Weird hard start question

[nikuso]

Hi everyone,

Okay, so I'm new to posting here, although I've taken advice from these forums many times now, so thanks in advance!

I have a 92 740 non-turbo wagon (regina). I've recently had a hard time starting the car. At first attempt car starts no problem, but when I shut it down then try to restart it cranks for 10-30 seconds before firing up. It has also stalled a few times when idling at the light or while decelerating. Starting has recently become even harder - to the point of serious difficulty (after initial start and shut off). Checked compression and got 130psi across all cylinders, although plugs were all fouled and black (so I'm thinking something to do with the fuel/air mix being too rich...?). But here's where it gets weird - after replacing the plugs I decided to try to start it up and couldn't at all. After a couple tries I noticed I couldn't hear the fuel pump at all when I turned the key to the on position. Monkeyed with the fuel pump relay - that looks fine inside. Switched out 25a fuel pump fuse - also okay. Then I happened to notice that in the "on" position I could hear sound coming from my speakers. I turned off the stereo (aftermarket), switched off the key and turned it back to the "on" position. Voila - fuel pump started, and car fired up immediately. Also started fine on several subsequent attempts, both with the radio on and off. I have read in several threads about the radio suppression relay being a culprit and have already looked for mine (to no avail), and am wondering if that is playing some part in this. Any thoughts would be greatly appreciated as I don't trust that this current success will last!

[Fred760DC]

Radio suppression relay has nothing to do with the radio. Them funny Swedes. It powers the Fuel Injectors. When mounted inside the cabin it fuzzed the radio signals so they moved it on the other side of the fire wall into the engine compartment.
Good luck

[nikuso]

Thanks for the reply - I know it has nothing to do with the radio, at least in theory, but I did find the coincidence peculiar. In either case, I replaced the RSR and the plugs were no longer fouled after a day, and car was running smoothly with no issues. Then it started stalling again. Now it simply cuts out while driving - every once in a while, but at any speed. It will restart, typically in just a few seconds after the stall. Also, service engine light is now on for the first couple minutes after starting the car, then turns off. Checked ecu self-diagnosis codes and got idle valve signal and low voltage. Any thoughts?