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Fuel pump pressure specs?

Tiny
LDORWIN
  • MEMBER
  • 2002 PONTIAC GRAND PRIX
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 170,000 MILES
I have a 02 pontiac grand prix 3.8 V6 K vin. Ive been having truble with finding the problem with. The car will fall flat on its face no power and some times will quit. When all this happens the gas gage will not work corectly thats why Im thinking fuel pump. But at the same time the RPM gage will drop off to nothing and not work eather even if the car stays running. I checked the fuel pressure at the rail and its running 40lbs and I know the spic is around 55 lbs is it most likly the fuel pump or do I have something else going on?
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Tuesday, October 5th, 2010 AT 5:10 PM

11 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Yoru fuel pressure should be 53-59 p.S.I. So if you are at 40 it's not enough. Change your fuel filter first and see if it goes up. Bu tlike you suspect it is likely your pump. The pump is an assembly with the gage sender included it's around $485 retail.
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Saturday, October 9th, 2010 AT 7:23 PM
Tiny
COLCHASE
  • MEMBER
  • 1 POST
  • 1999 PONTIAC GRAND PRIX
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 140,141 MILES
I replaced my original fuel pump because my fuel gauge did not work. I installed the fuel pump, but it would take a few seconds to start up after this. I let it go for a few weeks and then decided to pull the pump again to see if I can notice anything wrong. There was a small hole in the pick up tube so I replaced it, but it still takes a while for it to fire up. It used to fire up as soon as you hit the key, but since the fule pump replacement, it takes a while and it sounds as if it getting loaded up when it does start and has a smell to it. Once it starts, it works great. Soemtimes if you hit the key 3 or 4 times at one second intervals it will start rather then letting it crank for 7-10 seconds. Seems like it losing it prime if that possible.
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Saturday, March 20th, 2021 AT 7:33 PM (Merged)
Tiny
MERLIN2021
  • MECHANIC
  • 17,250 POSTS
Go here and checkout

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

Do a leak down test, see how far and fast the pressure drops, and check the pressure regulator.
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Saturday, March 20th, 2021 AT 7:33 PM (Merged)
Tiny
LILANGEL23
  • MEMBER
  • 2 POSTS
  • 1996 PONTIAC GRAND PRIX
Every once in awhile when I am driving the RPMs would be around 2000 then drops suddenly like my engine is not getting any fuel. The car acts like I am tryin to drive a manual stick shift for the first time when it does it but never stalls and the service engine light does not kick on. The fuel pump and fuel filter are new was just replaced not to long ago.

When the FRP was checked there was no fuel present.

Also the fuel pump makes a loud whinning noise which according to the auto parts store some fuel pumps do that. Is that true?

Would the MAP Sensor be causing this problem or would it be the fuel pump relay thats causing this?
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Saturday, March 20th, 2021 AT 7:33 PM (Merged)
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,549 POSTS
Check fuel pressure with a mechanical gauge, should be above 40psi, and when you "blip" the throttle it should go up 5psi or so.

Some pumps are noisier than than others, but you should not be hearing "a loud whining noise".

A bad relay would normally shut fuel off and engine would stop.

A MAP sensor would set an error code and engine would barely run (fuel mixture would be very rich).
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Saturday, March 20th, 2021 AT 7:33 PM (Merged)
Tiny
DUDUE45
  • MEMBER
  • 3 POSTS
  • 1994 PONTIAC GRAND PRIX
  • 150,000 MILES
1994 pontiac grand prix. Not sure if I have a vats problem or a clog in my fuel pump strainer when I turn key security light comes on for 5 seconds then goes out. No blinking. The car starts and runs for a few seconds then dies. The fuel pump is working. I have pulled the fuel line at the fuel filter and turned the key to on position no gas when I turn key to start gas pumps when I release the key fuel pump stops working.
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Saturday, March 20th, 2021 AT 7:33 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Thats' becaue the pump only works on initial key up and the oilpressure sender takes over after a start. But jump the relay and see if it pumps ok bu tleave everything connected. You will need 41-47 psi from teh fuel rail to run.
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Saturday, March 20th, 2021 AT 7:33 PM (Merged)
Tiny
DUDUE45
  • MEMBER
  • 3 POSTS
Not sure are you telling me to bypass the fuel pump relay or bypass the oil pressure sensor? I did bypass the VAT system and still the same thing the car will start and then idle for about 5 seconds then shut off. The fuel pump is wroking hard in the tank but pumping gas. Thanks for the help
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Saturday, March 20th, 2021 AT 7:33 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
Best thing to do is check the fuel pressure first on start up then after car runs. When the key goes on the relay sends power to the pump and it shodl give you pressure. After the car starts power is sent through the oil pressue sending unit to the pump. If it shuts off after starting then your oil pressure switch may be bad, check that.
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Saturday, March 20th, 2021 AT 7:33 PM (Merged)
Tiny
DUDUE45
  • MEMBER
  • 3 POSTS
Ok is that something I should just replace in order to "check" it? Or can I jump a wire across the two terminals?
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Saturday, March 20th, 2021 AT 7:33 PM (Merged)
Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
You can jump it but make sur eyo have theright wires.
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Saturday, March 20th, 2021 AT 7:33 PM (Merged)

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