Truck will not start without depressing accelerator pedal?

[frank1]

Having problems with one of my 03"s. Truck would turn over and over and not start (feels like no fuel getting to injector pump). For the heck of it I depressed the accelerator pedal to the floor and the truck fires right up! Happened to me twice yesterday. Started up fine in the morning, happened hours later durning the day. Truck history: automatic, in - tank fuel pump,original injectors, 154,000 miles. Pump, injectors? Never experienced anything like this with any of my trucks, just turned the key, waited for pigtail to go off, turned key and engine would fire right up! Any help where to begin to look would be helpful (fuel filter replaced about 5,000 miles ago- Baldwin). Thanks, Frank

 

[cerberusiam]

Might be time for anew APPS, that is the only thing happening when you depress the accelerator.

 

[frank1]

Thanks Cerberusiam, can I check the APPS with an OHM meter before ordering a new one? The reason I ask is I have no codes shown. Truck also started up fine all day.
Thanks again, Frank

 

[cerberusiam]

You can check the voltage at rest but if it is intermittent you might not find it. Might be time for a Timbo APPS out of self preservation.

 

[Crunch]

Thanks Cerberusiam, can I check the APPS with an OHM meter before ordering a new one? The reason I ask is I have no codes shown. Truck also started up fine all day.
Thanks again, Frank

I've replaced the APPS twice in 13 years, or more specifically, had the dealer do it. There is some way to calibrate it that I am not familiar with so I didn't try it. You have to replace the entire bell housing, too and not just the sensor. If the APPS is the problem you should see a P212x code, depending on what is going on.

 

[cerberusiam]

I've replaced the APPS twice in 13 years, or more specifically, had the dealer do it. There is some way to calibrate it that I am not familiar with so I didn't try it. You have to replace the entire bell housing, too and not just the sensor. If the APPS is the problem you should see a P212x code, depending on what is going on.

Nope, not always. The APPS is not validating position at rest only comparing readings off idle, they go into standby mode at idle and on starting it is not even validating the position.

 

[Crunch]

Nope, not always. The APPS is not validating position at rest only comparing readings off idle, they go into standby mode at idle and on starting it is not even validating the position.

All the problems I've had with my APPS have been both intermittent and only when my truck is already running. They have tended to manifest when I accelerate from a slow speed or after stopping at a light or stop sign. I've never had it affect starting the engine.

 

[cerberusiam]

Yep, that is the normal failure but 03's are lacking on their APPS programming, not very sophisticated.The ONLY thing that changed when pressing the pedal is the apps position and the truck started. It is possible that the min setting has drifted also and mashing tweaked the bell crank enough to change things. It is hard to tell if it is an electrical or mechanical issue so replacing the APPS is the first step if it is old and questionable.

 

[frank1]

Quick update- truck would not turn over this morning and not start,pressed pedal to floor and truck fired right up! Drove down to first traffic light (1.5 miles from house) and truck just shut off!!! Try starting it, no go! Pressed pedal to floor several times- no luck!!! Had to have truck towed!!! Service station is closed on Saturday's, I was to angry and frogot to check for codes! Very frustrating, I depend on these trucks to make a living, thank god it didn't happen during a snow storm, when I really need for them to run at 100%! Cerberusiam, where do I get a Timbo APPS (if it turns out that I need one)?
Thanks again, and I will keep you guys updated.
Frank

 

[cerberusiam]

Now it is sounding like FCA might be giving up.

 

[Tractorat]

I have no credentials here. But recently my truck was doing the same thing. Finally turned out the fuel system was sucking air. Replaced the pickup in the tank (had an under tank sump installed) and the problem went away.

 

[frank1]

Quick update- Got the truck back from the mechanic now for two days. Seems to be running fine, do not need to push accelator to floor to start and so far no shut downs (150 miles since I got it back)! No codes and the only thing he found was the relay that was powering the in-tank fuel pump was possibly bad??? He was under the hood trying to figure out why no fuel was being pumped into the fuel filter housing, he found the in- line 10 amp fuse and 15 amp relay that feeds the pump. Checked the fuse- okay, unpluged and pluged back the relay and fuel began filling up the canister!!! He replaced the relay and so far so good!The dealer had replaced the side mounted fuel pump with an in tank pump when it had failed about ten years ago. The mechanic said to keep on running the truck and if does shut down again, we will need to replace the entire wiring harness that feeds the pump. As far as needing to push the accelrator to the floor to start? Cannot explain? Again, as of today she's running just fine!
Thanks again for all your help! Frank.