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gonofry
12-14-2012, 05:10 PM
I have a 1990 Prostar 190 and yesterday noticed that there was oil and fuel mixture on my dipstick. Is this a fuel pump problem? At slow speed there is a lot of dark smoke and it is hard to start.

thatsmrmastercraft
12-14-2012, 05:15 PM
There is something making your engine get too much fuel. Likely sources are blown power valve, stuck float or the secondary side of the carb is stuck open. I would start by carefully looking down the carb while it is running to see where the source of all the extra fuel is coming from.

Did your engine backfire through the carb recently? That could cause the power valve to fail.

petermegan
12-14-2012, 06:03 PM
Not at all familier with your engine, but is it running a mechanical pump on the side of the block?

thatsmrmastercraft
12-14-2012, 07:31 PM
That is a mechanical pump. If the pump fails, the diaphragm usually fails and there is fuel in the overflow tube which runs to the carb.........another possible source- just not as likely as a carb issue.

petermegan
12-15-2012, 02:02 AM
Ok, Just thought if a diaphragm had failed it would have been a large source of fuel directly into the oil. Have fun.

thatsmrmastercraft
12-15-2012, 02:09 AM
Ok, Just thought if a diaphragm had failed it would have been a large source of fuel directly into the oil. Have fun.

In theory it could, but with the engine running so rich as to be blowing dark smoke at slow speeds, it points to a carb issue. having fun is what it is all about. Cheers.

Jerseydave
12-15-2012, 10:14 AM
Power valves are know problems on holley carbs but they usually cause a bad "stumble" on acceleration. Sounds like you have a stuck/sunk float or high float level. With engine warmed up and at idle, look down into carb. If you see it dripping gas into the venturis then you need to rebuild or replace the carb.

thatsmrmastercraft
12-15-2012, 10:22 AM
There is always the possibility that some debris is not allowing the secondary throttle blade to close. Had this happen to me on the first days of a weeks vacation a couple years back. Popped off the secondary bowl, cleaned it out, put it back together and was good for the rest of the week. I do like blue reusable gaskets.

rjracin240
12-18-2012, 12:59 PM
Might be a wild guess.......if you rev the engine before shutting it down this will also in some instances cause fuel to get past rings and into oil sump

petermegan
01-28-2013, 05:33 AM
Gonofry how did you get on? solve your problem??