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Engine Bogs Down/Miss/Backfire 1999 5.7 Suburban


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firecap's Avatar
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April 12th, 2009, 3:35 PM   #1  
Engine Bogs Down/Miss/Backfire 1999 5.7 Suburban

I have a 1999 Suburban, 5.7 Gas. It has 127,00 miles on it. I have had to replace the fuel pump twice. Once about 18 months ago and again 6 months later. The replacement fuel pump is an Airtec Fuel Pump from Autozone. The truck runs fine while driving around local or on short trips. But if I take it on the highway for a trip longer than and hour or so, it begins to loose power gradually. It will run slower and slower and will bearly pull a hill. When you press on the gas pedal, it will bog down worse and backfire. If you back off the gas pedal it will take off again but with hardly any power. I have found that if i turn the engine off for just 2 or 3 seconds and start it back up, it will run better for a short distance, maybe 5 or so miles and it will start it again. The only time that it has ever set a code, it was for "Multiple Misfire", which doesn't help alot. I have seen other people post this same problem a couple times but no one has ever posted their solution.

Things already checked:
Recently replaced plugs, wires, cap, rotor, air-filter, fuel filter. Have also ruled out igniton coil and MAF sensor.

This problem has been going on now for some time but I don't want to start throwing money at this thing until I know where to throw it. I have taken it to a mechanic but it will never run bad when he has it, even after he has driven it around for awhile. It normally starts missing after being on the road between 1 and 1-1/2 hours.

If anyone has any ideas or has experienced this problem, I would love to hear from you.

Thanks!

 
MDTAHOE's Avatar
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April 13th, 2009, 5:42 PM   #2  
What is the fuel pressure now? Autozone parts are known to be not very good quality.

 
firecap's Avatar
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April 13th, 2009, 8:12 PM   #3  
The fuel pressure usually runs between 50 and 55 psi. When the truck is running good, you will see the pressure increase to about 58 upon acceleration. When it is not running good, the pressure does not increase at all upon acceleration. I believe my problem is the fuel pump. I talked to Autozone today about it. The pump is still under warranty, but I do not want another Autozone Fuel Pump. This time I want the Delphi Fuel Pump. They have agreed to refund my money for the pump if I bring it back along with a receipt for the Delphi pump that I purchase elsewhere. The new fuel pump should be installed this Wednesday. I will be taking a trip in the Suburban next week. This should be a good test for it to see if this cures my problem. I will post my results when I get back.

Thanks,

Firecap

 
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May 3rd, 2009, 8:34 PM   #4  
I had the new Delphi Fuel Pump put in about 2 weeks ago. I have since taken two trips to the mountains in the Suburban, once while pulling a trailer. The Suburban ran great on both trips. This is the first time since this past November that I have completed a trip of more that 2 hours that I did not start experiencing the bogging down and lack of power. I now feel confident that the fuel pump was my problem.

Firecap

 
evans906's Avatar
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May 10th, 2009, 8:45 AM   #5  
Try replacing the fuel filter. I replaced my fuel pump with a AutoZone pump and I haven't had a problem with the pump. But I also replaced the fuel filter at the same time. What you are doing is putting a strain on the fuel pump and it will eventually go out again.

 
firecap's Avatar
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May 11th, 2009, 8:52 AM   #6  
I forgot to mention on my first post that I had replaced the fuel filter. That was the first thing I did when I began having problems. I am pretty sure that the fuel pump was my problem.

Thanks,

Firecap

 
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May 11th, 2009, 10:51 AM   #7  
Did you have the pump replaced at a shop? I wonder what they charged you for the pump? If you check out www.rockauto.com you can buy a Delphi pump part #FG0092 for $262.89 plus shipping and have a shop install it for you. Just a thought. Glad everything is well.

 
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May 11th, 2009, 12:36 PM   #8  
From my experience, theres not an aftermarket fuel pump out there that does better than OEM. Unless of course you are going for performance..

 
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