First time poster, appreciate all the info exchanged here.

2001 2500 ETH (six speed) 245HP (I have owned the truck since new - June of 2000)

I think the current (subject) VP was installed by me around 2003??? and is the second replacement pump on this engine.

I have always changed fuel filters and  "check" lift pump pressure with a mechanical gauge which is anywhere from 6 PSI WOT to 12-14 PSI (25 second no start check).  I have a FASS DDRP installed (2011), (new overflow valve and fuel drain valve installed recently.

So......I am here looking for a little help

I have had an intermittent dead pedal about one year now.....It has progressively gotten worse over time (more frequent).  About two months ago I had a first time extended crank start maybe 4-5 second delay.  Unusual part about this new issue was that it would only have the delayed start in my driveway on a slight up incline.  If I turned the truck around (inclined down) it started normal (immediately) and when it was on level ground it also started normally.  I continued to drive the truck and decided to replace the fuel filter and check the pressure.....all seemed normal so I did some reading and decided to change the overflow valve and gaskets and tighten the fuel return banjo on the back of the head.  All seemed good for a few weeks and my "incline" delayed start issue was gone also.  Few more weeks later I started it one morning and it immediately started but oscillated up and down in RPM for a say 10 seconds.  Drove the truck and power was really low and dead pedal would come and go as well as now the engine sounds like its "detonating" engine sounds like a bucket of bolts.  Engine has a totally different (louder) engine noise than normal.  Did some more reading and I have been driving around with a clear hose under my wipers and my mechanical fuel pressure gauge for three weeks now.  No air in the system and FP is normal.   I even ran new hoses from the bed to the transfer pump and back to 5 gal of fresh diesel in a can and no change.  Also thought I may have a bad batch of fuel so I drained the tank and refilled with fresh good fuel and again....no change.

The only code it has ever thrown is P0122 APPS.  I did the "blue chip" APPS troubleshooting and I am fairly confident its not the APPS.  I am starting to believe it is either fuel valve solenoid (between the six distribution valves) or the advance solenoid or the computer (PSG) on top of the VP. I want to believe its the fueling solenoid as I have no timing codes set. But if the PSG commands XX fuel and correspondingly fires the fueling solenoid I don't think its getting any feedback as I don't think it measures flow?

The questions I have are:

1. Can the PSG (computer), Fueling solenoid and advance solenoid be individually tested? 

2. If the PSG is bad I already know if it gets replaced the pump has to be calibrated on a Bosch EP815 test stand.

3. If I can find and replace either solenoid will I get away without needing calibration?

4. Could it be the timing piston or another mechanical issue inside like a clogged mini screen?

This is driving me nuts as I like many, can't stand paying $1,250 for an exchange VP44

Any help or suggestions will be appreciated.

Thanks in advance, Leo

 

I ran a 2 pump set up many years ago on mine. I had the in tank like you and a booster pump mounted to the frame rail. I cut it into the oe fuel lines and used hose and clamps for that. I never had any issues with those connections. Ran that set up for 4 years or so. It is not the best setup by any means but it worked.

I just resolved (I hope at least) this same problem. It was one of three things, the tune from a smarty I had loaded, banjo on back of the head SLIGHTLY loose (but didn't feel wet or anything), or my fuel pressure gauge (either fitting or gauge itself) was leaking air.