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2001 Pontiac Grand Am Misfire/backfire

Recieved the vehicle as a gift from family about a year ago, it had been sitting on a pno since 2011, we moved it with some help, so far we have replaced Spark plugs/wireset, Oil filter, map sensor, battery. We used an ob2 which led us to replacing the map sensore which was the only code at the time which was then replaced by misfires, at the time the vehichle could start if only a bit rough and idle without shutting down, Now it barely starts and wont stay on for more then maybe half a minute before dying, we are headed towards replacing the fuel pump next, but before we do i would like some feedback from someone more savvy than me, Could this also be caused by bad gas as it has not been replaced since we moved it, i want to be sure before i spend to much on a possibly simple fix.

What’s a pno?

If the gas is from 2011, it is almost surely bad, beyond viable for running the car.

Drain the gas FIRST. That stuff in the tank is 8 years out of date! Add fresh gas with some injector cleaner.

Don’t worry about misfire or really anything until you do this. You should not have even started it until you did this. Run at least a half tank through before clearing the codes and watching for new ones, if any, to pop up.

Will do, Thank you. im not very mechanically good at this stuff, and most of the help i have been getting is from other family who are more or less self taught in this stuff.

Gotta agree. The MAF could have changed the fuel ratio which is now causing too lean a mixture to run with the bad gas. I will say though I did have a bad MAF out of the box. It ran OK but ran way rich. Before replacing the pump, you really first need to listen to see if the pump runs or not when the key is first turned to start, then you should really do a fuel pressure test. Can’t do a complete test though without the engine running. Yeah but fresh gas first. (See Tester post about 10-15 years ago)