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 will ever have.

Thank you.

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

I would remove air filter and press the plunger ign on and if no fuel pump sound you got electrical problem.

you have to check for spark first.
if you have spark then look at fuel.

first I would check the fuse. it may not be making good contact.

the fuel system is a bit complex for most.
it has 3 relays and 2 switches
follow the link above for more detail.

if both pumps are not running I would try grounding the wire to the over boost relay first.
if that's no it then I would look at the overboost relay.

I agree that a quick test is to use a timing light or spare spark plug to confirm spark. If you have the standard 6-pin Bosch CDI you should hear it whine with ignition ON. If this car has an 8-pin box these do not whine.

Once you have confirmed spark spray starter fluid or brake cleaner into the intake to see if the lack of fuel (and introduction of starter fluid) makes it run briefly.