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Loss of power at WOT

desperado58

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desperado58 Enthusiast

desperado58

Posted
Posted

I have a 1996 GMC K1500 Sierra Extended cab with the 5.7 engine. The engine starts and idles fine. It basically runs fine, except when I apply full throttle. It seems to be alot of noise, but no go. I will get error codes that indicate low voltage in the upstream O2 sensors, which means a lean condition (I believe they were P0131 and P0151). I've replaced the upstream O2 sensors, the Throttle Position sensor and the fuel filter and am getting the same results. The engine seems weak even when I rev the engine up while in park. I'm thinking it is fuel pressure related because the engine runs great except for WOT. Any ideas or thoughts are welcomed. Thanks

toddgotfish Enthusiast

toddgotfish

Posted
Posted

also check the usuals

air filter plugs and wires

and track down your battery and engine grounds

it does sound like you may have a problem with your

throttle body or your fuel pump

do oyu know anyone to chek the fuel pressure for you

 

Todd

sonjaab Senior Enthusiast

sonjaab

Posted
Posted

DES......Sounds like your Cat. converter is plugged !

Take it to any major muffler chain....They will test

for FREE. Try that before you throw parts at it !

........geo

desperado58 Enthusiast

desperado58

Posted
  • Author
Posted

I don't have anybody that can check the fuel pressure, other than possibly doing it myself. I don't think this model has the "schrader" type valve since there isn't a fuel rail. The wires, distrib cap, plugs, etc. are fairly new. Hadn't thought about the cat converter being plugged. Thanks

  • 4 weeks later...
desperado58 Enthusiast

desperado58

Posted
  • Author
Posted

Well, I broke down and took it to the dealership. The culprit was the fuel pump. $500 plus to fix. I went ahead and let them do it. I'm tired of messing with it. I had replaced all of the usual and had narrowed it down to the fuel pump. They just confirmed it. Thanks for all the input.

k1500chevy97 Senior Enthusiast

k1500chevy97

Posted
Posted

I had that same problem on my 3/4 version of the 350 .

 

I just replaced the fuel filter and problem went away (even though i just replaced it back in march :chevy::flag: )

gonna have to have someone clean out these large fuel tanks here on the farm :(

varmint2506 Enthusiast

varmint2506

Posted
Posted
Well, I broke down and took it to the dealership. The culprit was the fuel pump. $500 plus to fix. I went ahead and let them do it. I'm tired of messing with it. I had replaced all of the usual and had narrowed it down to the fuel pump. They just confirmed it. Thanks for all the input.

Couldn't get to reply in time but, my friend’s truck did the exact same thing and it was the fuel pump. It took us a while to figure that out since the truck would idle fine and rev fine just wouldn’t do either in gear.

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