1999 Chevy Suburban runs rough

Tiny
TERESCLA
  • MEMBER
  • 1999 CHEVROLET SUBURBAN
  • V8
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
My suburban was hard to start so we changed the fuel pump. That didn't fix the problem. We changed 2 fuel injectors because the computer was showing a misfire on 1 and 3. That didn't work. We changed the fuel filter and the fuel regulator and that worked. Now a new problem has started. When I first start my suburban and push the gas it acts like it can't get enough gas and sputters for about a block then it acts like it releases and it runs fine until the next time I start my car. The service engine light is on and the computer is now showing bank 1 and bank 2 running lean. Please help.
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Wednesday, March 5th, 2008 AT 6:07 PM

11 Replies

Tiny
SERVICE WRITER
  • EXPERT
Check your fuel pressure again and volume. May be a defective fuel pump.
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Wednesday, March 5th, 2008 AT 8:08 PM
Tiny
TERESCLA
  • MEMBER
What should my fuel pressure be?
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Thursday, March 6th, 2008 AT 7:03 PM
Tiny
SERVICE WRITER
  • EXPERT
Not sure which motor you have

5.0 and 5.7 should be 60-66 psi
4.8,5.3,6.0 and 7.4 are 55-62 psi

If your pump had the Metri-pack 150 connector (shown below) it should have been replaced at the time the pump was done.


http://www.2carpros.com/forum/automotive_pictures/30961_mtri150_1.jpg

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Thursday, March 6th, 2008 AT 7:42 PM
Tiny
SERVICE WRITER
  • EXPERT
It is in the air duct going to the throttle body. Easy enough to test. Disconnect the harness from it and start the engine. If the engine starts. Relace it.
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Saturday, March 8th, 2008 AT 7:40 PM
Tiny
TERESCLA
  • MEMBER
I'm going to replace it tomorrow for 140.00 and I'll let you know if it helps. Thanks again for the advice.
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Saturday, March 8th, 2008 AT 8:28 PM
Tiny
SERVICE WRITER
  • EXPERT
Before you do this.

Understand that I found this under a no-start condition procedure. There is no test that I could find for that sensor. That sensor may not be bad.

Before you buy it, I would rather have the code number you pulled and check the flow chart on it. I have had the testing information not be accurate in the past. Maybe the maf is bad and is one possible solution, but so would an air leak occuring after the sensor in the duct work or an intake gasket leak.

$140 is a pretty strong leap of faith. That connecter I mentioned earlier may also be playing into this.

If I was going to try a maf sensor I would probably stop at a junkyard and get one. If I went for a new one, I would ohm out the okd one and then ohm out the new one at the parts store before I was to buy it. These are not a terribly common thing on these in my experience.
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Sunday, March 9th, 2008 AT 5:44 AM
Tiny
TERESCLA
  • MEMBER
I went and bought a new MAF and changed it in the parking lot and it made the suburban run worse so I went and got my old one back. I made a 6 hr trip after that and it still was sluggish when I first started to go and it jerked after climbing a hill. The service engine light was still on the whole time. Then yesterday I started the car and the service engine light was off but it still runs sluggish at the beginning then it runs fine. I'm running out of ideas. I have changed the gasket you where talking about and my problems with it running rough didn't start until I changed the fuel regulator( which fixed the starting problem). I don't know what if I have that connector you are talking about. I have a 5.7l engine. It doesn't look like anything I've seen so far.
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Wednesday, March 12th, 2008 AT 10:47 AM
Tiny
TERESCLA
  • MEMBER
Oh yea I didn't tell you that I replaced the fuel pump a couple of days ago (again) and that wasn't the problem either.
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Wednesday, March 12th, 2008 AT 10:50 AM
Tiny
SERVICE WRITER
  • EXPERT
What codes numbers are listed in the pcm?
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Wednesday, March 12th, 2008 AT 10:52 AM
Tiny
TERESCLA
  • MEMBER
All we know is what the guy told us which was bank 1 and bank 2 lean. No number codes.
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Wednesday, March 12th, 2008 AT 8:15 PM
Tiny
SERVICE WRITER
  • EXPERT
I guess would start looking for a vacuum leak with that much info. You can spray carb cleaner around the plenum and intake to see if an idle change happens. Propane will also work. Unlit of course.
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Wednesday, March 12th, 2008 AT 8:41 PM

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