2001 silverado 5.3 missing when pedal is depressed

[Daner]

Hello everyone.

Here is the story.

Go out to move the truck so I can mow the lawn. It starts but it is missing and shaking idle about 3-400. I messed around with the throttle for a while and it seemed to come out of it while idling. Now any push on the gas and it starts missing and will keep missing until I let off. I can feather it up to higher rpms and it will run fine but any semi quick throttle application almost kills it.

It has a new fuel pump 15k ago and basically haven't done anything to it since I bought it besides reg maintenance about 35k ago. Truck has around 136k miles on it.

One other thing to mention somebody just filled the tank up with gas it was less than a 1/4 tank last time I drove it.

I'm going out to do some more troubleshooting now.

[gmclowsierra]

Check fuel pressure relief valve for leakage.
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[truckdude239]

What brand fuel pump.p did you use? Its not uncommon for the cheaper aftermerket pumps to fail quickly where as an ad demo or sephi pump will last a long time
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[Daner]

Checked relief valve and there is no leakage when the vacuum line is removed.

I didn't put in the pump so I don't remember what the brand name was however it had a long guarantee on it. It was expensive too. I think $400+.

Thanks for replies. Going to pick up a service manual tomorrow.

[Daner]

Put a pressure gauge on and here are the results.
54 ign on 55-62 is spec according to my tech manual
50 at idle
60 when vacuum line from relief valve is removed.
When you hit the throttle, pressure goes to 55 but engine still almost dies.
I installed a new fuel filter. Made no difference on my readings.

I put new plugs and plug wires on before I did any testing. It was one of those things I've been meaning to do anyway. It idles good now.

I'm thinking maybe bad gas?

[Daner]

Well problem resolved.

Bad Gas.

Dad's 93 Ford wouldn't start and my 67 chevy was having the same missing on acceleration problems my 2001 was.

Anyway after siphoning out a full tank of gas it runs good!

This was the first gas I sucked out. It gradually got better but I didn't want to take any chances. Don't worry the dirt was in the bucket.

[hugger6933]

My first thought before I could get to the reply was bad gas, bad dist cap [joke]or wires although it seems kinda early for them to be going bad but then again if it has tires or ti##ies it is gonna cause problems.