PS: On the “Original technical questions, answers, observations†page, I posted a thread called “Oil filler tube upchucking oil into my oil bath air filter.â€
Question for possible discussion: Could the unvented gas cap have caused all those problems? I had replaced the old vented cap with the non-vented cap at the same time I bought the first “new†fuel pump. It could be just a coincidence, but who knows?
I can't wait to see what the "experts and experienced" respond to that. Great question.
Well, I'm no expert but, my .02 is barely worth that, so.......
I believe the end result of m2j's upchuck problem was a bad pump (most probably a ruptured diaphragm) dumping fuel into the oil pan causing the oil/gas mixture to fill up and squirt out the filler tube. At least when replaced, it stopped doing that.
I'm going to guess that with a non-vented cap, there would be a vacuum (difficult to draw fuel forward) until the cap was removed to equalize. But if left to sit in warmer temps, that would allow the fumes to expand causing more pressure to "push" gas forward (possible flooding) until the the cap was removed to equalize. I don't know how much extra pressure an old diaphragm could handle, but if weak, I suppose it could be possible to get the leak started.
I don't know enough to say impossible.
