Boat dying after long idles

[Onelovedex]

I decided to create a new thread because my old one was called knock sensors which now I know has nothing to do with my issue. After more drives on the water here is what is happening.
-Boat will crank fine cold and idle out of long cove no problem.
-Boat runs great as long as no idles.
-After running for longer than 20 minutes it will only idle for 5-10mins before it bogs down and dies.
-If I wait 15mins the boat will start and run again fine.

I thoroughly cleaned the throttle body butterfly valve. Any suggestions on where to start next? My nephew thinks the engine is flooding because of the strong fuel smell when the issue happens.


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[Onelovedex]

Yes sorry. 2008 tige Z1. 5.7L vortec 350


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[lexpression]

I have exact same symptoms on a 2003 5.7L Vortec Marine power. My next step is to change the fuel pumps. The g-force pump is back-ordered so that is going to take some time, the electronic low pressure pump should be in my hands in a couple of days. I'll let you know how it goes.

[Onelovedex]

I should have put what new things are on the engine. High pressure and low pressure fuel pump, ICM, coil, plugs, wires, cap, fuel filter. So my problem shouldn’t be any of those in theory.


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[lexpression]

Dang your ahead of me then. changed the coil, cap, plugs, and temp sensors.

[AJMichael]

Try some SeaFoam and clean that throttle body out, you might have a bunch of gunk built up and the Orifices are clogged up. If that don’t work run through full tune.

[Onelovedex]

[mention]AJMichael [/mention] I have already run two big bottles of sea foam through. That is my go to. I’m not sure what you mean by full tune?


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[SONIC]

Sounds like it may be vapor locking?
If the engine compartment gets too hot the fuel can boil and cause what you're seeing.
Try running it with the hatch open and see if the symptoms persist.

[rcarr]

My guess is water in the high pressure fuel pump.

Before you check this, order a new high pressure filter and O-ring (Michigan Motorz is my source). The rubber O-ring expands when it seals the fuel filter canister once it comes into contact with fuel. You will not be able to re-use the O-ring.

I always keep a fuel filter on my boat just in case.

PS removing the high pressure fuel canister can be a bitch the first time you remove it.

[USWaker]

Ooohhh… is that the engine that has the tiny plastic fuel lines that run through the inside of the intake plenum?
I think it was called CSFI or something like that. Maybe MPFI. In any case, sometimes the lines leak and case a rich condition. They used it in early vortex’s. Not t sure if they had them in marine applications though.

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