why would someone bypass the stock fuel filter? why would you run a direct line from the line pump to the injection pump?

 

did they install a fass or air dog under the bed with its own filters?

 

looks like a fass. i replaced the filter and i still have a problem. still getting the TPS code and it was replaced. it will idile all day, just as soon as i hit the gas pedal it wont react to me pressing on the pedal.. it hesitates... what the?????/

 

problem may lie in the APPS unit, not the fuel pump/filter you can do a reset (unhook the batteries for like 1/2 an hour, rehook them and turn the key in the on position, slowly depress the pedal and slowly let up on it) and there are some fixes by adding a new ground did it on mine and it works but my truck just surged not quite like your symptoms

 

if its the apps, Timbo on hear has a good cheap upgrade

 

Is it possible that the relay is bad?
I will try this tonight when I get home, thanks fellas.

 

Checked for codes? Sounds like the apps. Search apps recalibration to get you by until you get one from timbo, if that's the problem.

 

reset apps, no luck, checked in line relay from Fass unit. no luck. code i get are p0121,0122,1475,1693. is the apps/tps the same? Some codes say voltage too high and some say voltage too low???? any suggestion would be apreciated. truck has been down for more then 2 weeks.

 

have you cleaned the grounds??
just a guess, but many problems are ground related..I know I've had some too.
start at the batteries..then the ones that connect the batteries to the motor and the body..
-dkenny

 

Apps/tps are the same thing. Didn't read that you had installed a new apps until now. I still wouldn't hesitate to use the old apps and try https://www.dieseltruckresource.com/...n&onlynewfaq=1
and cleaning the ground is also a good suggestion.