I put a new muffler on the truck the other day and drove around the block a few times and when it was idleling in the drive way it started running rough until it stalled and then wouldnt start at all. the cam pos sensor came up so i check all connections , wires etc.. all good. so i replaced the sensor cleared the PO340 code and still nothing. i checked the coil,fuel pressure all checked out ok..i guessing the muffler thing was a coincidence ..now im stuck ..please any suggestions ...

 

Gotta see if you have fuel pressure (45-50 psi) and spark. Turn key on and listen for fuel pump. Swap ASD relay for another relay and see if it kicks off.

 

My bet is, when you replaced the muffler, (the already clogging cat, due to bad plenum gasket) knocked some of the honey comb loose in the cat. Unscrew the precat o2 sensor and see what it does. Then read the plenum thread on top of the forum.

 

I guess definine what you mean by "wouldnt start at all....and still nothing...." would help. is it cranking and not starting, or is it "doing nothing" because they are not the same thing. If it cranks but won't start, then zman's best bet is probably the best bet out there!

 

fuel pressure,and spark are good and switched out the asd relay still nothing..its turning over just not firing. and to Zman17 i put a hughes plenum kit in about three months ago and it wasnt leaking but put it in anyways..didnt check the o2 sensors though figured a code would come up if they went bad..

 

ill go pull the precat o2 now....

 

OK then, I know your probably posting from a phone. If that's the case, add that small bit of info to your sig and profile. This way we all don't have to guess and make assumptions. And no, the o2's don't always throw a code. The reason behind "unscrewing the the precat o2 is to see if the exhaust is clogged in any way.

 

no go..still not firing..after trying to start it for a seconds it diesels up when i let of the ignition.bit its not consistent.and no cels yet..ill update my profile too..sorry

 

If cat isn't clogged........CKS or CPS? Disty or rotor? If it is diesleing, the firing isn't timed correctly somehow. Maybe disconnect battery and reset PCM.

 

Sorry, but you need to verify fuel pressure and spark. I'd try a new coil, but I don't want to spend your money.