Yep. Can't find anything out of the ordinary

 

loose feed tube nuts can cause it to run funny, but i dont know if they will cause a truck to run as bad as yours is. either way it doesnt hurt to retorque them.

 

Is the lift pump indeed working?

Does it physically build pressure?

 

Ok. It's been identified. The PCM is bad. It's only giving intermittent power to the 1, 2, & 3 injectors. I'm going to order a remanufactured PCM from O'Reilly's and put it in. Dealer wants $1,000 so heck with them...

 

^^ This is a terrible post in a technical thread...



1. How did you or someone determine the PCM was bad?

2. What is the low side (lift pump) fuel pressure?

3. What is the high side (rail) fuel pressure?

4. What DTC's are being set and logged?

 

Sorry, I'm not as mechanically savvy as you guys, so it's kinda hard for me. This got over my head so I called in some help from a friend, who is a mechanic and knows his stuff...Here is what we found:

Code P2146 - Fuel inj group 1 supply voltage circuit open
Code P0203 - Fuel inj 3 circuit open

We (mostly him) did a bunch of diagnostics from there checking circuits, and eliminating possibilities. discovered my #1,2, and 3 injectors were not working at all. Assumed it's unlikely I would lose all 3 injectors at once, combined with the circuit issue described by the codes...and the first 3 injectors are wired from the same wiring harness (this part is me talking) separate from the second three injectors that have their own wiring harness. We got it isolated to the wiring coming out of the PCM. He checked the PCM and found to first three injectors it was only intermittently sending any power to them. Unlike the second three which were getting constant power. You could hook his meter onto the wiring coming out of the PCM and see that it was supplying no power, except every few seconds the engine would surge and run normal momentarily, and during that time the PCM was putting out the normal amount of power.

So, the PCM seems to be the problem. Changing it out is within the my skill set and I will do that. If you have any other questions I'll try to answer them, but like I said, I'm no mechanic and some of this gets over my head.

 

Sounds very reasonable and well traced out.

It is rather unusual for a ECM to do that, but hey, someone else has my luck!

If we can help further, let us know, BTW, keep that friend full of beer, his kind of help is hard to find........

 

P2146 is a failed injector solenoid usually, sometimes and injector harness failure either way, when this happens it will shut down that bank of injectors.

I've had this failure twice.

Ohm the injector with a quality Ohm meter with the wires disconnected, it should read less than 2 ohms, if it does then ohm the harness. The computer tries to balance the engine and it will intermittently send power to fire those injectors.

Again...I've had this failure TWICE.

Lastly, be very careful threading the nuts/wires back onto the injector anything more than a few "INCH LBS" will snap the terminal off.

 

Steel you are right. Sorry about the delay between posts, I've been real busy with other stuff and haven't been able to really work on this.

My buddy wanted to do the test your are referring to that day, but my multimeter mysteriously vanished so weren't able to. Tested it today and the #3 injector fails, all the rest are fine. So it seems we need to replace that injector??? After that we can re-check and make sure the computer is working as it should or not, and go from there.

Is that what you did?

 

first time I replaced the injector the 2nd time i ordered and replaced only the solenoid.

 

Steel you were right. Replaced the #3 injector tonight, got everything all buttoned back up and it runs like a top. Computer seems to be working just fine now. Thanks for the heads up. Why the heck did I lose an injector at 82,000 miles????

 

put some better fuel filtration on your truck to help the injectors last longer

 

I've had 4 fail in 120K, two were cracked bodies due to pressure box, which is no longer on the truck, the others were solenoid failure.