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1999 K1500 4X4 Suburban fueling issues

Tiny
1999CHEVYBURBDUDE
  • MEMBER
  • 1999 CHEVROLET SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 194,000 MILES
Hello, I just purchased my 1999 Chevy Suburban 4x4 K1500 5.7L in October of 2010. I've been slowly working through issues with it and have one last issue with the fuel consumption. It seems as if the truck consumes more fuel at idle (I can see the gas hand move if it idles - just setting, not driving, long) than while driving at freeway (70mph) speeds. Truck lacks acceleration during passing maneuvers. It doesn't buck and***** like it did when I got the distribur wet, just slow acceleration from 60 or 70 mph. Also, when I stop and park the truck I smell gas fumes, but there are no leaks externally. Could my spider system be leaking down when I park the truck? Would a pressure test show me this? Also, would replacing the fuel filter have any effect on this?
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Wednesday, January 26th, 2011 AT 2:50 PM

8 Replies

Tiny
MMPRINCE4000
  • MECHANIC
  • 8,549 POSTS
A fuel pressure test will tell you of any pressure loss in system.

If you have not replaced fuel filter, I would.

The pressure regulator could be leaking.

Another possibility is that if it sat for more than a month, the fuel system may have gum and varnish. So I would also try a fuel system cleaner like SeaFoam.
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Wednesday, January 26th, 2011 AT 6:18 PM
Tiny
1999CHEVYBURBDUDE
  • MEMBER
  • 5 POSTS
Ok, I have the filter already. Will replace today or tomorrow. I have run Lucas fuel treatment through the engine on just about every fillup. Is Seafoam better? Is there any way to tell if the regulator is leaking before removing the upper intake? I just replaced the intake manifold gaskets, and everything looked ok then (after I cleaned it up).
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Wednesday, January 26th, 2011 AT 7:32 PM
Tiny
1999CHEVYBURBDUDE
  • MEMBER
  • 5 POSTS
I've changed the fuel filter and performed a pressure test. KeyOnEngOff: Pres. Increases to 62psi then drops to 58psi after 2 sec. When the pump shuts off.

KeyOnEngOn: Fuel pressure ranges from 62psi on acceleration to 54psi with the engine at idle.

After engine shuts down, the pressure bleeds down significantly - @ 35psi after about 20 minutes. Should this happen? What would cause the pressure to drop like that?
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Thursday, January 27th, 2011 AT 5:52 PM
Tiny
MMPRINCE4000
  • MECHANIC
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The pressure is Ok, 35psi in 20 minutes is normal.

If it dropped to 35psi in 20 SECONDS, then you would have a problem.

I would next remove MAF sensor and clean with Mass Air Sensor cleaner.
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Friday, January 28th, 2011 AT 3:26 PM
Tiny
1999CHEVYBURBDUDE
  • MEMBER
  • 5 POSTS
Ok, I'll try that. How would this cause the fuel smell after shutoff?
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Saturday, January 29th, 2011 AT 2:57 AM
Tiny
MMPRINCE4000
  • MECHANIC
  • 8,549 POSTS
You could have an injector seal bad.
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Monday, January 31st, 2011 AT 3:13 PM
Tiny
1999CHEVYBURBDUDE
  • MEMBER
  • 5 POSTS
Is there any way to check for this or could the regulator be leaking and how do I check for this?
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Monday, January 31st, 2011 AT 10:05 PM
Tiny
MMPRINCE4000
  • MECHANIC
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Remove the vacuum line to regulator, if gas is present, then FPR is ruptured.
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Wednesday, February 2nd, 2011 AT 1:55 PM

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