I’ll give as much detail as I can, any help would be greatly appreciated:
3 days ago I was on my way to get a new tool box for my home shop. I stopped at the first fuel station 2 miles from my home and filled up at the diesel bay, where there is no chance I put in the wrong fuel. I started up and took off, but only made it about 200 yards before it surged for a couple seconds and died. There was no warning and I was completely caught off guard. I checked the mirrors for a puke trail (because it sounded bad when it died) but the road was clean. Everything looked fine under the hood so the next think I did was, turned the ignition back on and kicked the starter to check lift pump pressure. (I have the AirDog set up, and a pressure gauge on my pillar.) The lift pump didn’t turn on. Now, I assume that the lift pump never turned on when I left the fuel station, and I ran the 200 yards with the vp44 sucking what it could, dry.
Next step: get the lift pump running: its supply voltage was fine to the relay, but the computer wasn’t turning it on as it normally did (it plugs in to the stock lift pump harness.) To get it running, I jumped the terminals in the relay connector, thus bypassing the computer. But this is a question to come back to: what would cause the computer to not turn on the lift pump?
I have since bled all 6 injector lines at the head with the hotwired lift pump, and it won’t so much as fire. With minutes of cranking (breaks in between cranks), still nothing.
Error codes:
P0122* Throttle Pos Sens Voltage Low
P1596 Speed Ctrl Switch Always Hi
P1693 DTC Detected in Companion JTEC Mod
I don’t know what to do with the last two, and basically assumed that they are not of significant issue. I followed the Chrysler diagnostics steps for p0122. I confirmed that I have adequate voltage coming from the ECM and that the wiring between the APPS and the ECM is fine. Which then the manual tells me to replace the APPS……The manual never actually tells me to test the apps, but this is what I then did: I checked the no throttle output voltage to the PCM on the firewall. It was .43v. It was supposed to be .54v according to the sticker on the APPS. Low, yes.. dead, no. I loosen its adjusters and rotate the sensor to get the voltage up. I was able to increase it to .49v. Then I move the throttle while reading the output, and the voltage appears to be linearly increasing. So, replace the APPS still? Why? It seems to be working fine, it’s an analog potentiometer… The truck should be able to run, if its providing output near where it’s supposed to, which it is. Correct me if I am being thick skulled, but I think the manual was trying to get me to waste money.
This is about the extent of my story. So here I am with these 2 questions:
Why won’t it start, when fuel comes out of the injector lines, after having bled them all?
And again, what could have caused the computer to not turn on the lift pump? (I still have to jump the relay to get it to turn on)
The one last thing to mention, which is what is so bizarre, is: if the truck failed to turn the lift pump on…yet it kept running until it ran out of fuel (I think), why wont it start after bleeding the lines?
The alternate scenario, is that it surged and died all at once, and THAT is when the lift pump stopped working, not when I refueled. If this is the case, than it never actually ran the vp44 dry, and I think my ECM is shot. (but when I bled the lines, there wasn’t instantly fuel,,,, so I do think the lines were dry)
Any input would be appreciated,
Derek
p.s. I disconnected the edge comp, which did nothing. I should also note that my vp44 as 20,000 miles on it since it was installed (as a refurbished unit) by a dodge dealer.

 

make sure the fuel station you filled at didn't have what they call a cross drop. as we all pull up and expect to get diesel from the diesel pump does not mean some delivery driver could have cross droped which is putting the wrong fuel in the diesel tank meaning they could have filled it with gasoline I hope not

 

Yeah check your fuel. So do you think you'r getting fuel? How old are your batteries? If your batteries are newer then 4-5 years, then test from the tank to the injectors, for fuel flow. If everything checks out then start testing you Computer systems, making sure they have good voltage and they are putting out the right signals.

 

this is a tough one because you have so much going on at once here

if you have addequate fuel pressure and fuel comming out the injector lines it should fire however I have seen this before, its tricky, get yerself someone to help, pull the ruber boot to expose the inlet to the compressor, then get yer buddy to turn it over while you squirt a good lubricating oil like WD-40 in there, trust me if the truck want to run it will do it here.

 

I got it to run and idle by hotwiring the vp44 (pin 6= ground (top, closest to block), pin 7 = 12v bottom, closest to block). I jumped the lift pump relay again and it fired right up. It will idle like this, nothing more, but it will idle. This test confirms that the fuel system is mechanically fine and that the VP44 is not the source of the problem. Its looking like it could be the ECM. The grounds, and 12v+ inputs to the ECM are good, but there is still the potential that some of the other inputs have issues. Someone gave me the list of what to check before i go get a new computer. I'm going to do that on friday when i get home.

But the VP44 trick was really cool... Had i known that on Friday, I would have idled home... (thanks Tim at Timbo APPS)

 

Good thread! Glad you found somebody to help you. To bad it was the ECM.

 

Going to print this and keep it in the truck. Never know!
Thanks.