Volvo 940 fuel system issues

[jana519]

Hey guys, so I have a 91 Volvo 940 Turbo that currently doesn't start. One week earlier, it started but had issues: bogged down at 2K RPM, wouldn't start warm, had to prime it multiple times, stalling out at cold idle.

Reading about this car, I learned it has two fuel pumps. First I believed the problem was the in-tank low pressure fuel pump, aka the pre-pump. I replaced that with a cheap $40 Delphi pump from AutoZone. Now it currently doesn't start at all.

I'm thinking that either the fuel pressure regulator on the rail on the main fuel pump is bad. The old in-tank pump was Bosch and it weighed about 8 oz more than the Delphi. I believe that the Delphi delivers less fuel pressure than the Bosch, so whatever part was having problems before doesn't work at all now with the cheap Delphi.

I've checked the fuel delivery and fuel comes to the rail when I prime the pump. The return fuel line at the pressure regulator was dry when I checked it. Also, when I spray starter fluid into the intake manifold it runs for a couple of seconds.

I'm wondering if the pressure regulator or the main pump might be bad. Is there any way to pinpoint the problem?

 

[NutBucket]

To check the regulator you'd need a fuel pressure gauge. That's the only way to do it without throwing parts at it.

 

[jana519]

To check the regulator you'd need a fuel pressure gauge. That's the only way to do it without throwing parts at it.

Cool, thanks. After I read my post I realized how stupid it sounded to put in the cheap in-tank pump rather than spending an extra $20 to get the OEM replacement. So I pulled the in-tank pump again, going to put the OEM replacement in tomorrow just to be absolutely sure.

Only problem is I dropped the cheap sending unit gasket in the tank. I don't know if there's any chance of fishing that out... :hmm: