Hi guys. I'm relatively new to this website, so bare with me while I stumble through this. Whenever I do post here, I always get info that is right on! I have a 98 24 valve CTD with 148K on it, manual transmission, no previous issues. In the last month I noticed an occasional flat throttle response. I saw it was time to change the fuel filter, so did so. I saw when removing the previous filter that the retaining nut on the fuel filter canister was loose, and thought that maybe I had been drawing air. Shortly after replacing the filter, the truck started the same issue, and is doing it quite frequently now. When cruising at steady throttle for a short time, there is no throttle response when throttle is increased. If I push in the clutch, the engine will eventually raise to a higher RPM. If the engine idles between gear changes, the throttle acts normal for awhile. I don't see a check engine light. Will this normally throw a trouble code that won't activate the check engine light? Any ideas or tips? Thanks for your input.
rjrkihap steered me in the direction of Blue Chip diesel and they seem to have alot of knowledge pertaining to our pumps. Here is their website:
Blue Chip Diesel Performance Specialists
Here is what they say about a dead pedal found in the VP44 DIAGNOSTIC HELP TAP
DEAD PEDAL
This is THE MOST COMMON DRIVABILITY COMPLAINT and is an intermittent one that usually happens when the truck is hot or working harder, such as towing or on a hotter day, but can occur when cold too. This symptom is rarely caused by a faulty APPS (Accelerator Pedal Position Sensor) and 99% of the time is a faulty computer on the top of VP44 injection pump. The best way to positively eliminate the APPS as the cause of the problem is to read the DTC codes in your truck to check for any pertaining to the APPS, such as code 121 or 122. If there are no DTC codes pertaining to the APPS you DON'T need an APPS. A bad APPS, always, in my experience, sets a code even if it misbehaves for just a second, so if there IS a pertinent DTC code, replace the APPS. A possible pitfall here is if someone turned the key on when the APPS plug was disconnected. This will set an APPS code, so if you think this could have happened, clear all the codes with a scanner, recheck for codes to be sure all codes were cleared, then drive the truck until the drivability issue occurs and see if the APPS code returns. If it does, replace the APPS. Even though you replace the APPS it may not solve ALL your drivability issues, because you may also have injection pump problems.
If you don't have access to a scan tool, or can't read the codes as explained in above paragraph about codes, and want to trust my experience, let me explain the difference in symptoms between a bad APPS and a bad computer on the injection pump. A bad APPS usually is just a flat spot at a certain throttle opening, usually 65-70 MPH, and smacking the pedal to the floor a few times, usually clears it up. If pushing the throttle just a bit more makes it take off, or if going back to a lesser throttle opening makes the engine run fine, then it is a bad APPS. This usually occurs most frequently, but not always, in cold and or wet conditions. I would say that the APPS is the culprit maybe one time out of 100 times, so replacing it without an accurate diagnosis is a waste of money and time. We now offer a reasonably priced APPS! Call for details.
If it is caused by the computer on the VP44, the "Dead Pedal" occurs at ALL throttle positions and will only reset and play again if you just wait, let the pedal go to idle for a brief time, or push the clutch in, or shut off and restart the engine. The "Dead Pedal" happens most often when hot or towing, but sometimes occurs shortly after start up when cold. There are no codes pertaining to "Dead Pedal" that will condemn the computer and therefore the VP44. If the truck has a proven good APPS, and has an intermittent "Dead Pedal" and no codes other than a 216 and or a 1693, YOU NEED AN INJECTION PUMP! It really is this simple.
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