Thunderbolt IV Need Help

[Lumpy]

Old school set up. 95 Hallett 270 with 509 B&m 420 Mega blower. TB IV with a V6 Module. Ran all the test and concluded with a bad Ignition Sensor in the distributor. Replaces sensor, cap rotor and wires. Still no spark. Dug a little
deeper...no dice. All voltage test are good including the coil. Ran great in Havi a couple of weeks ago with out a problem. Went to fire it up at home a week later and nothing.:grumble:

 

[LHC Kirby]

Did you try a different prop?

 

[Lumpy]

Did you try a different prop?

Yup....fresh blinker fluid and piston return brings too.

 

[4Waters]

Well there's your problem you didn't replace the muffler bearing.

 

[4Waters]

Is thunder bolt IV basically dura spark, I've never seen it but the pics I've seen online it looks like a dura spark module.

 

[boatdoc55]

Does it have a dead man switch that maybe has failed???

 

[Havasu Catman]

Tunderbolt IV and V are very reliable systems. I bet it is something else in the system. Start testing voltage and go from there.

 

[LHC Kirby]

Does it have a dead man switch that maybe has failed???

This ^^^^^ has gotten me twice.... and likely will again sometime in the future.

It didn't fail on me, the little clip was not in the switch.... Bonehead move.

 

[redone76]

This ^^^^^ has gotten me twice.... and likely will again sometime in the future.

It didn't fail on me, the little clip was not in the switch.... Bonehead move.

Yep! Check that kill switch. Left me floating in the Parker no wake zone till I realized I knocked it loose with my leg. Gave it a jiggle and she fired right back up

 

[Runs2rch]

Coil is good? Not sure if I missed that part.

 

[Lumpy]

yup coil is good....per the test procedure I have 12v at red/white wire and tested for activating spark by grounding green/white wire. The chart says bad ignition switch but I replaced it.
Checked all the connections on everything. Cant seem to find a kill switch anywhere. Tested the switch at the shifter and its fine. No Lanyard. Don't have a shift delay switch.:grumble:

 

[Runs2rch]

yup coil is good....per the test procedure I have 12v at red/white wire and tested for activating spark by grounding green/white wire. The chart says bad ignition switch but I replaced it.
Checked all the connections on everything. Cant seem to find a kill switch anywhere. Tested the switch at the shifter and its fine. No Lanyard. Don't have a shift delay switch.:grumble:

So you are saying you verified 12 volt at the coil? Have you verified the primary and secondary resistance of the coil?

 

[Lumpy]

Low side is 1.7 and the high side is 10.6:grumble:

 

[Fun Times]

Make sure the wiring harness connector electrical pins that connects into the TB4 ignition control module hasn't started to back out of the connector plug losing connection. Ohms and voltage test each wire possible from the module to both the coil and distributor assembly.

Be sure to carefully wiggle wires especially at the main 10 pin cannon plug at the engine to see if it helps.

Did you disconnect the Gray wire for the Tachometer on the ignition coil - side or even on the Tachometer gauge itself ?... A shorted out RPM gauge will keep the system from allowing ignition spark.

 

[Lumpy]

Did everything accept voltage/ohms test from module. I keep coming back to ignition sensor test......I strike the grn/wht wire to ground and get spark.....isnt that the last link in the chain?

 

[Fun Times]

Was the new ignition sensor OEM or aftermarket? Does the sensor have a long black ground wire that needs to run to the ground stud by the battery cable for best ground connection.

Unfortunately sensors have been know to be bad right out of the box....Maybe try ohms checking the two sensors to see if they are within a sensible ohms range of each other...Or not

http://www.ebasicpower.com/faq/MERCSB92-11.htm

Another test you might be able to try would be to use your test light connected to B+, touch the - side of the coil while cranking the engine and see if it flashes as the rotor turns... Basically the same theory like you'd be doing by hand with sticking the Green/White wire to ground to spark the coil.

Does your RPM gauge move up to around 350 RPM while cranking the engine over? The gauge should be moving if all is well.

Have you voltage tested and amperage tested your batteries? If they're low on volts or weak on cranking amps, Some of the tests done could be considered invalid. https://www.harborfreight.com/digital-automotive-battery-analyzer-66892.html

 

[Runs2rch]

Low side is 1.7 and the high side is 10.6:grumble:

Being under 11 would be a pretty weak spark if any at all. IRC 13.50 is what you want.

 

[Lumpy]

Thanks for the help guys.....pulled everything down and reconnected resulting with spark. Think a bad ground was the culprit coupled with being tired and not wearing my glasses :grumble:
Definitely will be replacing the coil after I get my fucked up firing order sorted out. Getting old sucks.

 

[Lumpy]

Possible this did not fix the initial problem. Over the last couple of years I have been plagued with a intermittent no spark issue that didn't last for more then a few hours. Almost positive this is heat related. Engine would warm up then quite. Then would start again and run all day. Next morning no spark......play and tinker then boom.....runs all day. Researched with no avail then I came across something......hiding behind the module was a wonderful little box called a "overspeed" box (rev limiter). Apparently I`m not the only one who has had issues with this little gremlin box. From what Ive read this box is very reliable but has been known to not allow spark intermittently out of the blue. This "overspeed box" wasn't all that common and is not in any trouble shooting chart that I have found for the TB IV ignition system. Generally its just module to distributor and coil. In my case its module to "overspeed box" then to distributor/coil. My plan is to bypass the gremlin box. From what I read some have just cut/spliced the wiring to bypass. Just ordered the original harness to bypass....that way its clean. Hope this helps someone else in the future.

 

[rrrr]

As someone said the TB IV is a good system. Once you get it sorted out it'll perform well and there's really no reason to replace unless you just want to spend money.

 

[Ouderkirk]