GMC Sierra Acceleration by itself

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    • #10972

      2006 GMC Sierra. I just replaced the fuel pump relay, the fuel pump, and the whole sending unit to the fuel pump. The pickup now runs but with an issue. It idles at higher rpms and when it’s in drive it keeps accelerating whether I push on the gas pedal or not. What could possibly be the problem and is it an easy fix or not? I know a little about my pickup but nowhere near a professional mechanic.

    • #12665


      I’d check the throttle linkage and surrounding area for anything hanging up or causing a binding situation. Also, you could have the throttle body butterfly sticking due to carbon build up, which a quick cleaning can fix. Open the blade and spray carb or brake cleaner on a rag and wipe the throttle bore and plate real good. Take it for a drive and stomp on it a few times to blow it out.

      Other than that, you could have a vacuum leak causing it to idle high and accelerate on it’s own.

    • #17625

      I replaced my distributor in accordance with the tech manual but the truck will not start. I have a spark. Was the tech manual wrong I brought the the #1 cyl up dropped the distributor to the dot on the rotor base was pointed to the #1 cyl, is there a different way to accomplish this? Thank you.

      RE: Did the truck start and run before you replaced the distributor?

      Yes but it ran poorly.

      OK. You have done it correctly but maybe have a different problem. If you were off a tooth or so the engine would still start but missfire. I would check for proper fuel pressure. Next, watch the rotor on the distributor and turn the crank pulley with a wrench and see if there is a lot of slop between turning the crank pulley and when the rotor starts to turn. If there is then you have a worn timing chain and / tensioner.

      Hello, my engine idles a little rough and when I accelerate it backfires and will die no engine codes show up.

      Check for a vacuum leak. Also, do a complete tune up with spark plugs, plug wires, distributor cap and rotor. Sound like a common problem of that GMC truck where the distributor cap and rotor are worn out or corroded.

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