Diesel

[Diesel2door96]

Hey! New to the forum, I don’t do the social media stuff, but here’s the problem.
I have a 96 2 door diesel with the 6.5
I have been having issues with it after warm up, it’ll run great for about an hour or so, and when on the throttle, but when I am sitting at a light or just idling, it’ll start hesitating like the fuel is being restricted. I’ve since replaced the lift pump, pmd 3 times, injectors, fuel filter, fuel solenoid, I’m not sure what else to look for to remedy this. Thoughts?

 

[OR VietVet]

First: Welcome to the forum.

Second: I am not a diesel mechanic but I can guess with the best. Since you said it runs fine at throttle but falters at idle, I would not think there is a restriction. If there was, it would not run better at throttle. It almost sounds like is too much fuel at idle. I am ASSUMING, there is a way to tee in to a fuel feed line and see what is going on with the pressure when the problem happens. I would also want to know if the compression is good in all cylinders. Afterall, no spark, but compression is what helps with the power in those cylinders. At throttle, a weak cylinder compression could be hidden. I may be way off base but will pat myself on the back if I guessed right. Good luck.

 

[Eman85]

You can check fuel pressure to the pump at the bleed line at the front of the motor. If it's running place the bleed line in a container and open the valve and see what happens. If the motor dies there's a fuel supply issue. Any check engine light or stored codes? While thinking and diagnosing a problem like this I would pull the PCM leaving it hooked up and LIGHTLY tap on it with the handle of a screwdriver with the truck running. I've had vehicles act up and or die when doing this and it's a bad connection or bad PCM. Also with the truck off unplug the PCM and look at the connectors for corrosion.

 

[Diesel2door96]

You can check fuel pressure to the pump at the bleed line at the front of the motor. If it's running place the bleed line in a container and open the valve and see what happens. If the motor dies there's a fuel supply issue. Any check engine light or stored codes? While thinking and diagnosing a problem like this I would pull the PCM leaving it hooked up and LIGHTLY tap on it with the handle of a screwdriver with the truck running. I've had vehicles act up and or die when doing this and it's a bad connection or bad PCM. Also with the truck off unplug the PCM and look at the connectors for corrosion.

The electrical lines to the PCM are good, it was relocated a few years ago, I don’t see corrosion anywhere. When I changed the fuel filter, it did quiet it down quite a bit, but still hesitates. Just not as bad

 

[Diesel2door96]

You can check fuel pressure to the pump at the bleed line at the front of the motor. If it's running place the bleed line in a container and open the valve and see what happens. If the motor dies there's a fuel supply issue. Any check engine light or stored codes? While thinking and diagnosing a problem like this I would pull the PCM leaving it hooked up and LIGHTLY tap on it with the handle of a screwdriver with the truck running. I've had vehicles act up and or die when doing this and it's a bad connection or bad PCM. Also with the truck off unplug the PCM and look at the connectors for

First: Welcome to the forum.

Second: I am not a diesel mechanic but I can guess with the best. Since you said it runs fine at throttle but falters at idle, I would not think there is a restriction. If there was, it would not run better at throttle. It almost sounds like is too much fuel at idle. I am ASSUMING, there is a way to tee in to a fuel feed line and see what is going on with the pressure when the problem happens. I would also want to know if the compression is good in all cylinders. Afterall, no spark, but compression is what helps with the power in those cylinders. At throttle, a weak cylinder compression could be hidden. I may be way off base but will pat myself on the back if I guessed right. Good luck.

thanks.

It runs good when it first starts up as well, it’s only after it warms up. Almost like a weak part on the fuel side, and when it heats up, it’s causing it to falter, but again, it isn’t throwing any codes, just hesitating. I’ll have to check the cylinders when I have a chance. It’s going to a shop so I can have it on their computer and see if they see anything. I’ll update if anything comes up from it

 

[exp500]

Check your EGR valve.

 

[Eman85]

I mean the PCM (powertrain control module) or computer when you use general terms, not the pump mounted driver that was mounted on the pump that you relocated.