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Vapor Lock after cruising through the channel

asa400ex

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So with these hot temps my boat seems to be vapor locking after going through the channel. Does RDP have any Suggestions? I can always open the hatch but was thinking about adding a second blower. One to push air in and the lower blower to pull it out. The problem is all the hot air is at the top.

What do you all think?

Thanks in advance. [emoji1303]


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t&y

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In the heat I leave the hatch cracked when beached or slow cruising. That has solved the problem without anything else needed. Adding a second blower might not be a bad idea.
 

RiverDave

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So you are rubbing the blower currently at idle?

what motor? Older Merc?
 

Shlbyntro

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So you are rubbing the blower currently at idle?

what motor? Older Merc?


Agreed. If older Merc with the gen2 coolfuel it is a known problem and there is a service bulletin for it recommending the addition of a boost pump kit.

Merc boost pump kit # 861155A12. has everything you need.

That being said, its usually a good idea to do the hp pump at the same time
 
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Devious_Chris

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So with these hot temps my boat seems to be vapor locking after going through the channel. Does RDP have any Suggestions? I can always open the hatch but was thinking about adding a second blower. One to push air in and the lower blower to pull it out. The problem is all the hot air is at the top.

What do you all think?

Thanks in advance. [emoji1303]


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What engine are you running??


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Outdrive1

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What engine are you running??


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He’s running an older 454mag with VST system.

Take the boat to Barrett or another shop and have them update it to the cool fuel system. It will be money well spent. Those motors are a pain in the ass.


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dnewps

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I am very familiar with this...if carbed motor...several wood clothing pins on the metal fuel line. If EFI...a wood block in between the fuel pump and block. Your problem is heat soak. Cracking the hatch is minimal.
 

Shlbyntro

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He’s running an older 454mag with VST system.

Take the boat to Barrett or another shop and have them update it to the cool fuel system. It will be money well spent. Those motors are a pain in the ass.


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I honestly would prefer a proper working VST system over the gen2 Cool Fuel if I had the choice. They are much less prone to vapor lock. Parts are starting to get harder to find for them though
 

Outdrive1

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I honestly would prefer a proper working VST system over the gen2 Cool Fuel if I had the choice. They are much less prone to vapor lock. Parts are starting to get harder to find for them though

Honestly, Aeromotive fuel pump with a bypass regulator solves that whole program.


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sintax

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In the heat I leave the hatch cracked when beached or slow cruising. That has solved the problem without anything else needed. Adding a second blower might not be a bad idea.

i follow the same program, I do the same after running hard and coming into a NoWake
 

SBMech

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Ambient temps are not going to fix your problem. You need a retro fit like OD 1 and Shelby are recommending. You have a mechanical design fault.

Ambient temp cooling is not going to fix your problem.
 

Shlbyntro

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Honestly, Aeromotive fuel pump with a bypass regulator solves that whole program.


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Not USCG approved. No reputable mechanic would want the liability and some (including myself) would refuse to touch an engine if we saw something like that already installed on it, except to rectify it

The boost pump kit number I posted above will still work on a merc VST, but you would have to remove the mechanical low pressure fuel pump, use a block off plate or switch water pumps, and get a new flared fuel line to go from the fuel filter housing to the vst housing.

A fresh mechanical fuel pump and raw water pump assembly generally solve the vapor lock issue on the vst systems though
 
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Outdrive1

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Not USCG approved. No reputable mechanic would want the liability and some (including myself) would refuse to touch an engine if we saw something like that already installed on it, except to rectify it

No reputable mechanic? GTFOH. [emoji849]. Every aftermarket EFI or Whippled motor on the planet is set up with a return/bypass regulator. I hope you turn everything away that scares you.


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Shlbyntro

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No reputable mechanic? GTFOH. [emoji849]. Every aftermarket EFI or Whippled motor on the planet is set up with a return/bypass regulator. I hope you turn everything away that scares you.


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500+ hp motors play by different rules in the boat world. Were not talking about one of those right now, or at least I thought??!
 

mswasey

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I chased this issue a couple of years ago on my ‘99 500efi. The band-aid is to run non-ethanol gas, no vapor lock. My permanent fix was I added a Holley electric pump just outside the fuel tank, been working great ever since.
 

Racey

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Honestly, Aeromotive fuel pump with a bypass regulator solves that whole program.


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Yep, although i recommend a Bosch 044 pump, they are way more reliable long term.

Bypass regulator with a flow through rail fixes it guaranteed. The problem is the merc motors of that era had dead headed fuel rails, the only exit from the rail is through the injector, so at idle there is very little movement through it giving the fuel plenty of time to sit there and reach a boiling point where it turns to vapor. A flow through rail solves that 100% done deal.
 

sintax

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Yep, although i recommend a Bosch 044 pump, they are way more reliable long term.

