Fuel in Oil - Electric Fuel Pump

[smp]

Hi All. There is fuel in my oil and I'm running the facet pump so it's not the more common problem that the mechanical fuel pump guys are experiencing with the leaking diaphragm. I bought the boat in the winter when it was on the hard so I don't know how long this has been a problem. One of the things I did early on was 2 oil changes in a row, actually, right when the boat was splashed. Since then there can't be more than 12 hours on the engine (only use it to motor in and out) and the oil is thin, high on the dipstick and reeking of gasoline. I'm changing the oil today because I've read other threads on here that point to this being a very dangerous condition .... What would cause it to ignite (point of curiosity)?

Any troubleshooting steps you folks can provide would be much appreciated.
Thanks

[Dave Neptune]

Not likely unless~~~

smp, unless you have the facet running through the mechanical pump there aren't many ways for fuel to get into the crankcase. Has the mechanical pump been removed and replaced with a cover? I have seen instalations done wrong by routing through the mechanical pump, give it a good look and get back. If your unsure shoot a pic to post.

Fumes can be ignited in the crankcase via "blow-by" rare but sometimes cause catastrophic results.

Dave Neptune

[romantic comedy]

I am thinking that you could have the plug wires routed wrong, so that a cylinder or two is not firing. The fuel is not being burned and blowing past the rings?

[smp]

It's possible. I did have the spark plug wires off a few times to change/check the plugs. I'll check the plugs to see what they look like.

[Ball Racing]

I had a problem with the float in the carb once, and it was dumping fuel like crazy in the motor, and with the little scavange tube hooked to the intake, fuel that was puddling in the carb throat was being introduced into the intake track, and I beleive going past the rings into the oil.

[smp]

I had a problem with the float in the carb once, and it was dumping fuel like crazy in the motor, and with the little scavange tube hooked to the intake, fuel that was puddling in the carb throat was being introduced into the intake track, and I beleive going past the rings into the oil.

If you are getting gasoline into the crankcase via blowby wouldn't that be happening regardless? Fuel is being introduced into the intake manifold under normal operating isn't it?

I haven't pulled the plugs yet, though I should have yesterday I had the opportunity. I did look at the way the wires are oriented and they look to be in the right order, 1,2,4,3.

Question: if I wasn't running on all cylinders, would I be able to tell? Would the engine be running rough? It's smooth as butter.

[Kelly]

Question: if I wasn't running on all cylinders, would I be able to tell? Would the engine be running rough? It's smooth as butter.

The answer to this one is "yes". An easy test to see what this is like is to actually remove one of the spark plug wires when you are running the engine. You'll hear the difference (if the plug was firing in the first place). The A4 will run regardless but you can hear the complaining.

[smp]

Thanks for the quick reply. I'm going to assume I'm running on all cylinders.

So far I can only see two ways for gasoline to get into the crankcase:

1: mechanical fuel pump. This is not my issue. I have a late model engine, 1980 I believe, with an electric fuel pump which, based on things I've read, I believe to be a factory install. There is no (and I think never was) mechanical fuel pump.

2: blowby. When compression was tested by a mechanic back in the fall when I was buying this boat, compression read: 100/100/100/75. (but my memory is lousy so maybe it was 90/90/90/75. Three cylinders were in good order in any case) The 4th cylinder was low. He figured it was likely a stuck valve. I have not done anything to remedy this to date. I'm clearly new to engine mechanics but I don't see how a stuck intake or exhaust valve could cause this. But I could be wrong! IF it's the rings in #4 that are worn out, this could cause the blowby? There is certainly a little "puffing" out of the oil fill when the engine is running (with the cap off). But I expect this from any motor?? I should note that when the compression test was done he tested it both dry and with some oil in the cylinder and the results were the same both ways, hence the stuck valve diagnosis.

Any other way?

In the meantime, I should probably do another compression test (have to get my tester back from a friend first!) and maybe drop some marvel mystery oil into the cylinder??? I'm new to MMO as well.

Thanks all.

[hanleyclifford]

Check the pcv valve for correct operation. Another distant possibility is unburned fuel getting past the valve guides.

[sastanley]

Steve, I use a little oil squirter to squirt some MMO into the cylinders via the plug holes. My motor has had a couple of "crank too long, water backed up into #4" (at least) episodes and it has a periodically sticky valve..running it more helps, and I also put about 1 oz. of MMO per gallon of fuel in the fuel tank. It tends to stick when cold and get better after running it a bit.

Your compression numbers sound fine..I cannot provide any guidance on the fuel in the crankcase with an electric pump though!