Just put a good used pump on this 99 24 valve and it runs great for a while then it looses all of its power like it is going bad, New lift pump good fuel pressure 13 wot power max 3 competition box doesnt matter if box is on or off or all unhooked.. It would not go over 35 mph in 3rd gear wide open then all of the sudden it just takes off, Whats the deal anybody know... BOSCH NEEDS THESE PUMPS PUT WHERE THE SUN DONT SHINE ON MOST OF US...

 

Might not be the pump, but the APPS sensor...

I've now seen trucks throw "bad pump" codes when it was just the APPS sensor.

What I did was monitor the APPS voltage using the OBD2 software (it's almost as easy to do it with a regular, digital voltmeter) and could see it was putting out nonlinear voltage...

see if your APPS is putting out sensible voltage, or if it's wandering all over the place. If it sends too crazy of voltage signals to the pump, the computer will think the pump's bad. I am believing a LOT of VP44s have been replaced for no reason... a number of them have come in off dodge trucks to a local Diesel shop that rebuilds them, and they were all perfectly fine...

 

I'm curious about this comment. I've replaced alot of pumps over the years, most p0216 related, some not, and I've never had a comeback that ended up being an APPS. As matter of fact I've only replaced probably three APPS sensors in the last six years. Just an observation.

 

If you were to mistakingly replace a VP when the APPS was the only problem wouldn't the problem still persist w/ the new VP due to the signal from the APPS? just a thought

 

I asked my friend that works for the local diesel engine shop, and he says that in 1 year of working on that series of bosch pumps, he's seen 5 or 6 come in for rebuild that were not malfunctioning... not all have been from dodge trucks, nor did he specifically say it was an APPS-only problem (that part was MY speculation)...

 

I hate to ask a stupid question but here goes "What is an APPS sensor..." Sorry I am knew to this game.

 

Doeracing WELCOME to this great site. For a list of abbreviations you can go here: https://www.dieseltruckresource.com/...n&onlynewfaq=1
Tom

 

I was just thinking it was that too if you let all the way off the pedal to an idle it will pick right back up again how do you check too see if that is the problem?????

 

MnTom thanks I have a 99 doing the same thing and took it to what I thought a knowlegable dealer on diesels buti cant see where he even put it on the computer. The service manager said being the age and miles (125,000) that it was the injector pump seen an old service manager for our dodge dealer and descibe the what was happenning and he said he thought It was the APPS too know that I know what that means. Thanks again.

 

You have to monitor, in realtime, what the APPS (accellerator pedal position sensor) voltage output is doing.

Treat it just like a Throttle Position Sensor on a gas EFI motor. It converts the accellerator position into a varying voltage (low to high) depending on pedal position. Make sure the voltage smoothly increases as you press on the accellerator - a dirty or contaminated APPS voltage signal will wander all over the place...

 

Hey Dieselgeek...interesting comment about the APPS. My truck sits in front of the house...DOA after a 2,000 mile run from Oregon with a known APPS problem...and we were thinking the pump had died (see thread in Help,"Cranks but won't start"). I know where the wires come out for the APPS...could you please detail which ones to hook up a digital volt meter too? And will this work with the key on, engine not running? (since mine won't start). Thanks for the help! George

 

Underneath the black plastic cover, at the end of the shaft the throttle cable and cruise control cable are attached to, is the sensor. it has three wires going to it... I forget the color combinations, but if you use a VOM you'll see one is getting constant (I think 5v), another is ground (no voltage) and the third is the variable voltage output. I stuck a needle into this third wire and attached the VOM positive lead to it... this works with the key on. Make sure you didn't blow an ECM fuse or something simple like that...

Good luck, keep us posted. If you need, I'll go look at the truck tonight when I'm home and give you better details...

 

Thanks, Dieselgeek! Mine has six wires, but now I understand the principle and can figure it out, I'm sure. Really appreciate the help! (And thanks to a great website!)