Engine won't start when hot

[jlemberg]

Starting last week my '06 Outback V has failed to start on 4 separate occasions. The engine will turn over fine, but will barely start to idle and die or just not catch at all. It seems to only happen when the engine is hot (recently pulled skiers/wakesurfers). However, on time yesterday it hadn't been used for hours and did it again.

If you wait 1/2 hour to an hour it usually starts up fine. Once it's started it runs perfectly. Anybody have this problem before?

[byronkoz]

carb or EFI? Fuel pump mabye fuel filter? Couple of weeks ago mine was acting simalar to yours and turned out to be inline fuel filter.

[dtlaine]

vapor lock? what's the ambient temp?

[Wake Master]

If it is EFI you need 80PSI in the fuel rail for the injectors to open. It could be, the fuel filter, fuel pump, or vapor lock. If you have not had any problems before it is probally not a vapor lock problem but you should leave the blower running the entire time the engine is running to help pull out the heat. I would start with the fuel filter if it's time to change the filter and see if this corrects the problem. I have a 07 XLV with the 340 EXT-CAT exhaust and the extra heat from the cat. converters can cause vapor lock. I had this problem and the manufactures are aware of the issue. The dealer installed a low pressure fuel pump at the tank to feed the high pressure pump. This is the fix for the vapor lock problems.

[Coachpete]

I have a 2005 Moomba LSV and have had the same problem since day one.
I think one of the issues is the entire engine compartment regardless of blowers running or not gets over heated and the fuel pump runs hot to start with. I live in Canada and we get a few days +30 C I.E. 86 F just a nice day on the water.
We normally run 8 hrs on a day like this but I can count on the engine failing after about 4 hrs. So first thing I found was put cold gas in and it runs fine. Next thing was pour cold water on the fuel pump it runs fine. Bingo Vapor lock. I did some measurements with my digital meter and discovered the returned fuel from the fuel tank was running around 38 C or 99 F. This seems a bit warm for gasoline considering the boiling point is 40 C. The fuel pump it's self at this point is too hot to touch and is measuring 55 C - 130 F. Thus the problem is we are putting Hot fuel back into the tank that we don't use as the fuel pump is the recalculating type. Now the compartment temperature combined with the return fuel temperature creates a heat cycle that keeps getting worse until the engine vapor locks or the gas tank explodes. What worries me is the flash point of gasoline is only 43 C - 109 F so how far are we from exploding in flames. So at this point I wrap a towel around the fuel pump and keep pouring cold water on it ever 15 min or so to keep the engine running. One thing I am going to try is to install a gas cooler using the lake water to cool the gas down before it gets to the fuel pump. This might help and I will keep you posted. To bad Moomba Supra can't figure this one out.

[xlvgg]

I just had this problem in Lake Powell last week. Luckily I found Bill and Tony's boat repair in Page and Bill knew exactly what to do. He said that between the fuel tank and the fuel pump there is a check valve or a ball in the fuel line. If this valve is to tight, meaning if the pump has to work to hard to pull the fuel past this point the fuel pump will overheat and cause vapor lock. I have an 07 XLV. He made this adjustment and we ran just fine for 2 1/2 days on Powell with no problems at all. No parts to fix it just a adjustment to this valve.

[xlvgg]

I posted this just this morning on the general chat. We went to Lake Powell this weekend. The first morning we went cruising to look for a spot to park the house boat. After cruising for 45 minutes and then returning to the dock the boat would not start. It would crank but not turn over. I called my dealer and he said it sounded like the fuel pump wasgoing bad and that it sounded like vapor lock. He told me to put ice or a cold rag on the fuel pump. I did this and it worked long enough to get us to the place we were going to put our house boat and then it would not start again. I started calling boat shops in Page to see if they had a fuel pump for my boat. None did but I luckily found the saving grace to our trip. Bill and Tony's boat repair shop. Bill listened to what was going on and told me it wasn't the fuel pump and that he could fix it in a couple of hours. I finally got it to start again with the cold rag trick and then got it to his shop at 6:30 PM. He said he would have it ready by 7:00 the next morning. I called him the next morning and he had it ready. The problem was a check valve of some sort between the fuel tank and the pump. The valve was making the pump work to hard to pull the fuel through the line and that was why the pump was overheating and vapor locking. $300 later and we finished the next two days without a problem. Many thanks to Bill at Bill and Tony's 24 hr boat repair shop in Page.

[Dave A]

I leave my blower on all the time we are running. If the boat has been run and we are going to eat lunch, or take an extended bread, I open my engine compartment with the blower on. I had this problem once, but since I have take those steps, I have not had it again. For some reason I never had this problem on my direct drive, only with the V-drive.




Dave

[zegm]

Thats because DD are better!!!

[Wake Master]

This is the answer from an older post by Engine Nut

A little clarification. The issue we have been seeing that is presumed to vapor lock is a condition that appears to be most prevalent on the 2007 model 340 engines with ETX CAT manifolds. The theory is that the extra heat generated by the catalysts allows the heat to build up in the bilge after the engine has been run for a period of time and then shut off. After it sits for a while a condition called "heat soak" raises the temperature in the bilge and allows the fuel in the line between the pump and tank to vaporize. The high pressure fuel pump will not pump vapor.

That being said, you can reduce the possibility of happening on any boat by doing a few simple things.

First, make sure your fuel filter is clean. As the fuel pump draws fuel from the tank through the filter, it creates a low pressure (vacuum) in the line. The harder the pump has to work the more vacuum is applied to the fuel. Fuel vaporzes at a lower temperature when it is exposed to a vacuum.

Make sure there are no restrictions in the fuel line between the tank and pump. The best condition is to have as straight and short of a line as possible. Each bend in the line can cause the pump to have to work harder and increase the vacuum.

After a hard run, try to let the engine run for a minute or two before shutting it off. This will help "normalize" the engine temperature and remove as much heat as possible from the engine. It might even help to disengage the shift control and raise the engine RPM in neutral to pump more water through the engine before shutting down.

Leave the bilge blower on after the engine is shut down to bring as much fresh air into the bilge as possible. Also, make sure the bilge vent hose isn't blocked, restricted or even disconnected from the vent and that the vent isn't blocked externally. It is not a bad idea on a hot day to lt the blower run all the time the engine is running .You'll also want to make sure to turn the blower on well before starting (if you shut it off) to make sure things are cooled off. This is not an unrealistic thing to do ... how many cars do you walk by on a hot day and hear the fan running after tha car has been shut off.

Your boat is significantly different than a car. The bilge of a boat typically does not have a lot of air circulating around it unless the blower is on. Also, cars have their fuel pumpslocated in the fuel tank.This keeps the pump cooler and allows the fuel between thepump and tank to be pressurized whichraises the vaporization temperature.

Try buying fuel from another source. We recommend using gasoline from a "Top Tier" supplier. Yuo can find which suppliers sell Top Tier fuel by checking out the following site. http://www.toptiergas.com/

I hope this gives you a little insight into vapor lock. It is a condition that has been around for a long time.It can be very frustrating but can be prevented in many cases by following a few simple procedures.
__________________
Larry Engelbert
Indmar Marine Engines
"Send Ed Down Under"