Bypass regulator with a flow through rail fixes it guaranteed. The problem is the merc motors of that era had dead headed fuel rails, the only exit from the rail is through the injector, so at idle there is very little movement through it giving the fuel plenty of time to sit there and reach a boiling point where it turns to vapor. A flow through rail solves that 100% done deal.

even for a layman like myself, this makes total sense.
 

DaveH

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Yep, although i recommend a Bosch 044 pump, they are way more reliable long term.

Bypass regulator with a flow through rail fixes it guaranteed. The problem is the merc motors of that era had dead headed fuel rails, the only exit from the rail is through the injector, so at idle there is very little movement through it giving the fuel plenty of time to sit there and reach a boiling point where it turns to vapor. A flow through rail solves that 100% done deal.
oh and the 044 costs way less, much quieter, smaller and uses less power.

i have done this very mod with success and isnt a big deal to do.
 

Shlbyntro

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20200709_164614.jpg



See this guys, this is a big fucking no no! This engine literally just pulled out of a Fountain up at the shop today. I have seen the aftermath of far too many stuck throttles and the aftermath of poor fuel system mods. A friend of mine who works on the lake was ejected from the back of a houseboat 2 seasons ago when a fuel leak from a generator ignited in the engine room. He was lucky to come away with only minor injuries, others on the boat had some more severe ones. It is worth the couple extra dollars for the marine certified factory kits when it comes to the safety of you and that of your family and friends.

That is why I dont do it, and I dont work on them. I dont want my name ever associated with those events in any way.
 

28Eliminator

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View attachment 897433


See this guys, this is a big fucking no no! This engine literally just pulled out of a Fountain up at the shop today. I have seen the aftermath of far too many stuck throttles and the aftermath of poor fuel system mods. A friend of mine who works on the lake was ejected from the back of a houseboat 2 seasons ago when a fuel leak from a generator ignited in the engine room. He was lucky to come away with only minor injuries, others on the boat had some more severe ones. It is worth the couple extra dollars for the marine certified factory kits when it comes to the safety of you and that of your family and friends.

That is why I dont do it, and I dont work on them. I dont want my name ever associated with those events in any way.

So what's the "Big Fucking No No" about a carburetor?... besides the custom throttle bracket..
 

Shlbyntro

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The custom throttle bracket is a biggy. This is also an automotive double pumper. Multiple vaccum ports that are capped off and not used. The rubber caps tend to deteriorate and allow vapors to escape when resting which is why only limited vacuum ports are allowed on marine carburetors. Also these carburetors have bowl vents pointed outwards as opposed to into the venturis in a marine carb allowing more vapors to escape the engine into the bilge.

Fuel injection systems are a lot more forgiving but any portion of the system under pressure (even 3psi) needs to be connected via flare or compression style fittings. Barbed fittings are highly illegal in this portion of fuel systems in boats unless you have an uscg exemption sticker on the vessel (you can see this on a lot of carbureted pwcs). When using electric fuel pumps, having marine certification for leak and ignition protection should be a must in everyone's eyes.

Many (but not all)safety and emissions restrictions only apply up to 499.9hp but larger companies like Mercury still adhere to the safety requirements of lesser motors in their higher hp offerings out of a liability standpoint.






Where I come from: it's not worth risking ones safety over $200. As a mechanic, I wont touch someone else's work that even has the potential to be an unsafe repair or mod. Also as a mechanic, once you touch it, you own it; you will be married to that engine forever and every problem it ever has from that point forward, in the eyes of the customer is your fault.

Call me a scared pussy ass mechanic all you want, but I have worked far too hard for my shit to potentially be responsible for someone's harm or put it all at risk to save someone I dont know $200, and with a 6 week backlog I think I can afford to decline to work on high risk boats.
 

SBMech

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The custom throttle bracket is a biggy. This is also an automotive double pumper. Multiple vaccum ports that are capped off and not used. The rubber caps tend to deteriorate and allow vapors to escape when resting which is why only limited vacuum ports are allowed on marine carburetors. Also these carburetors have bowl vents pointed outwards as opposed to into the venturis in a marine carb allowing more vapors to escape the engine into the bilge.

Fuel injection systems are a lot more forgiving but any portion of the system under pressure (even 3psi) needs to be connected via flare or compression style fittings. Barbed fittings are highly illegal in this portion of fuel systems in boats unless you have an uscg exemption sticker on the vessel (you can see this on a lot of carbureted pwcs). When using electric fuel pumps, having marine certification for leak and ignition protection should be a must in everyone's eyes.

Many (but not all)safety and emissions restrictions only apply up to 499.9hp but larger companies like Mercury still adhere to the safety requirements of lesser motors in their higher hp offerings out of a liability standpoint.






Where I come from: it's not worth risking ones safety over $200. As a mechanic, I wont touch someone else's work that even has the potential to be an unsafe repair or mod. Also as a mechanic, once you touch it, you own it; you will be married to that engine forever and every problem it ever has from that point forward, in the eyes of the customer is your fault.

Call me a scared pussy ass mechanic all you want, but I have worked far too hard for my shit to potentially be responsible for someone's harm or put it all at risk to save someone I dont know $200, and with a 6 week backlog I think I can afford to decline to work on high risk boats.

I see it a lot. All I do is recommend that they repair the system properly if I am working on something fucked up. If they won't, I pass.

I don't think anyone will judge you on the rules you have to follow to keep your certifications.

I kick shit down the road a few times a year, mostly for smog crap, they want me to do dirty shit, and I refuse.
 

Outdrive1

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The custom throttle bracket is a biggy. This is also an automotive double pumper. Multiple vaccum ports that are capped off and not used. The rubber caps tend to deteriorate and allow vapors to escape when resting which is why only limited vacuum ports are allowed on marine carburetors. Also these carburetors have bowl vents pointed outwards as opposed to into the venturis in a marine carb allowing more vapors to escape the engine into the bilge.

Fuel injection systems are a lot more forgiving but any portion of the system under pressure (even 3psi) needs to be connected via flare or compression style fittings. Barbed fittings are highly illegal in this portion of fuel systems in boats unless you have an uscg exemption sticker on the vessel (you can see this on a lot of carbureted pwcs). When using electric fuel pumps, having marine certification for leak and ignition protection should be a must in everyone's eyes.

Many (but not all)safety and emissions restrictions only apply up to 499.9hp but larger companies like Mercury still adhere to the safety requirements of lesser motors in their higher hp offerings out of a liability standpoint.






Where I come from: it's not worth risking ones safety over $200. As a mechanic, I wont touch someone else's work that even has the potential to be an unsafe repair or mod. Also as a mechanic, once you touch it, you own it; you will be married to that engine forever and every problem it ever has from that point forward, in the eyes of the customer is your fault.

Call me a scared pussy ass mechanic all you want, but I have worked far too hard for my shit to potentially be responsible for someone's harm or put it all at risk to save someone I dont know $200, and with a 6 week backlog I think I can afford to decline to work on high risk boats.

Why not fix their problems and make their boat safe?


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Outdrive1

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Same reason it got done the wrong way in the first place. Someone wanted it done cheap and didn’t want to pay to have it done right. :)

Well those you can kick down the road. [emoji106]


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28Eliminator

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The custom throttle bracket is a biggy. This is also an automotive double pumper. Multiple vaccum ports that are capped off and not used. The rubber caps tend to deteriorate and allow vapors to escape when resting which is why only limited vacuum ports are allowed on marine carburetors. Also these carburetors have bowl vents pointed outwards as opposed to into the venturis in a marine carb allowing more vapors to escape the engine into the bilge.

Fuel injection systems are a lot more forgiving but any portion of the system under pressure (even 3psi) needs to be connected via flare or compression style fittings. Barbed fittings are highly illegal in this portion of fuel systems in boats unless you have an uscg exemption sticker on the vessel (you can see this on a lot of carbureted pwcs). When using electric fuel pumps, having marine certification for leak and ignition protection should be a must in everyone's eyes.

Many (but not all)safety and emissions restrictions only apply up to 499.9hp but larger companies like Mercury still adhere to the safety requirements of lesser motors in their higher hp offerings out of a liability standpoint.






Where I come from: it's not worth risking ones safety over $200. As a mechanic, I wont touch someone else's work that even has the potential to be an unsafe repair or mod. Also as a mechanic, once you touch it, you own it; you will be married to that engine forever and every problem it ever has from that point forward, in the eyes of the customer is your fault.

Call me a scared pussy ass mechanic all you want, but I have worked far too hard for my shit to potentially be responsible for someone's harm or put it all at risk to save someone I dont know $200, and with a 6 week backlog I think I can afford to decline to work on high risk boats.

I'm well aware of the differences between a Marine carb and an automotive one, I was just curios about what you were seeing in the PICTURE you posted ;).... but thanks for the in-depth and detailed 5 paragraphs on Marine fuel system requirements/specifications as well as clarifying for everyone your obvious high standing in the Marine Industry.
 

Shlbyntro

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I'm well aware of the differences between a Marine carb and an automotive one, I was just curios about what you were seeing in the PICTURE you posted ;).... but thanks for the in-depth and detailed 5 paragraphs on Marine fuel system requirements/specifications as well as clarifying for everyone your obvious high standing in the Marine Industry.

I dont know about high standing, but high standards, I'll admit to.
 

