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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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When I take the vacuum hose off the fuel pressure regulator while running, the pressure jumps up from about 50 lbs to 59 lbs, which I believe is about normal pressure
Sounds like the fuel pump is allowing the pressure it creates to be lost by not having a working back flow prevention in the system. Not sure if all pumps have a preventer built in to them but you probably will need a new pump at a minimum if you can find one or a whole new fuel pump module.
When the key is turned on the fuel pump should pressurize the line to the pressure needed by the vehicle and that pressure should hold. It should not go down after the pump shut off.
Thanks John, please don’t tell me I might need a new fuel pump after all, LoL. I’m afraid I might at about $200 or so plus pulling the tank and all that. Why would the pressure go up to normal with the vacuum hose removed from the pressure regulator? And it seems to start better with it off as well. Could I drive it with the vacuum hose off for short distances??
I looked for specs on what your specs for the pressure should be and can’t find any, but if it doesn’t hold the pressure when the key is shut off I do think if the pump is what controls the system and prevents pressure from being lost then you need a new one. You may be able to find just the motor like I did for my Dodge Neon, on eBay for $20 with a lifetime guarantee (of course I don’t own the vehicle any more so there is no guarantee any more for me). The whole module would have run anywhere from $100 – $225
If you are smelling gas then a small leak would let the pressure drop too. Have you checked for rusted gas lines?
No I haven’t checked for rusted lines. All this only started a month or so ago, until then ran fine although it did have idle surge from 500 rpm to 1,500 rpm but the car was doing that for a few years at least. I bought the car from my Mom a couple years ago and she had it 4 or 5 years and bought it used. Changing the fuel filter actually cured the idle surge but since the day I replaced it, I have smelled the gas smell. Gas mileage seemed fine for a few days then seems to be about 1/3 to 1/2 the mileage I was getting before. There are no leaks at the filter. What is the best procedure to check the lines If i decided to do that? I have not identified any gas leak under the car to this point. (As I posted before, after replacing the fuel filter, the car began overheating and I replaced the thermostat. Doesn’t overheat but seems to go from cold to half-way on the dash gauge after about 5 miles of driving which seems too fast to me. But of course now the stalling during driving is my biggest concern. Would an air flow sensor affect my engine the way I explained? It obviously has been running very rich since I replaced the fuel filter due to the smell and sometimes hard starting. Thanks for your help.
Hello,
I’m not exactly familiar with your GrandAm fuel setup-but your comments cause me to ask some potentially silly questions. First, is it possible to install the fuel filter backwards? Perhaps you did (or not). Second, do you by any chance still have the old fuel filter to attempt to go back to where you started? Third, did you possibly receive a defective or incorrect fuel filter? I agree with the comment about full fuel pressure key on engine off. Do you hear the fuel pump spool up when you turn the key on (no start)?
Just some thoughts…..The filter is on correctly. It has a connector on one end and a bolt on fitting on the other. The new filter is correct for my car. I never heard the fuel pump kick on before I replaced the filter which is why I first suspected the pump but it started on spraying starter fluid into the throttle body (and the relay was clicking when turning the key) and ran so I tried replacing the filter first. I’m leaning towards the fuel pump buy I guess I’m trying to talk myself out of that, lol, since it’s an expensive and time consuming procedure I will do myself. Thanks for the input!
OK, so much for my thoughts! Curious though, if no fuel pump operation then how did vehicle sustain running after it used up the starting fluid you sprayed to get it to go? Based on one of the ETCG videos a clicking relay isn’t always a conducting relay! The load contacts could be burned beyond conduction. I can’t remember which video he covered that in. Would like to know where the fuel odor is suddenly coming from after the filter replacement. Keep us posted and good luck.
Try crimping the return line with vice grips on a rubber part
of the line. See if the key on engine off pressure gets better.
if it does then fuel pressure reg is suspect and should be changed.Collegeman, I’ve heard about doing that but for some reason I can’t find the return line. Would it be around the regulator?
I posted this then it seemed to disappear so I’ll post it again. Couldn’t find where the metal gas line become rubber, probably have get under the car to find it but I don’t have a floor jack with me right now. An interesting development; today after cycling the key 4 or 5 times, the pressure shot up to about 59 or 60 (engine not running) but it won’t hold that pressure and slowly drops on the gauge to about 20 or so.
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