Please bare with me as this will be a long post. I like to give all the history i can in order to get more accurate responses
I have a 96 dodge Dakota 3.9l 132k miles
OK so my truck has sat up for about 5-6 years driving once every few months just to drive it. before that we had to replace the camshaft sensor once a year. decide to put a little TLC in it as my son turns 16 next month and out of all the vehicles we have he wants to drive this one. (proud dad moment)
replaced the battery and it started and drove fine. then it started backfiring and would cut off. i noticed a very large gas smell if i let it sit for a few hours i could get in it and it would start. run fine for a while then backfire and shut off. rinse repeat.
while trying to figure this issue out i was in my drive way revving the engine and it back fired 2 times, the second sounded like a shotgun going off and it blew the pass side exhaust manifold off. now i can get it to try to start and it will run ruff as all get out for about 2-3 seconds then cut off. bad smell of gas again. i have replaced the camshaft sensor ( i checked the wires using a meter to make sure there was no issue with them) the idle air sensor the TPS the plugs the wires the dist cap the starter the PCM the ignition coil made sure plug 1 was TDC and made sure sure the rotor button was on 1 checked the timing marks on the vibration damper it was off by 4 degrees. i do have spark and made sure the new coil was good. I really would like to see if there is a way to check the mechanical timing without having to take the front of the engine off first is that possible and if so how would i do that . If anyone has any other suggestions i am all ears. I have put a ton of money into this thing and really don't want to have to throw it all away. i will be putting a fuel pressure tester on it this afternoon. Everyone thank you for any and i mean any advice you can give me. I want to make sure this truck makes my son just as happy as it has made me over the last 12 years.

 

It's running excessively rich. I would have a look at the temp sensors. (you have two, one for the gauge, one for the PCM, the two-wire sensor is for the PCM.) If you have a scanner that will read live data, have a look at what the pcm thinks engine coolant temp is, and also intake air temp. See what ya got.

 

I have no codes in my obd2 port. Wouldn't it throw a code if it was the sensor? Tested continuity on the wires to the temp sensor today and that's all good. But I can't keep the truck running long enough to test the actual sensor. I tried to get a resting reading (while it's cool) but I got nothing. I don't know if it is an open circuit that closes or a closed circuit that opens.

 

Neither. It's a resistance that changes as the temperature changes.

Have you tried the key dance? You should get at least a 55, End Of Codes.

And no, the sensor can be wrong, but not wrong enough to toss a code.

RwP

 

I have not done the " key dance" yet honestly until yesterday reading through the forums i hadn't thought about that. I got a little excited last night and started taking the exhaust off at midnight. thinking that if the cat is clogged it wouldn't blah blah blah sometimes whiskey tells you things that are not really smart...... so ill try the key dance this afternoon. here is to hoping me taking the exhaust off didn't hinder it in some way.

 

did the key dance yesterday and got an 11 and a 12. the 11 finally went away after a few times of me trying to start it. i disconnected the exhaust fully yesterday and it would start and run for about 30 seconds then choke off and not restart. was starting to think it was a timing issue but now Im not to sure.

 

11 is a crank or cam sensor not sensed.

I'd really be looking at those; and don't buy cheap. Just buy Mopar.

RwP

 

Turns out it was the crank position sensor... here is my next question. what could be causing this thing to blow these sensors back to back to back to back .... ill drive it for 10 miles and it starts doing it all over again. replace the sensor dirve it a handfull of miles and it starts again. rinse repeat so on and so forth.

 

Think I would start suspecting the ECM, not the sensor......

 

Well, there's four possibilities that I can see.

1) You're not using a Mopar sensor, so it's a crap sensor.

2) It's actually the connection, and replacing the sensor reseats everything for a while.

3) There's one sensor for automatics, another for manuals; maybe you have the wrong one?

4) There's actually a problem with the flex plate / tone ring, and bran'new the sensor manages to work, but it quickly gives up the ghost.

RwP