A Slightly Different "930 won't start" problem
 

Sorry for yet another one of these, but not sure my issue is covered by previous posts. Here's my story-

'77 930 3.0 with 23k original miles, I've owned for 19 years. Had some work done a while back that included R&R of engine unit. Hoped to clear up some oil leaks, but that problem was not adequately addressed, which prompted me to install a Rothsport inlet check valve in the oil return line, which helped. Shift issues prompted replacing the bushings and the shift coupler with a Stomski unit, which really made a difference. However, the difficulty returned, so I checked the motor mounts, one of which was so loose it was barely hanging on, and I suspect caused the engine to move much more than it should under acceleration. Both mounts seem Ok, so I just re-tightened them.

Long story short, the movement caused the oil return line (that I had installed) to come loose where it attaches to the engine, or at least that's what I prefer to think happened. Luckily, I had just backed it out of the garage and was out of the idling car closing my garage door when it happened, and the engine promptly shut off. I re-attached the line and topped off the oil, but the car won't start. I tried swapping out the fuel relays and checked both fuses, the original and the extra one the shop installed to stop the issues related to having only one older style fuse for two pumps. When my wife comes home, I plan to check the spark at the plug, since I can't do it alone. Normally, when I turn the key, you can hear the fuel pumps humming, especially since they're both the originals as far as I know. But all is silent, including the area under the hood. I think I can smell a faint wisp of gasoline from the rear of the car after trying to start it.

I guess my question is this; how coincidental could it be that the problem with non- starting isn't related to the drop in crankcase pressure? Do I follow all of the great advice on the 930 threads to chase electrical of fuel issues? Or did the engine quitting because of the line letting go cause some other issue not related to those more common in a car that hasn't been subjected to losing a quart or so of oil and turning itself off because of the drop in pressure? I'm getting up in years and finding it harder and harder to contort myself into position to get to where and what I need to find an answer!

I would appreciate any advice from the people on this great board, as I can see there is much more knowledge here than I have.

Thank you.

I’m afraid there’s no relationship between your oil line coming off and the car shutting itself off. There is no low oil pressure cutoff switch.
If your engine was actually hanging low on the rear mount, you might have tugged your main harness connector loose at the drivers rearmost corner.
Check the 930 turbocharging FSU forum and read the sticky up top

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/547032-sticky-common-answers-why-my-car-doesnt-start.html

Remember, an engine needs both fuel and spark to start. A simple 5 minute test is comprised of a fuel test (carb cleaner into the air filter),
and a spark test (coil wire removed from distributor & placed ~10mm from engine metal) while the engine is cranking, each done separately.