Low Fuel Pressure, gas smell, stalling

[Steve]

2001 Grand Am 3.4L

I had replaced the fuel filter a few weeks ago after no start condition. Ran but now poor gas mileage, gas smell and died on my 4 times yesterday at highway speed (first day it has actually stalled while running). Obtained a fuel pressure tester and it show 49-50 lbs pressure while car is running at idle. Fuel pressure shows 0 when cycling key only so the system is not pressurizing until it is started. Starting is also hard most times. I’m thinking the 49-50 lbs pressure is about 10 lbs too low while running?? I’m suspecting fuel pressure regulator but don’t see any fuel leakage from the vacuum hose. Any ideas??

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[Steve]

I just drove about 16 miles round trip to the store including going up and down about a 1,000 mountain with the vacuum hose off of the FPR and never stalled any. Didn’t smell any gas and gas mileage seemed about normal. Not sure what that means..

[Steve]

Haven’t had time to do much on my car in the last day or two. However, I drove it an additional 20 miles or so today WITH THE FPR VACUUM HOSE DISCONNECTED and it never stalled any and also no fuel smell. Although the RPM’s did fluctuate about 1,500 up and down a couple times while running speed (straight road, no hills). I could disconnect the return fuel line at the FPR since it’s metal and can’t crimp it but not sure what that would tell me. What has me stumped is the vacuum hose being off and it running and not stalling. I know now that is normal to have about a 10 lb increase in fuel pressure with the vacuum hose off the FPR so maybe that is giving me enough bump in pressure that it won’t stall even if the pump is weak (I assume)?? I have no gas whatsoever seeping from the FPR. I guess I’m still trying to rule everything else out before investing in a new fuel pump, although I know that might be the problem in the end. May clean the MAF tomorrow, don’t think that’s the problem but it likely needs cleaning anyway since it’s probably never been done (its got 163,000 mile on the car).

[college man]

With the vac line off the fpr. you are feeding more fuel
to the injectors which may be compensating for the fpr
bypassing to much fuel back to the tank. Thats why the
fpr return line crimp test. Is there a rubber line portion
back at the tank you could crimp?

[twiggy]

Maybe your pressure regulator is bad. I’ve heard of them leaking through the diaphragm too.

[Author]

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