EBT531

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I chased this issue a couple of years ago on my ‘99 500efi. The band-aid is to run non-ethanol gas, no vapor lock. My permanent fix was I added a Holley electric pump just outside the fuel tank, been working great ever since.

Was your stalling or? My 500efi stalled after a long idle and i had to throttle to get it refired. I'm wondering if thats what it was
 

mswasey

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Was your stalling or? My 500efi stalled after a long idle and i had to throttle to get it refired. I'm wondering if thats what it was
Mine ran fine, even at idle, until I shut it off and let it sit for a while in the hot summer days. Then when I would go to start it, no start. I’d have to ice the fuel lines or let it sit longer, then it would start and run fine again.
 

Shrub Lurker

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Yep, although i recommend a Bosch 044 pump, they are way more reliable long term.

Bypass regulator with a flow through rail fixes it guaranteed. The problem is the merc motors of that era had dead headed fuel rails, the only exit from the rail is through the injector, so at idle there is very little movement through it giving the fuel plenty of time to sit there and reach a boiling point where it turns to vapor. A flow through rail solves that 100% done deal.
Might you have a diagram or list of parts? I have one of these and want to head off issues prior to having issues. Thanks
 

rivermobster

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I'm well aware of the differences between a Marine carb and an automotive one, I was just curios about what you were seeing in the PICTURE you posted ;).... but thanks for the in-depth and detailed 5 paragraphs on Marine fuel system requirements/specifications as well as clarifying for everyone your obvious high standing in the Marine Industry.

I thought he was talking about using a 2x4 instead of wheel chocks...

*shrug*
 

Shlbyntro

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Might you have a diagram or list of parts? I have one of these and want to head off issues prior to having issues. Thanks

Please refer to the kit number I posted above. It is about $600 but includes everything you need and is the cleanest install kit you can find, not to mention, 100% legal. It is well worth the money.

If we are talking about a VST system, please pm me and I will advise on multiple future courses of action with part numbers
 

asa400ex

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Agreed. If older Merc with the gen2 coolfuel it is a known problem and there is a service bulletin for it recommending the addition of a boost pump kit.

Merc boost pump kit # 861155A12. has everything you need.

That being said, its usually a good idea to do the hp pump at the same time

Thank you for the info.

How does this kit work? Does it just return the unused fuel differently not allowing it to get hot? I was assuming a kit would use the lake water to cool.


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Shlbyntro

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It literally bolts to and is plumbed into the already existing fuel filter housing on the starboard side of the engine just like what can be seen on the 1st generation of Merc 496s.

It works by using a highly efficient, high vacuum and low pressure electric fuel pump to feed the already existing high pressure fuel pump mounted underneath the port motormount through the fuel filter assembly and it comes with a plug and play wiring harness that plugs right into the existing engine wiring harness that feeds the cool fuel pump. It also comes with all the plumbing fittings that you need to do the update as well as a high flow inline filter to protect the new boost pump.

20200718_151511.jpg
20200718_151435.jpg
 
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buck35

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Please refer to the kit number I posted above. It is about $600 but includes everything you need and is the cleanest install kit you can find, not to mention, 100% legal. It is well worth the money.

If we are talking about a VST system, please pm me and I will advise on multiple future courses of action with part numbers

I'm sure I'm not the only VST owner here . If there is a good fix , please post up!
I as well have learned to ice Down the tank and line to get running after a shutdown on a hot day.
95 502 gen V.
 

Shlbyntro

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If you have a vst motor and your fuel filter is mounted on the front of the motor and not on the side like on the newer gen2 cool fuel, use this kit that mounts the pump to the bulk head instead of the engine.

You will also need to remove and block off the old mechanical fuel pump.

Screenshot_20200718-152211_Chrome.jpg


You will also need to purchase this fuel line to go from the fuel filter assembly to the vst tank. Sierra #18-8115. The are a few different lengths of this fuel line so make sure to measure and order the correct one but it is flexible and somewhat forgiving if you order one that is slightly longer than you need.
Screenshot_20200718-152732_Chrome.jpg
 
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Shlbyntro

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In both cases I highly recommend replacing the high pressure pumps at the same time as adding the boost pumps, age and vapor locking over time could have put them in a weakened state. Change the needle and seat in the vst tanks as well.

The vsts are far less prone to vapor locking unless being caused by a pre existing condition in almost every case. I try to guide my customers into rebuilding the vst tank and replacing both the mechanical and electric fuel pumps as well as replacing the the raw water pump that drives the mechanical fuel pump in most of the Merc VST applications. But if you do elect go the route of the electric boost pump do make sure you still keep oil in the raw water pump where the mechanical fuel pump used to be or replace your raw water pump with the version that does not have the mechanical fuel pump boss.
 
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