Engine Help. Vapor Lock??

[Supra_Jeff]

Hello everyone.... I hope someone might be able to tell me what is wrong with my boat. It has happend the last 2 days I have been out on the water. Temps here are at about 100 right now. The boat has no problem starting right up in the morning or when we are boarding. The problem starts after I have been going for about 4 hours on the water. If we anchor up and sit for any length of time (over an hour) and try to restart it, the boat just chokes itself out or has a very hard time ideling and will then just die. It almost sounds flooded everytime. We let it sit everytime (more than 30min) and try to restart. I pump the throttle to get fresh fuel in. After a long process it will fire back up. Once we are going again, the boat is fine. I think it is vapor lock, but just wanted to make sure. Also, if that is the case, what is the best action to take to solve this problem.

I was also hoping someone could recommend a good place to get my boat worked on in case it needs to go in. I live in NW IL. I was just wondering where everyone takes their boats if anyone was close to me.

Thank you for all of your help,


Jeff

[docdrs]

you can pour lake water over your fuel pump to cool it, you can open your hatch when you stop(prevent heat build up in engine compartment), you can add marine stabil to your gas if you have been using ethanol enhanced fuel, you can add a second fuel pump close to the gas tank. It would be nice to know what boat and motor you have

[DAFF]

Perhaps your float in the carb is set a tad high. When you sit the fuel pours down the carb resulting in the run rich start up. I would pull the bowl and look for some debris or issues with the fuel pin.

[Supra_Jeff]

Thanks for the help. I have a 2007 Supra Launch 20ssv. It has a Indmar Engine.

[hgvandy]

I have a 2006 Moomba Mobius LSV with an Indmar engine as well. Mine did the same thing and the first time it happened to me, I was freaking out. It most definitely sounds like vapor lock. We switched to fuel without ethanol and it has solved our problem completely. If it is really hot, I still do open the hatch and pouring water on the fuel pump has worked every time before I finally switched to ethanol free gas. docdrs is right on with everything said above. Good luck!

[DAFF]

I wonder if a second pump closer to the tank would help by pushing fuel towards the engine mounted pump and eliminating the air locked section. Or perhaps moving the fuel pump to a cooler more vented location.

[docdrs]

Vapour lock occurs when the fuel in the pump reaches a temperature that is changes from liquid to vapour. The pump cannot pump vapour and the more you run it at this point the hotter it will get. You have to find a way to cool the fuel in the pump back to liquid. Cool the pump externally and eventually the inside will cool and the vapour return to liquid. Putting a pump in the gas tank keeps the pump cool or as above a remote pump lower than the tank or same level should in theory have less chance of heating up like the one beside the motor. opening the hatch on a hot day also lets the heat from the motor (heat sink when stopped after being run on a hot day) escape from the compartment keeping the temp lower.

[tg0824SSVGG]

I have a 2008 - it's happened to me ONCE ... I had to do the water on the primary pump trick - good thing I had read about this. It happened on a VERY hot day, and we sat without opening the engine compartment. I was 50 miles from NOWHERE with nobody around ... and, I don't know where you have an option of not using fuel with ethanol, but ALL of the fuel where I boat has the crap in it. My boat already has 2 pumps --

[docdrs]

If there is lots of pressure in the system there may be no demand placed on the remote secondary pump to turn it on. I believe the fuel rails have a pressure relief valve you can press to relieve the vapour pressure and get the second pump flowing in instances with 2 pumps. Also , marine stabil will help reduce the vaporization point and minimize vapour lock problems

[tg0824SSVGG]

Doc, Never heard of the pressure relief - marine stabil is expensive! (especially when gas is $5/gallon + ) - but perhaps not worse than sitting not being able to start.
Any idea where this relief valve might be? It's finally raining here VERY HARD - might actually put out the wildfire, so I can't go out and look.
Todd

[tg0824SSVGG]

ftp://ftp2.indmar.us/Manuals/Service Manuals/EFI Manuals/Service Manual MEFI 4/Sect 3 Fuel Metering System.pdf -- page 7 describes relief valve - says you need a fuel pressure gauge - but it looks to be a schraeder valve, so maybe just like you would a bicycle tire -- but fuel (or at least vapor) would come out - so this could be nasty ..

Thanks Doc!

Fuel Pressure Relief Procedure
Tool Required:
J 34730-1, Fuel Pressure Gauge
Important
• Refer to manufacturer’s warnings and cautions before
proceeding.
1. Disconnect negative battery cable to avoid possible fuel
discharge if an accidental attempt is made to start the
engine.

2. Loosen fuel filler cap to relieve any tank vapor pressure.
3. Connect fuel pressure gauge J 34730-1 to fuel pressure
connector assembly. Wrap a shop towel around fitting
while connecting the gauge to avoid any spillage.
4. Install bleed hose into an approved container and open
valve to bleed system pressure. Fuel connections are
now safe for servicing.
5. Drain any fuel remaining in the gauge into an approved
container.

[docdrs]

Doc, Never heard of the pressure relief - marine stabil is expensive! (especially when gas is $5/gallon + ) - but perhaps not worse than sitting not being able to start.
Any idea where this relief valve might be? It's finally raining here VERY HARD - might actually put out the wildfire, so I can't go out and look.
Todd

Mrine stabil up here is $5 and it treats 300 litres or ????????? ~70 gal ....so not that expensive

[docdrs]

ftp://ftp2.indmar.us/Manuals/Service Manuals/EFI Manuals/Service Manual MEFI 4/Sect 3 Fuel Metering System.pdf -- page 7 describes relief valve - says you need a fuel pressure gauge - but it looks to be a schraeder valve, so maybe just like you would a bicycle tire -- but fuel (or at least vapor) would come out - so this could be nasty ..

Thanks Doc!





Just put a cloth/paper towels over the valve/ area when you do it.