99 F-350 PSD.

Recently I have been experiencing an unusual problem with my truck.

The check engine light comes on every once in a while and does not let me accelerate. I checked at Autozone twice with their diagnostic meter and no codes showed up. When this happens the truck will still drive in idle speed, it just won't let me accelerate even if i floor it. I wait for a minute or two and then the light goes off and everything is fine.

This has only happened three times in the last month.

The latest occurence happened when I was going uphill and kicked into third to get the turbo boost. I kicked in and started to boost and then the light came on (and I stopped boosting obviously). It took two minutes to reset. The next morning when I started it up, the light came on again for a few seconds. Very odd.

I am new to these trucks so I hope it's not something simple I am missing.

Thanks for any suggestions you have.

 

I would look at the fuel filter and bowl first, for asimple possible fix.

 

Sounds like the Throttle position sensor is on its way out. But you can't change just the sensor, the whole pedal assy. must be replaced. About $70 from FoMoCo.

 

Thanks for the response.

I checked the throttle position sensor in my manual:

"Diesel engines are not equipped with a throttle position sensor. Idle is detected by the idle validation switch while acceleration is detected by the accelerator position sensor. Both components are mounted on the accelerator pedal."

Here is what it says about the accelerator position sensor...:

"The idle validation switch, the accelerator pedal position sensor and accelerator pedal are replaced as a single unit.

The accelerator pedal position sensor is used to monitor the driver’s demand for power. The idle validation switch and the accelerator pedal position sensor are combined into a single unit. The PCM adjusts the amount of fuel injected into the cylinders according to the position of the pedal. The idle validation switch protects the engine from in-range acceleration problems. A problem in the accelerator pedal position sensor circuit will set a diagnostic trouble code."

1) If it were the fuel filter, wouldn’t it be a more persistent problem?
2) If it were the accelerator pedal position sensor, wouldn’t the autozone diagnostic meter have spotted it (nothing showed up)? I hate to spend $70 on something I might not need.

Thanks again for the responses.

 

Ben,
I believe Hughesm1 is correct. From what I understand the accelerator pedal can develop "dead spots" depending on how it wears. Sometimes it works fine, other times it doesn't. I have a friend who maintains several PSD trucks at a local airport and he has described the symptoms which sound very similar to yours.
At least it's a cheap part........relatively speaking of course.

If you know some one with a PSD equipped truck see if you can swap pedals for a long enough to take a test drive.