Volvo: 87 740 turbo wagon, fuel pump relay, jeff barnes

Question
Hey Jason,

I'm really hoping you can help me out, right now my car is sitting in a Uni-Mart parking lot in the middle of nowhere.

If a may run you through the chain of events and trouble shooting I've done it might give you a clear picture.

I was tooling down a hill and the engine sputtered a few times then died.( the sputtring i'm not sure about, I kind of felt it more than I heard it. I managed to coast into a parking lot.  First thing I did was check and see if I was getting fuel.  I pulled off the fuel line and foud I was not getting any flow.  So I checked the fuel pump fuse and It was OK.  So I got out my multimeter and checked the fuel pump relay.  And I noticed that the pin that should go positive when I turn on the ignition wasn't going positive.  So I jumpered 12V to the pin to see if I could get the pump going.  I did and I managed to spray fuel all over because i forgot to reattach the fuel line. So I thought "ok" I can jumper across the relay contacts and get the car home.  Well it still wouldn't start so now I thought something funky is happening with the relay,  better just replace it.  So I got my brother to pick one up and bring it to me.  I replaced the relay.  And the problem still exists.  The pin that should go 12V high for the pump doesn't respond.  And what also troubles me is that if I jumper the fuel pump to get it running Shouldn't the car fire up?  It just turns over.  Is ther something that controls the ignition as well as the fuel pump?  Please help.

Sincerely Jeff Barnes

Answer
It sounds like you might have had 2 problems, or maybe one, and your relay was working fine.  If you jumpered the relay, and confirmed the pump was spitting out fuel, while the engine was cranking, but the car still was not starting (hope I got that right), then I would turn to electrical issues.  Technically, when the car cranks, it should provide itself with spark, you don't really need any other components.  With that said, I suggest going through the distributor - coil - spark plug check to make sure everything is in order.  Hold a spark plug (unscrewed) close to the chasis while cranking to check for a spark arc to the car.

If after all the checking, you've discovered spark is coming to the plugs, and fuel is getting through the injectors (check to make sure there aren't any clogs in them), then I would turn to the knock sensor.  If that fails, no matter how much spark or fuel the engine gets, the computer can time the ignition and it will never start.  Let me know how it goes.