What could be causing my 2000 Chrysler 300m to start up but I have to pump the gas to keep it running and when i do this it backfires

Hello Janet Garman,

That was exactly how my '75 Rancher behaved when the muffler collapsed (inside)... or my '95 Jag almost 20 years later when the catalytic converter clogged the exhaust... It continued to run...
but threw DTCs (trouble codes) on OXYGEN, FUEL, air & throttle issues... No clear point to EXHAUST.

I know of ne elegant way to prone it ... but to open the exhaust above the catalytic converter...
... Hope this helps.

It is quite dangerous to run in this condition... but at least you know what has to be replaced BEFORE RUNNING IT again.

If you are going to fix it yourself... SOAK those BOLTS up greatly with penetrating oil before removing them. Bolts can be re-used.

Check out your exhaust elements (prices) even if you are having the work done... on rockauto.com

2000 CHRYSLER 300M 3 5L V6 Catalytic Converter RockAuto

Hi sounds like a blocked main jet in the carby :::: a good tune up might fix youre problem with it backfiring ::::,& replace the fuel filter : Cheers