2005 5.0 GXI will not start when hot outside

Coach Greg

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Joined
Aug 20, 2013
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2
I have a 2005 Four Winns with a 5.0 GXI and about 150 total hours. I bought it with 75 hours last year and the boat has run great and up till now no problems at all. Recently I could not start the boat. It turned over and fired and ran for about 5 seconds, which is normal and I usually can start it after that and it runs fine the rest of the time in use, always starting and running on the first start. This time it would not fire after the initial 5 second run. It would turn over and almost "catch" but would not run. I tried this for a few hours, letting it sit 5 minutes to 30 minutes between starts. Thinking possible vapor lock, I opening the engine hatch after the initial engine start failure. I came back the next day, still hot outside (90 F) and it did the same thing. I came back again the next day and it was much cooler outside and it fired right up, first try. I brought it in for a check up and the mechanic did a basic tuneup saying it needed it but that vapor lock could be an issue since the hatch if very well insulated. I ran it about 5 hours over the next week or two with no problems. Now again, I came out on a hot day (85 F) and it fired up and ran for the 5 seconds, quit and then would not start, always sounding like it needed fuel. I opened the hatch and sat for 2 hours trying to start it every 20 minutes or so but it would not start. My boat has an insulated hatch, and then the boat cover also covers the engine compartment. There is no canopy shielding the boat from the sun. Is there a chance that it is getting so hot in the engine compartment that even opening the hatch for a few hours is not eliminating vapor lock? Any ideas?
 

Volphin

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Jun 5, 2011
Messages
1,405
Re: 2005 5.0 GXI will not start when hot outside

Sounds like water in the fuel or fuel starvation to me. Check your filters.
 

Coach Greg

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Joined
Aug 20, 2013
Messages
2
Re: 2005 5.0 GXI will not start when hot outside

I agree that I think it is fuel starvation due to vapor lock. If it were water in the fuel, wouldn't it be an issue when it is cooler outside also? The problem I am experiencing only occurs when it is very hot outside.
 

Volphin

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Jun 5, 2011
Messages
1,405
Re: 2005 5.0 GXI will not start when hot outside

I agree that I think it is fuel starvation due to vapor lock. If it were water in the fuel, wouldn't it be an issue when it is cooler outside also? The problem I am experiencing only occurs when it is very hot outside.

It may very well be vapor lock, but it's not super common. Work the problem from the simplest to the most difficult. Simplest is to replace water separation fuel filter. Then monitor fuel pressure if symptoms re-appear. You will have a high side and low side as your engine is fuel injected. You may also have a problem with the IAC valve. FI motors don't vapor lock easily as they use fuel rails to the injectors. There may also be an oil pressure switch or temp switch fault causing it to have a no-start. It's a protective measure built into the system. IF this gets over your head, let the dealer take a look.
 
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