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Fuel in the bilge...

fmrosell

New member
Yikes!

Last Sunday, on Memorial Day Weekend, the first outing of the season, we took the family to the gas dock, fueled up 75 gallons, both tanks full. The trip to Lloyd Harbor was about 1 hour, cruised 25 mph at 34-3600 rpm, with strong winds about....Had to throttle up the starboardr engine to get it started at the fuel dock, and also on the return trip. The return trip also showed some loss of power in starboard, and required backing off to 3200 rpm on plane, because of intermittent surging and falling off of the starboard engine when synchronizing (manual). Once at the dock, turned off engines, checked both and found normal oil and gear oil levels, connected the fresh water hose to each engine and individually flushed fresh water by running each engine for 5 minutes... all looked well... and closed up the boat until the next weekend... both engines started on the first turn of the key....Trip fuel consumption was 62 gallons (30 port, 32 stbd)...

Thursday I changed a spreader light, all looked good, the bilge pump emptied out some rain water from the previous few days, no smell of gas...

Friday afternoon, the smell of gas was noticed before entering the boat!...blowers on, shore power off, engine hatch up! Gas in the bilge!

Port engine all good.

Starboard engine...gas drip on rear of port exhaust manifold...
Throttle body, fuel rail, fuel regulator, intake manifold,,all dry...

oil dipstick...completely covered in oil to the very handle!

oil cap: open, look and fresh clear gasoline in the stbd valve cover, PCV valve disconnected, gas in the port valve cover!

THE STBD ENGINE IS FULL OF GAS~! Twin Volvo Penta 5.7 OSXi-DF

An emergency cleanup was done and about 10 gallons of gas were hand-pumped out of the engine, followed by removal of the plugs and cleanup of gushes of gas from several, but not all of the cylinders...

Hauling out today. There is no shortage of theories around the dock....What do you think?
 
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First place I'd check is the oil pressure SWITCH ( and relay if equipped) that is supposed to shut off your electric fuel pump under no oil pressure conditions...

Next the anti siphon valve on that engine's tank. Until fixed, shut off fuel valves when leaving boat... Generally a good idea anyway.
 
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First place I'd check is the oil pressure SWITCH ( and relay if equipped) that is supposed to shut off your electric fuel pump under no oil pressure conditions...

Next the anti siphon valve on that engine's tank. Until fixed, shut off fuel valves when leaving boat... Generally a good idea anyway.

The anti-siphon valve is almost certainly bad....I recall, in retrospect, that at winterizing, there was fuel coming out of the hose when I disconnected it from the fuel cell to connect an auxiliary tank with storage fuel mixture....I then quickly closed the fuel line .


the fuel pumps are OFF when the engine turns off... and the engine batteries are turned off when leaving the boat....whatever the low oil pressure switch does, the pumps are off when the key turns off the engine.

So, can the fuel, draining by gravity from a higher level, through a bad anti-siphon valve, pass through a fuel cell with low and high pressure pumps, into the fuel rail, and out a presumably bad injector, into the cylinder, around the piston rings, and over a period of four days, fill the oil pan and up....until the level of fuel reaches the other cylinders, and fills the valve covers...and leaks through the oil cap and into the bilge?

That is the question....
 
Has anyone heard of or seen this kind of fuel leak?

The injector experts don't think an injector, or even several injectors open at the same time, could dump 10 gallons in a period of 4 and one half days....

They suggested looking for a bad fuel pressure regulator, which could return fuel via a small hose to somewhere on the valve cover or vacuum system...

Any thoughts....appreciated...

The tank definitely drains by gravity....so the anti-siphon mechanism on the stbd tank is non-existent.
 
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