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Vapor Lock


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Has anyone experienced this???? After sitting for a while the boat will not always restart.. Does not do it all the time... When the engine cranks it sounds like it wants to start but will not.. Bu is running great other than this.. I changed the fuel filter. check pump and seems to be operating fine and not cavitating... My other options are to replace the lines and pump... Was wondering if anyone has heard of this.........

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i had a carburated 1985 mercruiser with a similar problem - when it was extremely hot weather (high 90's), the boat would simply start losing power. i could idle and that was about it. i would have to shut it down, open the cover and just sit for about 30 minutes. i believe the issue was because the fuel line ran from the pump across and around the engine block to the carb intake, probably the hottest part of the engine. the fuel would boil in the line and not make it into the carburator.

I solved the problem by putting pipe insulation around the fuel line. prior to that, i had replaced the fuel pump, fuel filter and tried other tricks.

i dont know if this will help you, but it is a cheap solution if it works. I bought the insulation at home depot (black, high density foam, split down one side) and attached it with small zip-ties.

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I had something like this on a 94 Prostar 205 years ago. MC & Indmar denied that it could happen with EFI (even though the TBI was nothing more than a gloried computer controlled carb). But supposedly the fact that the fuel system is pressurized, it wouldn't happen. The only time it ever did it with me was on a hot day, when the engine was running hot (like after idling around for a while), then I'd shut it down & it wouldn't re-start for 30 minutes or more.

In the end the fix was a fuel line insulation kit that I bought at Skidim.com for like $13. You could probably make it even easier.

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I had something like this on a 94 Prostar 205 years ago. MC & Indmar denied that it could happen with EFI (even though the TBI was nothing more than a gloried computer controlled carb). But supposedly the fact that the fuel system is pressurized, it wouldn't happen. The only time it ever did it with me was on a hot day, when the engine was running hot (like after idling around for a while), then I'd shut it down & it wouldn't re-start for 30 minutes or more.

In the end the fix was a fuel line insulation kit that I bought at Skidim.com for like $13. You could probably make it even easier.

+1 for the fuel line insulation........automotive industry has done this also.

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I will try insulation next year. Untill last episode, I was unsure of exact area of trouble. Some said fuel rail some said pump. Looks to be heat in pump in my case as it takes 30 to 40 minutes to get it running again if I dont wrap pump in cold towel.

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I have had the same problem. Talked to Indmar the other day and they have a fuel pump kit than can be installed. The pump kit #S495137 cost $240.00. I did not buy one yet. My boating season is over for this year. I also talked to the dealer where I got the boat. He said to take the fuel pump clamp off and put pop cycle sticks where the the rubber tape is. That will help dissipate the heat. I have not tried it yet but will next summer. What I did try the last coupl of times I went out this fall was to take the fuel pump off the bracket and leave it hang and wrapped it with insulation I did not have any problems then but then again it was not as hot out. Hope this help. Plus be aware your drive plate might go out. If you start getting noise at the rear of the engine inside the bell housing. I had 295 hours on my 2005 LXI and it went out. Seems to be a problem around this year of boat. Good luck Dave

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I have had the same problem. Talked to Indmar the other day and they have a fuel pump kit than can be installed. The pump kit #S495137 cost $240.00. I did not buy one yet. My boating season is over for this year. I also talked to the dealer where I got the boat. He said to take the fuel pump clamp off and put pop cycle sticks where the the rubber tape is. That will help dissipate the heat. I have not tried it yet but will next summer. What I did try the last coupl of times I went out this fall was to take the fuel pump off the bracket and leave it hang and wrapped it with insulation I did not have any problems then but then again it was not as hot out. Hope this help. Plus be aware your drive plate might go out. If you start getting noise at the rear of the engine inside the bell housing. I had 295 hours on my 2005 LXI and it went out. Seems to be a problem around this year of boat. Good luck Dave

[/q Rockon.gifRockon.gif :Rockon:uote]

Thanks for all the info.. Indmar must not have had the kit when i talked to them.. Drive plate?? I'm new to inboards i was an IO junky before.. I did have to re seal the plate above my drive shaft.. It was leaking water.. I am also done for the year.. I'll look into your tips and keep ya posted if i here anything else

jeff

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Soaking a towel in ice water or lake water then wrapping around the fuel pump works everytime for me. 5-10 minutes and it starts right up. Also, if you are running the engine hard (skiing, boarding, footin) then plan to stop and sit for a while, run the blower to ventilate the heat from the engine compartment. This helps alot. Thumbup.gif

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  • 2 weeks later...

It happened to me twice this summer but that was when the heat index was about 100+ degrees. The wet cold towel around the fuel pump solved the problem. I might try the cheaper fuel line insulation instead of the fuel pump kit. If it continues I might have to buy the fuel pump kit.

I'm wondering about the popsicle stick solution, did the mechanic mean the sticks can be used while the motor is in use to prevent vapor lock?

Sorry about my late response to this thread, I have not had much time to check lately as I have been busy with work after returning from our family vacation to Walt Disney World three weeks ago.

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It happened to me twice this summer but that was when the heat index was about 100+ degrees. The wet cold towel around the fuel pump solved the problem. I might try the cheaper fuel line insulation instead of the fuel pump kit. If it continues I might have to buy the fuel pump kit.

I'm wondering about the popsicle stick solution, did the mechanic mean the sticks can be used while the motor is in use to prevent vapor lock?

Sorry about my late response to this thread, I have not had much time to check lately as I have been busy with work after returning from our family vacation to Walt Disney World three weeks ago.

When you know the cause of a no run condition, it doesn't bother you so much when you can fix it in 10 minutes with a wet towel. The first time was a bit embarrassing to have to be towed in by a pontoon boat cause my boat wouldn't run. Hate to see any Bu behind a tow rope. Cry.gif Tow ropes belong behind the boat.

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I'm wondering about the popsicle stick solution, did the mechanic mean the sticks can be used while the motor is in use to prevent vapor lock?

from what i recall from cars growing up (my dad and uncles had a thing for old pontiacs and buicks) you attach the popsicle sticks to the fuel line - they absorb and dissipate the heat from the line. Actually what my dad used were wooden clothes line pins because they are the right size for the fuel line and easy to attach.

looked pretty funky! Biggrin.gif

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  • 6 months later...

OK, new season and same old problem. Had a good 8 mile run some at WOT, stopped and hung out for over an hour. Boat would not run again. Starts but idles rough and will not run when put in gear. 10 or 15 minutes of open hatches and wet cold towel around fuel pump and all is well. Guess I will need to try the Popsicle sticks or clothes pins. Any one have a better solution? My boat never did this at all the first 2 years, only after 10% ethanol fuel came to our area did this start.

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Anyone have any more info on the solution for this vapor locking? What could have changed from the fist 2 years of using this boat and the last 2 years. It never did this for 2 years and 300 hours of use. Started last year at the beginning of the season.

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MalibuNation
Anyone have any more info on the solution for this vapor locking? What could have changed from the fist 2 years of using this boat and the last 2 years. It never did this for 2 years and 300 hours of use. Started last year at the beginning of the season.

I have a 2003 LS/1 and never had vapor lock until last year and had it 3 times and 2 times it wasn't super hot out ... was wondering if it's a new gas mixture.

Edit: I pretty much never shut the engine off ... it's go go go. If I want to shut it down for awhile I'm going to let it idle for a couple of minutes and if possible do this is a shady part of the lake where the water is cooler and then open the lid to my engine and hopefully keep the boat in the shade and / or wind.

Edited by MalibuNation
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