Backfire from manifold?

Question

Hello i was looking at my car this morning and i revved up the engine by the trottle body and it made this loud THUMP noise. it sounded like it came from the drivers side manifold?? the car is burning rich right now.im waiting on o2 sensors to come in. . could this be y it made that noise???? its a 94 chevy camaro 350 LT1.. Thank you

Answer 1

Def. a misfire.  Try it again, and see if it thumps again.  If so, check to make sure your plugs are all good.  That's a simple fix.

Answer 2

its the fuel regulator that is bad. it is mounted on the side of your injector pack which requires you remove the intake to get to it. the regulator goes bad and starts leaking and dumps fuel into the back four cylinders of the engine. the thumping your hearing is the extra fuel thats not burning in the cylinder but burning off in your exhuast manifolds. if you dont replace it it will scorch your poppet valves and possibly catch your car on fire.

Answer 3

sounds like a misfire. check all cylinders are firing, if not that will be your problem