www.iFourWinns.com

I have 1996 Four Winns Volto Penta 3.0L GS motor. Engine name: OMC Cobra. Mod# 302cpnca, ser# t01288344. My boat ones in the while, especially when temperatures outside above 95F ...would just shut it off when running at 3200-3500 rpm for like 30-45 minutes. It does starts right back up.... and then again.... run for 30mins...out again. Never shuts it off during a cooler seasons. I have put in: New thermostat, New thermostat sensor(runs at 130F), New Distributor with New ignition module, New wires, New Coil, New Sparkplugs, New kill switch(just in-case). Check all connection.. seams to be in good shape. What can be wrong????? I notice that the fuel line(plastic flex line, Not the main metal fuel supply line) that connects from the top fuel pump and runs to the back of the carburetor was almonds bend shut. Maybe just a little short line... that is why is almost shut close at the connection of the back of the carburetor.

THIS IS WHERE ORANGE LOOKING PLEX CONNECTS AT THE FUEL PUMP:


RUNS OVER THE MOTOR:


WHERE IT CONNECTS IN THE BACK OF THE CARB


HOW BEND WAS A LINE:


Can that do anything with a motor shutting off?
Any help/suggestion would be greatly appreciated! Thank you is advance!

Does it sputter and die, burp fart and die, or just simply shut down?

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2004 - 288 Vista
Twin - 5.0 Volvo Penta GXi DP

That hose, while it should fit better than that, has nothing to do with the engine sputtering. It is a safety hose, if the diaphragm on the fuel pump leaks, the fuel will get pumped through that line and go into the carb, instead of running out of the pump into the bilge (very dangerous).
What you describe can be vapor lock where the fuel in the carb gets so hot it starts to boil and then can't flow through the jets to keep the engine running. You may need to fit an insulator under the carb base to insulate it from the heat of the intake/exhaust manifolds. Sometimes wrapping the metal fuel lines with insulating tape like for water pipes also help them not get too hot. You may also need better air flow in your engine compartment to carry away some of the heat.

I'd also check the temps of your exhaust system. If the exhaust riser and manifold are getting clogged, or the raw water flow is weak, the exhaust can over heat (ie the manifold and riser can exceed 130-140*F which is a typical temp for these parts) and that heat getting transferred to the carb is what is causing your problem. Use an IR temp gun (can get it at Radio Shack) to measure temps of the exhaust manifold.....

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88 Four Winns 200 Horizon
4.3 OMC Cobra-4bbl
2002 Walker Bay 10/2012 Suzuki 2.5
2008 Walker Bay 8

1998 Jeep Grand Cherokee 4.0/Selectrac
2007 Jeep Grand Cherokee 5.7 Hemi/Quadradrive II

IR temp gun is cheaper at Harbor Freight... Just sayin'...

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2008 Four Winns h180 Bowrider
3.0 Volvo Penta

2013 Dodge Durango HEMI

It just shuts down in a split second. Like I would pull the key now or unplug the kill switch.

Thank you for a great information! I will wrap the fuel lines, insulate base of the carb and take temp of the exhaust/intake manifolds. Also will try to find a solution how to get more air flow in engine compartment.

Will do sir!!

It sounds like you are on the right track looking at the ignition system and electrical.

Have you chased the power and ground from the battery to the motor, and up the ignition switch at the helm?

When ever I hear an issue like this is dependant on Weather I always start wondering about grounding.

Good luck.

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2004 - 288 Vista
Twin - 5.0 Volvo Penta GXi DP

Not sure if you would agree, but I always place my hands on my manifolds to check temp. If you can't put your hand on it, or even if it feels really hot, it's too hot.

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2004 - 288 Vista
Twin - 5.0 Volvo Penta GXi DP