Boat Flooding?

I have a 2007 Moomba with the 340hp EFI engine. Last weekend and again this weekend after riding around with no problems and stopping to float the boat after restarting would sputter and die and would not restart. When this happens you can smell gas and I assume that the boat is flooded. Only way to fix problem is to wait about 30min to an hour and boat would start up fine and ran great. It has happened twice in the last two weeks and only happened twice in the two previous years. What is the cause of this problem? Could it be bad gas? Rocking of boat while swimming sloshing gas around? It is very embarrassing when this happens, look for suggestions.

Sounds like the fuel pump may be staying on when you are turning the ignition off...

My 2 cents...

Sounds like vapor lock in an EFI. Search on this forum or the skiers choice owners forum for vapor lock problems.

Vapor lock. George is right. Check for something blocking the engine vents. Look for a hot line next to the fuel line or pump.
In the short term, leave the blower on.

Years ago I had a vapor lock problem on an MC 205 with the Indmar 350 TBI. MC swore there was no way for an EFI engine to vapor lock. But the guys at SkiDim had a fuel line insulation kit that ended up solving the problem. I think it cost like $13 & was a breeze to install.

Same thing happend to my 06 Moomba LSV. I replaced the fuel filter and problem solved. Call your dealer, and ask for the Napa part number for the fuel filter. I think it was $8.00, and easy to replace.

I don't know the year and engine configuration but there have been a few efi engines with significant vapor lock issues. One was the big block in 2007, and a friends 08 Malibu with the 340 hp had problems that required rerouting the fuel lines from the filter to the injector manifold.

I had The same problem in a 06 supra, same motor, and it was bad gas.

I had the same problem on my 2006 Supra 21V - 340 EFI. For me it was vapor lock - only happened when it was hot. The dealer (under warranty) added a second fuel pump. I've never had the problem since.

As stated in other posts it's a know problem with the 340 EFI engines.

Fuel containing 10% ethanol is called E10. If you have ethanol in your gas, you run the risk of creating vapor lock because of excess vapors.

Ethanol “boils” at 87ºF (at normal atmospheric pressure) and turns from a liquid to a gaseous state. By comparison, most automobiles have their fuel pump in the gas tank, so the whole system remains under pressure unlike boats whose fuel tanks are vented. In a closed system, the higher pressure raises the flash point of the ethanol reducing the amount of vapor that is produced. In addition, most automobile fuel lines are outside of the vehicle allowing them to stay cooler.

Since most boat fuel lines are in the enclosed space (sometimes even insulated) of the engine compartment, normal ventilation will not cool the fuel significantly enough to avoid the potential problems of vapor lock. Furthermore, since the fuel pump in a boat is mounted on the engine (versus a car where the pump resides in the tank) the action of the pump can reduce pressure in the tank to below atmospheric pressure and further reduce the flash point.

Vapor lock on my boat. Running the blower stopped it or I can crack the engine cover. Do a search. One person solved their problem by zip tying a popcicle stick to the fuel line. Apparently there is a hot spot.

Same thing happened to me. I found that if you remove the intake manifold (6 or 8 bolts on top), then reinstall, it'll start right up.

My 325 Indmar did this a few times in the past couple of years. Dealer said probably vapor lock... ethanol related. Changed fuel filter but still used same gas last year and only happened once when I left it shut off for a while. Had to take a little ice from the cooler and cool the fuel line/filter and the intake and it was fine. This year my gas supply has no ethanol. I hope this will not be an issue this year.

I have a vapor lock issue on my 05 supra 21v. There was a thread about the issue on here a while back. It stranded me three times last weekend(for a short period of time). They say if you pour cold water over the water pump, it should start right up. Or you could add the additional pump mentioned above.
I don't know if it was a fluke or not, but the last time it happened to me, I turned the key on so it would start the fuel pump, I then pushed the button on the throttle and floored it, brought it back to neutral and started it. It ran fine. This was after sitting for about ten minutes, so like I said, it may have just worked itself out by then.

I had a similar problem.

It was a loose electrical connection to the fuel pump.

Relating to E10, how can you tell if your station is using E10? I'm not from the corn belt where everything seemed to have some grain based fuel, but some stations post 'May contain up to 10% Alcohol", others do not post anything, and have only found 1 (Sinclair) that posted that they do not use any Alcohol. Is this brand specific?

Interesting that this problem is being blamed on ethanol. When I had the problem, ethanol was not even available. And now that I'm running E10 everyday, the boat never has the problem (hope I didn't just jinx myself).

The pouring cool water over the fuel pump sounds like a similar fix to adding insulation around the fuel lines...... protecting the fuel system from excessive heat soak.

Since E10 is here for a while in most areas, I think I'd give that a try if I were having the problem. Wrap the fuel pump & fuel lines in some sort of insulation like Skidim.com sells.