Engine full of gas....

[tkrfxr]

Friday check before the start of the week-end....

The smell of gas as I entered the cockpit made my heart sink....I turned the blower on, raised the engine hatch, and the bilge water has a layer of gas....there were drops of gas dripping down from the rear of the port exhaust manifold on the starboard engine....the gas was coming from around the PCV valve on the port valve cover....the port valve cover had gas coming from the oil cap...the fuel rail and pressure regulator were dry... the oil dipstick had oil all along its entire length...THE ENGINE WAS FULL OF GAS!

I closed all fuel lines off, opened the canvas covers, turned off the shore power, disconnected the bilge pump and called for help....

The mechanic came and hand pumped into two 6-gallon containers, a total of about 10 gallons of fuel...mixed with oil at the very end....

The last trip was Sunday before Memorial Day. The family took the boat, filled with fuel and made a run some 17 miles away. Outbound, the starboard engine had trouble starting at the gas dock, and required a little throttle to start. On the way, cruising at 25mph, settled at 34-3600 rpm, synched nicely...navigated and rafted up with some friends and powered down.

Returning home, the starboard engine again required throttle to start. Getting on plane, the engine had no trouble up to 3400 rpm, then would lose power, so that we synched and cruised at 3200 rpm, smooth. with no sounds...if I tried to increase power, the engines would fall out of synch and the starboard engine would surge and fall intermittently, so I backed off to the steady 3200. I made a mental note to have the fuel system checked and recalled seeing a VP parts bulletin recommending removal of a screen in the fuel pressure regulator, to be replaced by e-clips (which I had bought last year). The boat otherwise came off plane and slowed nicely with engines in synch, idled down and maneuvered uneventfully into my slip.

As a matter of routine, and knowing I would not use the boat for the next week, I powered down, dispatched the family, washed down, opened the engine hatch, both oil dipsticks and drive oil levels were good, then connected the water hose to each engine, and individually flushed with fresh water by running each engine for about 5 minutes, while I close the rest of the canvas. The starboard engine started on the first crank....wierd.

We are hauling out Monday....stay tuned.

 

[bruceb58]

i am assuming you have a mechanical fuel pump. Replace your fuel pump. Sounds like the diaphragm in it failed.

 

[Maclin]

You need to post what year and engine you have, I read it that yours is fuel injected since you mentioned fuel pressure regulator, but the more info the better.

For fuel injection to do that the injectors would need to be staying open with engine off and the fuel leaks into the cylinders thru open intake valvess, but then it has to get past the rings to get into the crankcase. The volume of fuel you are describing is a lot for it to be just residual pressure relief from the fuel system thru the injectors, just my opinion. Almost like the fuel pumps are staying on and the injectors staying open.

For mechanical pumps and carbed, I am still not sure how that much can get in after the engine is off, and you describe the engine oil level and condition as normal when you leave it. Anti-siphon valve in tanks should keep fuel from just running out of the tank into, well, anything.

 

[bruceb58]

I missed the fuel pressure regulator. Yes, you need to put your boat/engine in your signature or at least mention it in your original post.

 

[tkrfxr]

Sorry, I had the engine data on my signature but somehow it disappeared with all the forum maintenance updates....

Boat was hauled for outdrive service, and at the same time, get to the overdue maintenance items and fix the fuel leak problem....

The engines are 5.7 OSXi-DF, bought in 2004. 11 seasons of trouble-free boating, fresh water cooled, flushed with fresh water after each use, winterized according to VP Engine storage instructions, never leaked oil, never burned oil, always started on the first turn of the key...until now...


So the engine was cleaned out, several oil changes done, new starter, new heat ex-changer,manifolds and risers (were due), the fuel pumps in the fuel cell were tested, pressure regulator changed (screen had metal shavings in it, likely from the pumps?), the fuel system pressure tested, and held pressure appropriate for the specs, the cylinders were pressure tested, all ok... the fuel lines do feed by gravity, which they should not do. The injectors were taken for bench testing and two had to be replaced....but the techs say there is no way to leak 10 gallons in 4 and 1/2 days through the little passages of injectors, even if they were all open...

He suggested that perhaps, a fuel regulator hose, with 1/8" int.diameter, feeding the vacuum intake manifold, from a malfunctioning regulator, that receives fuel through the fuel cells by a gravity feed due to malfunctioning anti-siphon mechanism....

(this is a lot of theory and a lot of things going wrong at the same time...in a 10-year old engine with no prior problems until now...)

This means the anti-siphon valve on the tanks are not functioning....I own the boat since new, and never tinkered with the fuel tanks....

I do not know if there are anti-siphon valves on the tanks, but I know that USCG and ABYC require them in gasoline engine-powered boats.

I also do not know what type they are or should be, if ball-spring in a fitting, or a solenoid shut-off valve...

Either way I will monkey-down the the appropriate size and get access to the tanks today....

In the meantime, the mechanic will splash the boat and a we go for a test drive today...engine was tested and tuned on land....

Until the anti-siphon issue is resolved, the fuel lines will need to be shut off manually after each engine shutdown...