.

A 5.3 swap would be cool. Probably inexpensive too since there are 9 billion of those things in the bone yard!

Keep us posted on how this turns out.

 

[4Waters]

I didn't see anyone say check all grounds. That said check all grounds, make sure they are all clean and tight, make sure you have an engine ground (block to frame) as that is forgotten a lot.

 

[evantwheeler]

I didn't see anyone say check all grounds. That said check all grounds, make sure they are all clean and tight, make sure you have an engine ground (block to frame) as that is forgotten a lot.

Spent some hours on it last night.

Grounds are good, there are three grounds direct from battery with 1 or 2 gauge battery cable. 1. from battery to intake manifold, 2. from battery to frame, 3. from battery to body on firewall.

I adjusted timing from 6 deg BTDC to 12 deg BTDC at the recommendation of Howell. It ran horrible. Seem to start better and idle smoother, but it was getting waaaay too much fuel. Acted like it was running on 4 cylinders on any throttle off of idle because of all the fuel and you could smell it from the exhaust.

While I was adjusting the distributor for timing, I found that I could kill the engine by putting pressure on the two most rearward spark plug wire boots on top of the cap. Almost like a pressure point on a human, moderate straight downward pressure on either of these two boots and the engine would die. It was repeatable over and over and over, and it was only on those two locations. As many of you have suggested, looks like this issue is contained within the distributor, now to just figure the actual root cause. I probably would have been money ahead just doing as JUSTWANNARACE did and replace the whole dizzy. I may just do that with a large cap with integrated coil, but I'm also to the point where I'm tired of spending money on the cock sucker as between the parts and tuning stuff, I'm going to be into this thing for $400 here shortly. That's a quarter of the way to my junkyard 5.3 swap!

I was unable to get the engine to replicate the die and no restart for 20 min situation that I've encountered before. I was hoping it would act up and had planned to put my inline spark tester between the coil and the dist cap to see if coil was giving spark during the no start event, but no luck getting it to act up.

Could not get my ECU to communicate with the laptop and data logging software. I've got some emails out and hoping someone is still alive that knows how to get this ECU to talk to the computer. The guy that sold me the cable "just sells cables" and the guy that sold me the software "just sells software". Howell gave me a pointer that I may need to make a jumper on my ODB1 port to get the software to communicate with the ECM, so I'll try that tonight if I can find the right style of end connector that inserts into the plug.

 

[4Waters]

Spent some hours on it last night.

Grounds are good, there are three grounds direct from battery with 1 or 2 gauge battery cable. 1. from battery to intake manifold, 2. from battery to frame, 3. from battery to body on firewall.

I adjusted timing from 6 deg BTDC to 12 deg BTDC at the recommendation of Howell. It ran horrible. Seem to start better and idle smoother, but it was getting waaaay too much fuel. Acted like it was running on 4 cylinders on any throttle off of idle because of all the fuel and you could smell it from the exhaust.

While I was adjusting the distributor for timing, I found that I could kill the engine by putting pressure on the two most rearward spark plug wire boots on top of the cap. Almost like a pressure point on a human, moderate straight downward pressure on either of these two boots and the engine would die. It was repeatable over and over and over, and it was only on those two locations. As many of you have suggested, looks like this issue is contained within the distributor, now to just figure the actual root cause. I probably would have been money ahead just doing as JUSTWANNARACE did and replace the whole dizzy. I may just do that with a large cap with integrated coil, but I'm also to the point where I'm tired of spending money on the cock sucker as between the parts and tuning stuff, I'm going to be into this thing for $400 here shortly. That's a quarter of the way to my junkyard 5.3 swap!

I was unable to get the engine to replicate the die and no restart for 20 min situation that I've encountered before. I was hoping it would act up and had planned to put my inline spark tester between the coil and the dist cap to see if coil was giving spark during the no start event, but no luck getting it to act up.

Could not get my ECU to communicate with the laptop and data logging software. I've got some emails out and hoping someone is still alive that knows how to get this ECU to talk to the computer. The guy that sold me the cable "just sells cables" and the guy that sold me the software "just sells software". Howell gave me a pointer that I may need to make a jumper on my ODB1 port to get the software to communicate with the ECM, so I'll try that tonight if I can find the right style of end connector that inserts into the plug.

Check your fuel pump ground, your EFI ground and your ECU ground as well if separate from EFI ground

 

[lbhsbz]

Check your fuel pump ground, your EFI ground and your ECU ground as well if separate from EFI ground

I wouldn’t stop at a visual inspection/wiggle test...instead, put a load on the circuit and perform a voltage drop test on each component ground to actually prove the integrity of the circuit.

 

[rivermobster]

Spent some hours on it last night.

Grounds are good, there are three grounds direct from battery with 1 or 2 gauge battery cable. 1. from battery to intake manifold, 2. from battery to frame, 3. from battery to body on firewall.

