My '89 740 has 236K miles and has been a great car; however, I have run into a problem that doesn't make sense to me. A couple of weeks ago, the car was idling in the driveway and died. Since then, I have tried to restart several times - it will run for 15 seconds or so then die again. As we also have a running '91 940 that has the same relays, I traded the fuel pump and radio suppression relays out to see what would happen. It didn't help. Also, when I jumped contacts 30 and 87a on the fuel pump relay socket, the main pump on the 740 runs, although I could not hear the in-tank pump at all.

Trying to determine what was happening, I removed the cover from the fuel pump relay. There were two sets of contacts inside. The set that was to the top of the relay (in installed position) closed when the key was turned on. The lower set didn't seem to close at all. However, if I manually closed the second set of contacts, the car started and ran normally – at least until I let them open again.

It seems like I have two different problems. First, the in-tank pump seems to be dead. Second, the main pump doesn’t seem to be running when it should. Since installing a known good fuel pump and radio suppression relay didn’t fix the problem, is the lack of an in-tank fuel pump causing the problem? Could all of this be related to a bad fuel pressure regulator? I’m running out of ideas and don't want to start randomly replacing parts.

Thanks for any help you all can provide.

Chris