454 TBI lean stumble on throttle tip in - The 1947 - Present Chevrolet & GMC Truck Message Board Network

j_cst_10 · 03-21-2020, 02:21 PM

Hey guys, I appreciate any advice.

I have a 91 2500 2wd suburban (square body) 454TBI with the 4L80E trans. It intermittently develops what I can describe as a lean condition stumble (although that may not be accurate but almost feels like a carb with an accelerator pump issue). If you hold your foot on the accelerator at this point it stumbles and bucks depending on load. It appears when the truck is up to temperature. During warm up it is fine. And sometimes it doesn't do it at all!

The truck runs pretty rough when it is initially started and burbles and pops, but then smooths out and drives pretty much completely normal. You can power past the stumble if you put more foot into it.

I have done a simple tune up and replaced the temp sensor in the cylinder head and cleaned the TBI the best I could with spray cleaner.

Anybody else run into this with any of the 454's with TBI?

03-21-2020, 02:21 PM	#1
j_cst_10 Registered User Join Date: Nov 2008 Location: Cleveland, OH Posts: 592	454 TBI lean stumble on throttle tip in Hey guys, I appreciate any advice. I have a 91 2500 2wd suburban (square body) 454TBI with the 4L80E trans. It intermittently develops what I can describe as a lean condition stumble (although that may not be accurate but almost feels like a carb with an accelerator pump issue). If you hold your foot on the accelerator at this point it stumbles and bucks depending on load. It appears when the truck is up to temperature. During warm up it is fine. And sometimes it doesn't do it at all! The truck runs pretty rough when it is initially started and burbles and pops, but then smooths out and drives pretty much completely normal. You can power past the stumble if you put more foot into it. I have done a simple tune up and replaced the temp sensor in the cylinder head and cleaned the TBI the best I could with spray cleaner. Anybody else run into this with any of the 454's with TBI? Attached Images __________________ 1972 Cheyenne Super 20 Custom Camper 12 Valve Cummins/5spd manual 1972 Cheyenne Super Short Bed 557 Med Olive DK olive 1970 K5 Blazer Dark Gold 1966 Coronet 440 35k mile survivor 1991 Suburban 2500 454/4L80E 2wd 1985 Monte Carlo SS 383 Sbc, t-56 magnum 6spd and Ford 9"



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