I think I'm getting fuel in my oil 89 mustang 5.0

John Bzstang

Dec 9, 2020
Just had a motor put in my 89 mustang stock 5.0. It had a 331 stroker in it with a bigger maf and a ecu with a chip it had a aftermarket holly systamax intake with 24lb injectors. So when they swap the motor to the stock 5.0 with the stock intake and stock 19lb injectors it still had the chipped ecu and bigger maf. It was popping and things when you give it gas and starting hard with the new motor. Now I checked my oil and it is way over full and I think it may have gas in it. Would this be from the bigger maf and chipped ecu trying to feed it to much fuel? So I put the stock maf and ecu in the car now and it runs great but havent ran it enough to see if gas is getting in oil still.
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wanna catch the space herp
10 Year Member
Sep 1, 2010
Kearney, NE
Oil is cheap compared to a rebuild.
Without a mechanical fuel pump, injectors (huge flow or a stuck one), or a supplemented nitrous system are the only likely ways it could get that much gas in the oil. And I suppose your fuel pressure regulator could have picked then to gush into the vac hose. Do also check that.