No start

[Franklin]

Do these immediately come back when cleared? These are a symptom of other problems as I feel your tank leak is more important to fix first (AIR) for the no-start condition.

DTC 22 - Accelerator Pedal Position 1 Circuit Low
DTC 25 - Accelerator Pedal Position 2 Circuit High
DTC 63 - Accelerator Pedal Position 3 Circuit High

This has grounds, that you cleaned up, or positive battery cables needing attention. Otherwise you are looking at the accelerator pedal position sensor needing replaced or ECM needing replaced. Wiring is a very real possibility with the age of our trucks. The way to verify what is going on is checking voltages and or using the http://leroydiesel.com/products/gmtd-scan-tool-software/ GMTD SCAN TOOL SOFTWARE.

You won't see a "noisy" worn out sensor tripping the ECM with a voltmeter, but, it will eliminate shorts and open wires/sensor.



Did the return line fill up with fuel? Do you have fuel flow at the water drain when you jump the lift pump "on"?

Any air leaks, even on the return side, will allow air to enter the system that needs to be purged out. This purging results in long crank times or no start conditions. Note 30 seconds then wait 2 min for the starter to cool. Otherwise it starts to melt down.

It's known for the pickup assembly on top of the tank to rust out giving you a pinhole on the lines. The fuel leak means a massive air leak. It could be on the return side, but, if it's the suction side you may not be getting fuel at all. The tank needs to be dropped, or bed removed, to figure out why there is a fuel leak. Hint: drain as much fuel out of the tank as you can before dropping the tank.

You can try to feed the lift pump from a 5 gal can of diesel bypassing the tank to see if that helps. This will narrow down the problem areas.

I'm getting fuel to the pump. I'm not seeing any air in the return line..

 

[WarWagon]

At this point I suggest running the section 2 electrical tests flowchart in this PDF attached here for your ease of use.

I am really not getting a clear picture from unanswered questions so I am guessing in the dark.