I parked my van ('99 ram with 3.9) for a couple of minutes, then went to start it, ran extremely rough for maybe 10 seconds, then died. Cranking after that produced no firing at all. It was running fine up to that point. I've checked fuel pressure, (has pressure, don't know if it's at spec ) has spark, has not thrown timing chain, and appears to still be at correct timing. No issue with air flow. In other words, a vehicle from a few decades back would be running now. Going to check current to injectors next, though I already sprayed starting fluid down the throttle body to no effect. Ideas on where to go from here?

 

asd,fuel pump relay or ecu

 

Then you can rule out a fuel problem and focus on the ignition. A spark doesn't mean a good spark. Did you test for spark at the coil or at the end of one of the spark plug wires?

An orange spark is weak, you want a blue spark. Since you have spark I figure PCM, crank sensor, etc. are good. I suspect you have a weak ignition coil or something happened to the cap or rotor.

 

Cap and rotor are good, I have spark through the plug wires. But it could be weak. To confuse the issue, I pulled a p1391 code from the PCM (intermittent loss of CMP or CKP) however, I shouldn't be getting any spark if the crank sensor is bad, and though I only have a digital multimeter, I appear to be getting pulses to the injectors, which means cam sensor is working. Know of any other conditions that would cause that code to show up? Coil is old, so I'm going to replace it, but that code bugs me.

 

you will be surprised how much changing the iginition coil helps

 

Okay, after going through and replacing most of the ignition system, I now have good reason to suspect flooding as the culprit. If I pull the fuel pump relay and spray starting fluid, I get it to fire up for a couple of seconds. Anyone know the most efficient way to diagnose the cause, or can direct me to a post with a troubleshooting procedure?

 

Did you replace the crank position sensor or test it? Just because you get some spark does not mean the sensor is good.

The same applies to a bad coil.


Jason

 

Okay, turns out I'm a dumbass. Took a closer look at the timing, and though it didn't throw the chain, it had skipped by one tooth on the cam gear. Pulled the cover and found that the chain was stretched. Too hasty with my initial check, I had to get right above the distributor to see that the rotor position was off. At least it was only one tooth, so I didn't lose the top half of my motor.