I have a 1999 ram 4x4. I had a low mileage motor put in a few months ago. Starter shorted out so I had it replaced, fuel pump went out a few days later, so I had it replaced. Ran great but then started just dying for no reason. No sputtering just died, would lose gauges and get no bus on odometer..... wait a little while and it starts right back up and ran great.......for a couple days. Started backfiring and lost power. Code said crank or cam sensor, so I replaced crank and distributor pickup under cap. Got better but still backfiring and no power. Replace IAC, MAP, ECM, and O2 sensors. It still backfiring out exhaust and no power. There are no cats on it. I am stumped. Please help me figure this out

 

With the crank and cam sensor if it isn't a Mopar sensor change it out to Mopar.

 

I will try that. The man at the parts counter says there is supposed to be a gauge to set the distance on the crank sensor. Is that right?

 

Not that I am aware of.

 

The Mopar crank sensor didn't change anything and it was$112 at the dealership. The backfiring and no power started about 2 days after I changed the crank sensor the first time. It didn't just die anymore. I have changed it 3 times now with a more expensive one each time. It is not giving any codes. Could the shop have accidentally done something when they changed the fuel pump. Any other ideas?

 

Wires for cam or crank sensor pinched anywhere?

PCM for the correct size motor?

Was the distributor pulled out of the motor at all?

 

I don't believe so. It ran great for almost a week after they changed the fuel pump but then it started just dying and losing gauges. I changed the crank sensor because I read a post that it was the problem. It did stop the motor from dying but after about 2 days it started backfiring out exhaust and no power. I can really smell the fuel. I changed the crank sensor again with a better one because it sent the code no communication with crank or cam sensor. No code now but still backfiring and no power. I did get one more code saying lean on bank one.

 

Check the temp sensor on the engine. It's either by the heater outlet hose on the passenger side, or next to the thermostat housing, behind the a/c compressor. Make sure it has a good connection, and the wire isn't shorted out somewhere.

The no bus thing is usually a bad sensor on the 5 volt bus. (which is almost all of them......) These trucks also HATE aftermarket sensors, so, if you still have the old Map, etc, and nothing changed when you changed them, but the originals back on.

Do you have a scanner that can read live data??

 

The motor also keeps fluctuating the rpms. When I changed the sensor it got stronger but the problem is still there. My scanner can tell me some live data but it ain't a fancy one

 

Could the ignition ( or some part of it) be causing this problem? The shop that put the motor, starter and fuel pump in says I need a new ignition...... kinda got a strange feeling when they said that.