Hello all, great site and great info...here is my problem...
Failed vp44 2 years ago, replaced and added FASS fuel system, has run flawlessly since. I had my Fass filters changed by the same mechanics who did the install before a roadtrip for thanksgiving- about 35,000 miles on filters-after new filter install i began having issues, in this order...
1. Sitting in traffic, low rpm, accelerate and engine dies. Restart and initially have little to no power (dead pedal) then accelerates and no problem.
2.Next day, driving at about 65mph (2000rpm) then jumps to 3500rpms with no acceleration, let off gas, resumes to normal and no problem.
3.On my trip home i experienced similar random jumps in rpm (dead pedal) but also drove for a good 3 hours straight with no problems.

Any ideas? I'm a carpenter, not a mechanic so please excuse my lack of knowledge. I have noticed that my battery terminals are not the cleanest- if my Fass connection on the electrical end is suspect, could this contribute to the Fass pump missing a beat? How do you diagnose the mapsensor... any info at all would be appreciated!

98.5 24 valve
211,000 miles
no gauges
lots of tlc

 

Do you know anyone that has a code reader? It's sounds like your APPS is going out. Do a search there's plenty to read on the subject. You can try to reset the APPS, not sure if it will do any good but worth a try.

 

By the way I'm not a mechanic either but I don't let that stop me from working on my truck.

 

thanks for the advice Mike D, i'm checking for codes tomorrow, though they probably won't show unless i can duplicate the problem while being scanned...just curious if anyone experienced similiar symptoms...
a new APPS might be cheaper than a 5 hour roundtrip to a diesel mechanic to run diagnostics

 

If it was a hard fault it will show with a scanner, you dont have to duplicate problems to get a fault code. That being said there may be no codes in the ECM and it will be a little harder to diagnois. Stock lift pump or fass you still need a gauge or at the minimum a low pressure warning lite, as its the best warning tool you can have, it could be a fuel pressure issue

...and yes you really should remove and clean your battery terminals and connections. just remember to remove BOTH grounds FIRST, then remove the Positive. when reassembling install BOTH positive FIRST then instal the grounds last. by doing it this way there is NO chance of shorting batterys/terminals or the wrench in your hands

read this link to help understand how to diagnois your VP
http://www.bluechipdiesel.com/vp44diagnostichelp.html

as per the BlueChip link a bad APPS will set a code, The dealer price ranges in the 300-500$ If you need one do a search for Timbo he has a replacement with instructions that is more robust than the orginal in the 150$ range

 

His user name is timbo01 and it is $160 shipped to your door

 

code 1693 showed up with a "snap-on" scanner, truck ran well today, guess i'll wait for it to happen again and see if i can narrow down the symptom... putting in a call to blue chip diesel to see if a map sensor enema might help and/or pick there brain to find info on non fuel system issues pertaining to the 1693 PCM code.
might go with the "timbo apps" anyway, cause it sounds like a quality upgrade.
thanks for the input nickg and dennis !!