Hi Folks, looking for some help here on my Durango. Here is the story:

Driving at 70mph on the interstate with no history of problems.
Suddenly, no power, vehicle apparently just died.
Truck will not re-start. Cranks powerfully but does not start.
Towed to dealer, who charged 4 hours of labor and diagnosed as PCM.
I did not want to pay their quote of 900 parts&labor, so I ordered my own.
Replaced PCM- no big deal- but, also no change: still cranks but no start.
Current tested good at fuel pump, fuel pump relay tests good.
Fuel pump runs when power is applied directly.
There is pressure at the release valve on the fuel rail.
There is spark at the cylinders.

I don't want to pay the dealer another $350 to misdiagnose the problem again. Has anyone had a similar experience, or does anyone have suggestions?

Thanks so much,
Chris

 

Did you have the PCM flashed with your VIN?

 

Green is right!

The PCM needs to be flashed by the dealer before it will start.

 

The PCM was ordered from ACE in Florida, a remanufactured unit. They already flashed the PCM with VIN and mileage prior to shipping. Auto Computer Exchange has gotten pretty positive feedback in the forums, so I'm assuming the PCM is not the problem any more.

My thought is that the PCM must be looking at some other sensor before supplying ground to the fuel pump. That "other" sensor is not providing positive feedback to the PCM, so it's not supplying ground, keeping the fuel pump from turning on. My problem is, what is that sensor?? Crank position or cam position sensor don't seem to make sense as there is spark at the cylinders. Something else I'm missing?

HELP, please....

 

The fuel pump only runs for a couple seconds at key on, if you start cranking the starter the pump comes back on during cranking. You should be able to hear the pump. Some are quieter than others so you might have to listen with the filler cap off the tank while someone turns the key on. The cam sensor, you should be able to see with an analog volt meter, it will go up and down like a turn signal, it only goes positive to 5 VDC and back to 0 volts once per revolution. The crank position sensor has 8 pulses per revolution so I doubt you can see it with an analog voltmeter, I use an oscilloscope, again +5 VDC to 0 VDC. You would also need an oscilloscope for the pulses to the negative side of the coil, 12 VDC, but if you put a timing light on a spark plug wire you will see the high voltage result of those pulses.
If you are working alone you can hook a wire to one of the terminals of the start relay in the power distribution box. Just closes a relay so you can crank the engine using low current, touch the wire to the positive post of the battery. You need to check the Automatic Shutdown Relay. I believe it shuts down the supply voltage to several things. Usually there is another relay you can swap it with, same relay, same part number. I believe there is also a fuse for the ASD relay, if that is blown you aren't starting. That relay can probably cut the 12 volt supply to the fuel pump. Do you have a fuel gauge to hook up to the fuel rail? Mine didn't seem like much pressure when I released the valve with my finger but the pressure is good.
Check for 12 VDC at the fuel injectors. The other injector wire will also be at 12VDC until the PCM sends it a 0 volt pulse, turning the injector on for an instant. Either need a scope or one of those special lights to see that. If you've been cranking this and the plugs aren't wet, the pulse isn't going to the injectors. The PCM has a seperate ouput for each wire to each injector.
You can check the supplies to the crank and cam sensors easily. 5VDC on the two outside wires of the connectors, the middle wire is the signal.

 

As midniterider was saying the cam and crank position sensors should be checked out first. I doubt it is an injector issue as you aren't getting any cylinders firing but I could be wrong. It looks like he has a good grasp of troubleshooting. You definitely need to make sure you are getting spark at the right time or you'll be going nowhere. How long has it been since you timed the engine? This should be done every 60K miles.

 

How do you set the timming on our engine??? I thought it was done by the PCM

 

I did some researching on it and you're right. That hurt.

 

It's ok I drink to before I get on the forum. It makes things alot more funny