Hi there everyone. I'm in need of help desparately!!!!! I have a 92 ram with a 318 magnum. Quite some time ago it jumped time. I got it all tore apart and it was lined up, however there was escessive slack in the chain so I replaced it all. Got it all back together and it fired right up. The motor ran great until you put it in drive and took off, nice and smoth all the way up to the rev limiter when in park, but rins like crap in drive when under load. It was like it was running on 4 cylinders. It never did this before. All I did was replace the timing set. Well then while driving it around the neighborhood it went POP BANG POP and stopped dead in it's tracks, just like it did when it died before when I replaced the timing set. I got it back home and checked the timing and it's fine. I turned the ignition on and cranked it with a remote while having a timing light hooked up. No light. So I check to see if the coil is getting power and it's not. Power comes from the injector wiring and gets it's ground signal from the computer. The injectors are getting power but still nothing with the coil. So I figure its the computer. Yay, maybe a new computer will also help with my key problems too I thought (alot of times the truck will not shut off using the key, I have to pull the coil wire, it will start every time though). So I got another computer and still nothing. what in the world could this be. Please Help!!!!

 

Crank Sensor? Maybe. Coil actually gets it signal to fire from there, i think.

 

If you haven't found it yet, fix the switch first to be sure, then chk the ASD relay/wiring between the motor and the ASD relay. ASD feeds the fuel pump and coil. Also look for a bad ground to the computer. A bad ground could unlatch the relay and/or the neg side of the injectors. The computer grounds the injectors/ASD internally,but it's gotta have a grnd circuit.
Hook a test light to the + coil and turn on the key,see if you momentarily get a light,also while cranking with the key.If not hook a 12v jumper to the coil +. If it runs,the crank signal is OK. If not chk for crank signal with a multimeter.All things considered, and all injector + are hot, the running on 4 sounds likeeither abad coil, ground, wiring,or a crank signal problem.A few things to chk. Hard to say without being hands on.
By the way,pulling the coil wire can send 30-40,000 thousand volts to the neg side of the coil circuit if you don't ground the coil wire. It can also fry the coil. It's gonna go somewhere. Not good. You did chk the coil wire itself didn't you?