stumble on accel.... tbi350

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taylor

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ok guys this is my problem i have been battling for about a year now... i have a 1995 k1500 rcsb 350 tbi auto.. headed uphill kick it down a gear, rpms 3k or so cuts out and starts the stumbling, shifts into od still stumbles untill i let off the pedal. thats running about 50-60 mph. on the hiway it will do it every so often at 75+ mph. and if you really mash on it runs light a bat outta hell to 80 or so the starts to stumbling bs... this is what ive do to it so far, both injectors, fuel presser reg, fuel pump, map, cap rotor plugs wires, fuel filter, cat removed coolant temp sensor, pcv valve checked all vac lines look good. engine is all stock with flowmaster muffler. trans shifts great. front end tight. im pulling my hair out. truck has 155k new engine at 99k by gm. any help will be awesome. i tired of chunking parts at it....
 

matt sorrentino

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I had a similar problem on my 94 c1500 350 tbi . Bought a new tbi rebuild kit and a new TPS (throttle position sensor) and took care of that issue. Hope it helps
 

slowburb

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Stumbling is either timing or carburetion. Instead of throwing more parts at it, fully clean the throttle body assembly. Gotta be cheaper than a Delco TPS.
 

taylor

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timing is set to zero with the brown wire unpluged. tbi has been cleaned and rebuilt...
 

someotherguy

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Before throwing any more parts at it, try this:

Unhook, and plug, the vacuum line coming from the TBI to the EGR solenoid. Try running it.

If this doesn't net you any different results, buy a couple EGR gaskets (they're cheap) and use one as a template to make an EGR blockoff plate out of scrap metal. Doesn't have to be perfect, just roughly the shape of the gasket with a couple holes drilled so you can cinch it down. You can buy a blockoff plate too, but easy enough to make one and they're not always available locally anyway.

If you use a little anti-seize lube on both sides of the gasket, you'll be able to re-use the gasket, too. Put this sucker on and try again.

If the blockoff plate helps, your EGR valve probably has a broken internal spring allowing it to open when it shouldn't, causing a lean condition. If you replace it be sure to get the correct one and stick to ACDelco or Delphi only; totally avoid the parts store brands, trust me.

Your symptoms don't exactly fit "bad EGR" but it's a possibility, and it costs almost nothing to rule it out.

Richard
 

taylor

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WHAT DO YALL THINK ABOUT THE DIST. NOT ADVANCING? WHAT CONTROLS THE TIMING ADVANCING? WHAT IS THE SENSOR ABOVE THE STARTER IN THE BLOCK WITH ONE WIRE? I DRIVE 50 PLUS MILES A DAY THIS IS MY ONLY TRUCK IT IS DRIVING ME NUTS!!!! LOL
 

rolla711

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Nvm just read you replaced the fuel pump

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