It sounds like someone is hitting the bottom of my truck with a slug hammer when I give it gas the stops when I let off it's been going on for 3 days what is the problem

Asked by GuruKDPVB Dec 01, 2019 at 02:11 AM about the 1990 GMC Sierra 1500 C1500 SLE Standard Cab Stepside SB

Question type: Maintenance & Repair

3 Answers

It sounds like someone is hitting the bottom of my truck with a slug hammer when I give it gas the stops when I let off it's been going on for 3 days what is the problem

41,240

You will need to get under the truck to see what is loose causing the banging. Loose exhaust, suspension or driveline parts. Check the engine and transmission mounts as well.

1 people found this helpful.
103,215

My guess is your gas tank is not venting properly, when you accelerate the fuel pump pumps harder, creating vacuum in the tank that the vent system normalizes, but if it can't vent you'll get banging. Google your truck's EVAP system, you'll see a diagram showing the EVAP canister with a line for atmospheric vent, make sure that is working ok.

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