I adjusted timing from 6 deg BTDC to 12 deg BTDC at the recommendation of Howell. It ran horrible. Seem to start better and idle smoother, but it was getting waaaay too much fuel. Acted like it was running on 4 cylinders on any throttle off of idle because of all the fuel and you could smell it from the exhaust.

While I was adjusting the distributor for timing, I found that I could kill the engine by putting pressure on the two most rearward spark plug wire boots on top of the cap. Almost like a pressure point on a human, moderate straight downward pressure on either of these two boots and the engine would die. It was repeatable over and over and over, and it was only on those two locations. As many of you have suggested, looks like this issue is contained within the distributor, now to just figure the actual root cause. I probably would have been money ahead just doing as JUSTWANNARACE did and replace the whole dizzy. I may just do that with a large cap with integrated coil, but I'm also to the point where I'm tired of spending money on the cock sucker as between the parts and tuning stuff, I'm going to be into this thing for $400 here shortly. That's a quarter of the way to my junkyard 5.3 swap!

I was unable to get the engine to replicate the die and no restart for 20 min situation that I've encountered before. I was hoping it would act up and had planned to put my inline spark tester between the coil and the dist cap to see if coil was giving spark during the no start event, but no luck getting it to act up.

Could not get my ECU to communicate with the laptop and data logging software. I've got some emails out and hoping someone is still alive that knows how to get this ECU to talk to the computer. The guy that sold me the cable "just sells cables" and the guy that sold me the software "just sells software". Howell gave me a pointer that I may need to make a jumper on my ODB1 port to get the software to communicate with the ECM, so I'll try that tonight if I can find the right style of end connector that inserts into the plug.

Couple things...

Did you unplug the Set Timing Connector before making any timing adjustments?

That pressure on the boot thing is nuts...

Pull those wires off the cap and take a nice clear pic looking into the wire end. Very strange.

Have you Verified your timing order is correct?

 

[JUSTWANNARACE]

Spent some hours on it last night.

Grounds are good, there are three grounds direct from battery with 1 or 2 gauge battery cable. 1. from battery to intake manifold, 2. from battery to frame, 3. from battery to body on firewall.

I adjusted timing from 6 deg BTDC to 12 deg BTDC at the recommendation of Howell. It ran horrible. Seem to start better and idle smoother, but it was getting waaaay too much fuel. Acted like it was running on 4 cylinders on any throttle off of idle because of all the fuel and you could smell it from the exhaust.

While I was adjusting the distributor for timing, I found that I could kill the engine by putting pressure on the two most rearward spark plug wire boots on top of the cap. Almost like a pressure point on a human, moderate straight downward pressure on either of these two boots and the engine would die. It was repeatable over and over and over, and it was only on those two locations. As many of you have suggested, looks like this issue is contained within the distributor, now to just figure the actual root cause. I probably would have been money ahead just doing as JUSTWANNARACE did and replace the whole dizzy. I may just do that with a large cap with integrated coil, but I'm also to the point where I'm tired of spending money on the cock sucker as between the parts and tuning stuff, I'm going to be into this thing for $400 here shortly. That's a quarter of the way to my junkyard 5.3 swap!

I was unable to get the engine to replicate the die and no restart for 20 min situation that I've encountered before. I was hoping it would act up and had planned to put my inline spark tester between the coil and the dist cap to see if coil was giving spark during the no start event, but no luck getting it to act up.

Could not get my ECU to communicate with the laptop and data logging software. I've got some emails out and hoping someone is still alive that knows how to get this ECU to talk to the computer. The guy that sold me the cable "just sells cables" and the guy that sold me the software "just sells software". Howell gave me a pointer that I may need to make a jumper on my ODB1 port to get the software to communicate with the ECM, so I'll try that tonight if I can find the right style of end connector that inserts into the plug.

Some of those old EFI ECU's will not communicate with any modern laptop no matter the software. I've had to buy a few old school IBM thinkpads off ebay because that was the only computer I could find that would communicate with the ecu

 

[evantwheeler]

Well I got all my parts in Friday, but they are still in the box. I am being sent to NY for a project, be gone about a month or so, so this thing got put under a cover and parked. To be continued when I return home later this summer. Thanks for all the input.

@rivermobster , I had not checked the timing/firing order for plugs & wires. That is a simple thing to do for sure. I looked into the spark plug wire boots that connected to the distributor cap and couldn't see anything that looked telling as far as an issue. No corrosion or signs of arcing. I guess I could swap them with other cylinders and see if the problem follows the plug wire or if it is just based on how/where I was putting force onto the distributor.

 

[rivermobster]

Well I got all my parts in Friday, but they are still in the box. I am being sent to NY for a project, be gone about a month or so, so this thing got put under a cover and parked. To be continued when I return home later this summer. Thanks for all the input.

@rivermobster , I had not checked the timing/firing order for plugs & wires. That is a simple thing to do for sure. I looked into the spark plug wire boots that connected to the distributor cap and couldn't see anything that looked telling as far as an issue. No corrosion or signs of arcing. I guess I could swap them with other cylinders and see if the problem follows the plug wire or if it is just based on how/where I was putting force onto the distributor.

