Quote:
Originally Posted by Diseasel300
Was the Whoosh you got from the fuel tank positive or negative pressure? IE are you 100% sure it sucked air IN? It's not uncommon for them to blow air OUT. There is a vent with a bell shaped valve under the car near the differential that controls pressure in the tank. It will maintain ~1PSI of positive pressure in the tank, but should maintain 0 vacuum. If you have a vacuum in the tank, you likely have a blocked vent line or a failed valve.
There are no electronics or electric components in the fuel delivery system of the OM603 engine. It is 100% purely mechanical. If you bled the system dry, push the pedal to the floor (and hold it there) and crank in 15-20 second bursts with 2-3 minute rests. After 2-3 crank bursts, it should fire up and run. It'll do this on a completely dry fuel system too (empty filters, empty rack, empty lines).
If you did in fact pull a vacuum on the tank, your lift pump is in healthy condition, otherwise it would have stalled out long before pulling a vacuum. They're far more reliable and long lasting than people make them out to be.
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I'm pretty sure it was negative pressure. It's a good question, I had to play it back in my head. Pretty sure I recall that I had to pull gently to get it off, then heard the whoosh. There was no pushing outward sensation, pretty sure.
Re the no electronics, I'll be damned. Like I said, I really don't know that much about it yet, THAT was something you'd think I would have known. So does the lift pump do it all? Create residual pressure in the injection pump I mean? Looking at it I can imagine that the injection pump has its own power take-off somewhere in there.
This is actually very good news for me. My last 14 or so years have seen two BMW E30s as daily drivers. I took the first one from 214K to 440K (still running), the second only got about 50K on it before I was rearended hard. Anyway, nice cars but one PITA is two electric fuel pumps, one in the tank and on inline, one the underside in front of the left rear wheel. Both of them spendy in OEM (around $300 ea) and when the intank pump goes, not long before the inline will and it starts to whine loudly for a while. Twice I was stranded with dead inline pumps, the second time years after the first. I was prepared and swapped in a spare on the side of the highway up in Oregon. Not the most pleasant job with gas everywhere. I found aftermarket units that will work well enough, but the dreaded pump whine is always around the corner.