Fuel Pressure

Tiny
ROWDEE
  • MEMBER
  • 2004 PONTIAC GRAND PRIX
  • 168,000 MILES
When you start the car, it idles perfect. You can rev it up it does good. Put it in gear and start to take off and the car will die. I checked the fuel pressure at 52/54 lbs. What else could be the problem?
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Sunday, September 1st, 2013 AT 9:23 AM

36 Replies

Tiny
HMAC300
  • EXPERT
Fuel pressure should be 55-60 psi look for a clogged fuel filter first. It should hold that for 5 minutes after car shut off. Otherwise may be the pump. Also clean the throttle plate on both sides with choke cleaner and iac hole.
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Sunday, September 1st, 2013 AT 10:41 AM
Tiny
SUPERCHRIS
  • MEMBER
  • 2002 PONTIAC GRAND PRIX
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 90,000 MILES
What is the fuel pressure supposed to be. My tested at 25lbs?
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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
WRENCHER1
  • MEMBER
Pressure 52-59 psi
KOEO Key on Engine Off

Here is a guide to help you

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Please let us know if you need anything else to get the problem fixed.
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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
2CEXPT
  • MEMBER
2002 Pontiac Grand Prix V6-3.8L SC VIN 1
Pressure 48-54 psi
KOEO Key on Engine Off

2002 Pontiac Grand Prix V6-3.1L VIN J
Pressure 52-59 psi
KOEO Key on Engine Off
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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
WRENCHER1
  • MEMBER
For 2002, I'm showing the same pressure for both engines.
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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
2CEXPT
  • MEMBER


https://www.2carpros.com/forum/automotive_pictures/12900_fp_63.jpg

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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
WRENCHER1
  • MEMBER
I see what the difference is.

It's the non-supercharged 3.8 (VIN K) that is 53 to 59, same as the 3.1. The supercharged version is a little lower.
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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
BANDITGTP
  • MEMBER
  • 1999 PONTIAC GRAND PRIX
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 135,000 MILES
I've been working on an issue with my car for some time already. I have dropped from getting 28mpg to 22 mpg. I am also getting codes for misfire and running rich. After a major tune up as well as a few other repairs (with no positive results), I have just found out my fuel pressure is 43psi when the key is in the 'ON' position but then jumps up to 83psi after I start the car. When I take the vacuum line off from the Fuel Pressure Regulator while the car is running, there is no change in the fuel pressure or the performance of the car.
Does it seem like the problem is the Fuel Pressure Regulator or is there a problem elsewhere?
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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
2CEXPT
  • MEMBER
Check the fuel return line if its clogged-up if not replace the regulator then report back asap.
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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
BANDITGTP
  • MEMBER
How would I check to see if the return line is clogged?
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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
2CEXPT
  • MEMBER
Disconnect the fuel return line on the fuel rail and apply air pressure to it, if not clogged-up replace the fuel pressure regulator
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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
BANDITGTP
  • MEMBER
Do you know if there is a trick to disconnect the return line? I was trying to disconnect the line where the steel line end and changes back into rubber/plastic line. The rubber/plastic line slips over the steel line and it has 4 clips on the inside of the rubber/plastic line that clip onto the steel line. I can't seem to get all 4 clips pushed back at the same time in order to disconnect the line.
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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
2CEXPT
  • MEMBER
Do you have vacuum on the vacuum hose to the fuel pressure regulator?
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Wednesday, December 4th, 2019 AT 2:01 PM (Merged)
Tiny
BANDITGTP
  • MEMBER
Yes there is vacuum. When the car is running and I take the vacuum line off from the regulator, there is vacuum on the vacuum line. When I remove the line there is also no change in how the car runs. I still get the same amount of pressure on the fuel rail.
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Wednesday, December 4th, 2019 AT 2:02 PM (Merged)
Tiny
2CEXPT
  • MEMBER
You probably need a special disconnect tool.

Note: When you remove the vac hose on the regulator the pressure should rise to about 8psi-sounds like the regulator
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Wednesday, December 4th, 2019 AT 2:02 PM (Merged)
Tiny
BANDITGTP
  • MEMBER
I changed out my FPR earlier today and to my surprise, and disappointment, it still didn't solve my problem. I really had high hopes that this would do the trick.

With the key turned to ON, I get closer to 48psi now compared to 43psi before I changed it. After I start the car I am getting 84psi compared to the 78psi to 84psi before I changed it. I also pulled off the vacuum line with the engine running and there was no change. I was able to position the pressure gauge so I can see it from inside the car. While the car was in gear but holding down the brake, I am able to rev the engine enough so that it bogs down. The fuel pressure is still above 80psi while the engine is bogging down.

I'm not exactly sure of the mechanics behind the supercharger but it also seems that the bogging happens whenever the supercharger is giving boost according to the dashboard gauge. Could part of the problem be that the engine is getting extra fuel because of the boost but not enough air to match and is therefore dumping in way too much fuel with out enough air to back it up? Like I said, I'm not sure of the mechanics behind the S/C but I'm grasping for straws. I still don't think this would explain the reason for such high fuel pressure.

Any suggestions would be greatly appreciated.
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Wednesday, December 4th, 2019 AT 2:02 PM (Merged)
Tiny
MASTERTECHTIM
  • MEMBER
Does this engine have a supercharger?
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Wednesday, December 4th, 2019 AT 2:02 PM (Merged)
Tiny
BANDITGTP
  • MEMBER
Yes it has a S/C. It's a 99 GTP.
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Wednesday, December 4th, 2019 AT 2:02 PM (Merged)
Tiny
MASTERTECHTIM
  • MEMBER
This car runs on very high fuel pressure when hard accelerating. There is a resister located behind the passengers side headlight that reduces voltage to the pump when running at idle to reduce fuel pressure then when accelerator is pressed fast the fuel pump relay bypasses the resister and gives full power to the fuel pump which pushes 90 psi. This is normal. However it is not normal for 90 psi when at idle and running. Does the fuel pressure stay at 90 at all times? Even at idle when hot?
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Wednesday, December 4th, 2019 AT 2:02 PM (Merged)
Tiny
YOMOMMA
  • MEMBER
  • 1996 PONTIAC GRAND PRIX
Shakes or Wobbles problem
1996 Pontiac Grand Prix 6 cyl Two Wheel Drive Automatic

i try to find the fuel pressure check port and cant find it the people at the shop said it was somewhere behind the engine but I cant find it I did find something on the passenger side engine look like it was at the end of the fuel rail but I wasnt sure it was under the power steering thing that you put you fluid in
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Wednesday, December 4th, 2019 AT 2:02 PM (Merged)

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