Good idea. Have fun on your trip!

 

[Bigbore500r]

I'd shitcan the ancient Howell system, slap a sniper EFI TB on there and a fresh GM HEI.

 

[Chili Palmer]

People have said check your grounds, but check your battery cables too.

 

[evantwheeler]

Couple things...

Did you unplug the Set Timing Connector before making any timing adjustments?

That pressure on the boot thing is nuts...

Pull those wires off the cap and take a nice clear pic looking into the wire end. Very strange.

Have you Verified your timing order is correct?

Finally opened the box of parts from summit that i had overnighted to me 20 months ago

Had a no start no spark condition again after the truck had sat for a few months so i pulled the dist and replaced the pickup coil. New O2, knock sensor, and MAP sensor. Also put 8 new NGKs in it. Engine runs the best it ever has now, but im still having an issue with the engine cutting out at and above 2800rpm under load. Sitting in the driveway in park i can rev up to and beyond 2800 with zero issue. Slowly opening throttle to 4k, quickly WOT to 4k, hold throttle open at 3k, engine is smooth in all situations. If i am driving though, i can only get past 2800rpm smoothly if i am very very light on the throttle. If i go WOT while driving, or even 3/4 throttle, the engine cuts out and spits and stutters and stumbles past 2800 rpm. Its will get to 4k, but its ugly getting there.

Having a hard time wrapping my head around what could cause this as it appears to be completely load sensitive. If it was component failure/issue, it would do it in the driveway in a no load scenario. Trans is a TH350, so the only communication between the engine and the trans is the kickdown cable…..

Im not going to spend a bunch of money on a toy that sits so much, so the LS swap, or new fuel injection system comments are pointless, unless someone has a cheap LV3 with a 6l80 and harness

 

[evantwheeler]

I should be in johnson valley for KOH, but i dont trust this thing enough yet…

 

[evantwheeler]

Couple things...

Did you unplug the Set Timing Connector before making any timing adjustments?

That pressure on the boot thing is nuts...

Pull those wires off the cap and take a nice clear pic looking into the wire end. Very strange.

Have you Verified your timing order is correct?

Brown wire was unplugged to set initial timing. I will say that the timing doesnt seem to change at all when that wire is reconnected and i rev the engine with the timing light on the mark…

Verified plug wires are correct.

Put the distributor into 3 different cam gear positions to make sure it was stabbed correctly. I have that right for sure.

 

[rivermobster]

Finally opened the box of parts from summit that i had overnighted to me 20 months ago

Had a no start no spark condition again after the truck had sat for a few months so i pulled the dist and replaced the pickup coil. New O2, knock sensor, and MAP sensor. Also put 8 new NGKs in it. Engine runs the best it ever has now, but im still having an issue with the engine cutting out at and above 2800rpm under load. Sitting in the driveway in park i can rev up to and beyond 2800 with zero issue. Slowly opening throttle to 4k, quickly WOT to 4k, hold throttle open at 3k, engine is smooth in all situations. If i am driving though, i can only get past 2800rpm smoothly if i am very very light on the throttle. If i go WOT while driving, or even 3/4 throttle, the engine cuts out and spits and stutters and stumbles past 2800 rpm. Its will get to 4k, but its ugly getting there.

Having a hard time wrapping my head around what could cause this as it appears to be completely load sensitive. If it was component failure/issue, it would do it in the driveway in a no load scenario. Trans is a TH350, so the only communication between the engine and the trans is the kickdown cable…..

Im not going to spend a bunch of money on a toy that sits so much, so the LS swap, or new fuel injection system comments are pointless, unless someone has a cheap LV3 with a 6l80 and harness

Holy shit!!! I had to read this whole thread to catch back up!

Almost two years?? Did you get rid of all the old fuel before you started it up?? If not, start there, and don't run it again until you do! Bad gas can cause Serious engine problems.

Replace the filter and flush everything out with fresh fuel...

Add Seafoam into the fresh fuel, and then add http://www.starbrite.com/item/star-tron-gasoline-additive
When you park it. Store it with a full tank.

Keep us posted!!!

 

[rivermobster]

Brown wire was unplugged to set initial timing. I will say that the timing doesnt seem to change at all when that wire is reconnected and i rev the engine with the timing light on the mark…

Verified plug wires are correct.

Put the distributor into 3 different cam gear positions to make sure it was stabbed correctly. I have that right for sure.

Timing doesn't change???

So at 3500rpm it's still sitting at 6 degrees??

 

[monkeyswrench]

Ok, started rereading this...being a Howell, the first thing I'd ask is what cam, and did that get figured into the program? Then I'd say check the block grounds, bare metal, direct from batt.

Does it fart and pop, or just real lazy? Real lazy, timing issues. Farting and popping, timing or valves.
What timing pointer and what harmonic balancer, are they matched? I run into that all the time with things. Shoot yourself in the foot before you start.