'96 runs rough at RPM over 2250
 

I have a '96 PSD that runs like it dropped a couple cylinders anytime the RPM gets up to about 2250. It seems to run smoothly until this point although it doesn't seem to have nearly the power it once had. The problem is really bad if I try to pass someone starting about 50 mph in 4th gear. By the time I get to 60 it's so rough that I have to let off the throttle. It's a steady and very regular miss. I let off the throttle and once it slows a little then it's smooth again. Any ideas?

Any ideas on this?
Chuck

Yes, clean the fuel pressure regulator screen.

But first, check your fuel pressure with a tire gauge on the side of the fuel bowl with it idling. Stock should be about 50-55psi.

To clean the screen....
Drain the fuel bowl
Remove lid and filter

Use a flashlight and mirror to look into the small hole inside the bowl twards the top on the drivers side. You should see a shiney screen. If not, use a qtip stick (no cotton) or something similar to brush the crud off until it's clean. You can use anything you want, you just don't want to damage the screen. Some sort of soft stick works best.

Reinstall filter and lid. Fire it up, let it idle for a while. Then check fuel psi again.

I cleaned it before checking the pressure. It was pretty dirty. I got 55# afterward and it seems to have more power.
The running rough is actually a vibration and is related only to engine RPM whether or not I'm on the throttle and whether it's clutched or not.
I've heard some things about a dual mass clutch/flywheel. Mine makes a growling noise at idle but it goes away with light clutch pressure. Could that have something to do with the vibration?

Absolutely. Does it rattle when you turn the truck off?

This isn't a good time for me to be replacing a clutch and it's been doing it for a good while. I guess it won't hurt to keep driving it as long as I keep the RPM down. This isn't a good time for me to replace a clutch. How difficult is it to do the job? I have a big transmission jack.

I saw your old posts about clutches. What type do you recommen?

Changing the clutch out is not that big a deal if you have extra hands. It's just everything is heavy. But the tranny jack will help alot. Check out www.valairinc dot com and go to the performance section. And check their clutches out. If you see one you like, you can call and talk to Dan or Kevin and tell them Cody from Death Row Diesel sent you and they will knock quite a bit off the price listed. But their clutches require a single mass flywheel. I'm certain nobody can beat their price on a package deal, especially if you tell them I sent you.

With the vibration like it is, it's not good. In the big scope of things, if it lets go completly, it will trash the tranny and or motor......possibly. Worst case it flies through the floor. Not trying to scare you, but it can happen. I highly doubt it will, but can.

Call Dan or Kevin, we posted over each other. They will talk you though exactly what you need. I'll get back to you, I gotta get off line for a while.