Gas in Exhaust and in Oil

[Erik]

Don,

Thanks for your response regarding the washer. Now I have another question that I hope you can help me with. I have seen two other posts for similar issues.

I have a 1979 Catalina 27 with an Atomic 4 gasoline engine. It has an engine mounted Facet Electric Fuel Pump. I have noticed that when I start the engine there is a sheen on the water coming from the exhaust. There is also some black crud on the surface of the water that stops after the initial start. The sheen is not speckles, but a continous "plume" on the surface. Not a huge amount, but definitely there. Since reading a thread on your site, I checked the oil. The oil has a gas smell and the oil level has gone up. It also looks/feels thin. I read that with a mechanical fuel pump the culprit is likely the diaphram. Does that mean that the electric fuel pump is the cause of my problem?

If so, I see that there are two fuel pumps on your web site. One 2-3 psi and one 4-5 psi. How can I tell what I need? I don't see anything on my pump that specifies a "psi". Are these fuel pumps wired the same way that an older pump was wired?

Any help would be appreciated. By the way, this is a great site!

[Don Moyer]

Erik,

I don't know of any way that gasoline can enter a crank case through an electric fuel pump.

From your report of the large amount of crud coming out with your exhaust, I get the notion that you may have a cylinder that is not firing for some reason. This condition would account for your observation of a small amount of unburned fuel leaving with the exhaust as well as a small amount of fuel getting past the piston and into the crankcase. The only uncertainty in this diagnosis is that the amount of unburned fuel that works past a non-firing cylinder is usually not enough to show up as an increase in the oil level.

In any case, I would measure the compression in each cylinder and check the condition of the plugs before performing any more serious maintenance. If the compression is good in each cylinder (90 psi or so), it may be the case that you simply need to tune up the ignition system.

You might also remove the flame arrestor and check the intake throat of the carburetor for raw fuel. If the float valve (or some other problem) is allowing too much fuel to pass into the float chamber, the engine could be running with a very rich mixture. A rich mixture in combination with a non-firing cylinder could account for the unusually large amount of fuel showing up in your crankcase.

It has been our experience that most mechanical problems end up having a single cause factor which in turn results in a series of events leading to the ultimate failure. A carburetor defect could be such a single "primary cause". The rich mixture would result in one of your plugs fouling, which would cause the non-firing cylinder, which would cause fuel to pass by the piston in that cylinder, etc., etc.

Regards,

Don Moyer