Fuel pressure specs

Tiny
MFIG
  • MEMBER
  • 2000 PONTIAC GRAND AM
  • 6 CYL
  • 105,000 MILES
Car is running rough. What is the fuel pressure specs for my car listed above?
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Saturday, April 29th, 2017 AT 4:20 PM

6 Replies

Tiny
CARADIODOC
  • EXPERT
Please list the engine size when you have an engine-related problem. Rough running is usually the result of worn spark plugs and wires. Some GM engines do run poorly or won't even start when fuel pressure is just a few pounds low, but that applies more to truck engines.

Fuel pressure for the 2.4L is 52 - 58 pounds.
Fuel pressure for the 3.4L is 48 - 55 pounds.
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Monday, May 1st, 2017 AT 7:23 PM
Tiny
MFIG
  • MEMBER
Thanks for the information. The engine size is 3.4L. Fuel pressure is 44 pounds. It starts up rough. I need to keep pressing the accelerator to keep the engine running. After awhile it will run on its own. I am thinking it is the fuel regulator. Any suggestions would be appreciated.
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Thursday, May 4th, 2017 AT 6:54 PM
Tiny
CARADIODOC
  • EXPERT
Before you get too involved looking for elusive stuff, did you consider worn spark plugs?

Four pounds low on fuel pressure will not be an issue on other cars, but to rule that out on a GM product, when the rough running is occurring, look for the fuel return line where it is rubber between the fuel rail and the body. Pinch that off with a hose pinch-off pliers. Fuel pressure will increase if the pump is able to develop that higher pressure. That will prove the pump is okay. Those cause a lot more trouble than regulators do.

GM has had a lot of trouble with their fuel pressure regulators leaking, but that also applies more to truck engines. Pull the vacuum hose off at the regulator and look inside it. If it is wet with gas, replace the regulator. Pulling the hose off should also make the fuel pressure go up. If it does, the regulator is working.

Now for the more elusive cause of rough running on GM vehicles. Unplug the small one, two, or three-wire plug from the back/side of the generator. If the rough running clears up, I will discuss that in more detail.
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Thursday, May 4th, 2017 AT 8:09 PM
Tiny
BAKAN1313
  • MEMBER
Okay, so I want to know about the 1, 2 or 3 wire plug behind generator and why it would clear up if you do not mind.
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Friday, August 3rd, 2018 AT 8:23 AM
Tiny
DANNY L
  • EXPERT
Hello, I am Danny.

To look up specifications we would need all of your vehicle information. Thanks for using 2CarPros.

Danny-
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Friday, August 3rd, 2018 AT 12:40 PM
Tiny
CARADIODOC
  • EXPERT
I just typed a really long reply to explain it, but I thought your eyes might glaze over. I will post it if you are interested.

GM has a really big problem with their generators starting with 1987 models. They develop huge voltage spikes that can damage their internal diodes and voltage regulator, and interfere with computer sensor signals. This becomes much worse when one of the six internal diodes fails. By unplugging the smaller connector on the back of the generator, you are simply turning it off, along with any voltage spikes it might be developing. If those spikes are the cause of an elusive running problem, it should clear up on a short test drive.
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Friday, August 3rd, 2018 AT 12:51 PM

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