351M 10W-30/ 89 octane in the pan - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

jonnydesert · 02-08-2009, 13:14

got a 79 F150, drivin it last week, and it quit on me. pulled the stick out and found about a 40/60 gas/ oil mix when a few days before it was low a quart and very much straight oil. changed the oil and replaced the plugs (all 8 were oil fouled) tried everything to start it, ignition system, fuel system, timing, everything checks out but still no combustion. did a cranking vacuum test and got a fluctuation of 2-3 inches. thinkin it's either in manifold gasket, rings or valves. any ideas so i can no what to rip apart?

kdtrucker · 02-08-2009, 22:42

Not sure if I can answer this one but I would start at the fuel pump, it probably failed and backed up into the crankcase.??? Don't know...just a place to start.

**jwko** · 02-09-2009, 10:16

Quote:

Originally Posted by kdtrucker

Not sure if I can answer this one but I would start at the fuel pump, it probably failed and backed up into the crankcase.??? Don't know...just a place to start.

Yep, sounds like he has more dumping in the oil pan than going to the carb.

jonnydesert · 02-09-2009, 12:32

tested the fuel pump, it's an aftermarket electric (the cam lobe for the mechanical is too worn to pump) got maybe 1 PSI. So that's the cause of the truck not running, so i must have somethin else goin on that fuel is gettin in the oil???

**jwko** · 02-09-2009, 13:13

So the old pump is totally bypassed?

kdtrucker · 02-09-2009, 13:27

Well if your using an electric fuel pump and the fuel is from the tank to the pump to the filter then to the carb, I can only think that your intake is leaking from underneath and spilling into the lifter valley and then into your oil. Could be why it won't run or have sufficient vacuum also.

If you have another intake try it first to make sure that is the problem, if not take the intake to a machine shop and they can test it for leaks.