AUX Fuel Pump

[BIGALF]

I have a 1997 SeaRay Deck Boat with a Merc Cruiser 5.7 throttle body EFI. For the last 2 years I have been having a problem with the fuel. The boat is on a trailer so I use regular car gas and fill up the boat before I launch it. It's so hot down here in Florida that unless I open the boat engine cover about 1/2 hour before I dock it will get a vapor lock in the EFI pump and I will not be able to start it for about 2 hours after it cools down. The only fix I have so far from the dealer is to put an additional pump in line with the EFI pump. It sounds like a good idea but $600 plus is a lot of money to spend and hope it will work. If it will work then I will do the job and make my wife happy. I thought that if I switched to marine fuel with zero ethinol it would fix the problem but start another.
Any other ideas would be helpful.

 

[Islndstyle1970]

Re: AUX Fuel Pump

this is a little trick that might help. When I was in Iraq our equipment encountered the same problems. What we did was poured water directly on the fuel pump and fuel lines. After doing so we could start our engines right up. Try installing some sort of fan to circulate cooler air in the engine compartment so it'll bring the temperature down in the engine compartment.

 

[BIGALF]

Re: AUX Fuel Pump

Glad you came back ok.
I also heard of people putting a bag of ice in the engine well. The service notice I found from Merc said to turn blower on and let set at idle speed for 5 minutes before turning engine off. As I remember that did the jub when I did that. I just forgot about doing that.

 

[BIGALF]

Re: AUX Fuel Pump

My latest idea to cool the air around the engine before a heat sink gets into the fuel line is to wrap thermoshield tape around the fuel lines from the tank to the engine, as much as I can get to. The vendor for this tape is Thermotec that supplies this material that looks like silver metal tape. This tape is used on high proformance race cars. They say it is also used as a shield to the fuel lines to protect radiant heat to get to the lines and cause the vapor lock.
I will also open the 6" hole in the side of the enclosure that is used to put in a fire protection tank instead of opening up the hatch if a fire is in the engine well .
Also I will add a new 4" line to the area that was a glass holder that is never used. I'm also thinking of adding another fan to take in outside air to the engine well. This will give me 2 fans. 1 going in and the other blowing out hot air.
Since most of my boating is at slow or idle speed I need to get more flow of outside air into the engine hood. Even though summer temperature is usually in the high 90's here in Florida during the summer season it sure is a lot cooler then what is inside the engine compartment.
What do you think of this idea?

 

[jeffersondodson561]

Re: AUX Fuel Pump

That is the correct fix. I am not a big fan of putting any kind of water or what will soon become water anywhere near the fuel system or intake considering that in boating you are constantly surrounded by water. My question is have they done a check of the fuel system for restrictions. Restrictions could be muddobbers in the vent opening, clogged/hidden water seperator, clogged fuel pick up. And have they done a fuel vaccum test?
At our old shop we would have a autozone fuel pump approx. 4-8 psi fuel psi, put a vaccum gauge (sears) inline with about a foot of clear tubing attached and attach it to the fuel pick up and route it back to the gas tank and watch the gauge and inspect for air bubbles in the clear tubing, the gauge should not read more than 4" of mercury. Any more and that is a problem. Your shop should have something similar.

 

[BIGALF]

Re: AUX Fuel Pump

Fuel system has been checked out from the tank to the engine. The fuel pump was replaced just because they didn't know what was wrong when my engine would bog down after running for an hour. All they should have changed was the screen inside the fuel tank. I found that answer from iboats and it fixed my problem. Good job iboats! I will not be that stupid again and not ask them what they want to do before I give them a blank check.
Now they want to add a aux. fuel pump for the vapor lock. I know that will work but I found a cheaper fix. The engine box has next to nothing in ventalation so I took out a 4 inch access hole door and put a PVC elbow and 5 foot high pipe with another elbow where the access hole was. I tried it today and found my engine running cooler and no vabor lock when I stopped for one hour without opening the hatch. Cooling the inside of the hatch is the fix so I'm adding more cooling holes in the box as long as it doesn't increase the noise.