Went out to start my 1997 4x4 5.9 one morning it would turn over but not start. Replaced the cat and new muffler,new up stream o2. It will run for 300 miles then start spitting and sputtering and backfiring then die. If I reset the comp it will run fine for another 300 miles then same thing over.The comp is not turning on ce light. Can anyone please give me some advise on this, where to start, anything!!!!
Thanks

 

How many miles on the truck? Have you looked at your plenum? Have a look at your plugs. Are they getting oil fouled? (if they are, that will destroy your new cat, and O2 sensor.....)

 

it kinds sounds like the crank position senor. have u checked to see if there anycodes with a scanner cause sometimes mine will have a code but the check engine light will not be on

 

300 miles? your out of gas

 

There are no codes, I wish it was as simple as out of gas.the truck has 145k miles on it.If it is the TPS would it even go the 300 miles before it started acting up? It is like the comp does not pick up a problem until the 300 mile mark then wham it starts up.

 

Any correlation between fuel level, and how it runs? Wonder if there isn't something in the tank that is restricting the pump intake.....

Shutting off the truck, and restarting doesn't help? But, resetting the PCM does?

 

Are you going 300 miles and then putting gas in it? Or are you putting gas in it during the 300 miles?

 

that is the big question. Driving a truck with less than 1.4 tank of gas puts a lot of stress on the fuel pump.

At your mileage, the fuel pump might be suspect.

Do a fuel pressure test. Should be around 49 PSI with the engine idling.