95 Powerstroke surging on startup.
 

Ok my buddy has a 95 f350 powerstroke. As soon as it fires over it comes to an idle, but within a second or two it starts hopping like its getting quick surges of fuel and cutting out inbetween the surges. It eventually evens out after about 10 seconds.

I've done a new fuel filter, oil's been changed and its at the correct level.

I was wondering if maybe it would have to do with a check valve in the high pressure oil pump or something? :humm:

What's the temperature where your at? Is it only on the first start up or does it do the same thing throughout the day?

its the same no matter what temp it is, even right after you shut it off when its hot. i thought maybe it would be a check valve in the oil pump thats letting oil pressure seep back so its not primed when you start it.

Please update. :pca1:

Ok i have replaced the CAM sensor becuase the idiot light came on for that and it was stalling out, so that problem's fixed. But its still bucking on startup. While i had the scantool on it i read pressures from the HPOP (high press. oil pump) and it ranged from about 900 to 4000 during regular driving, TP sensor was right on the money on datastream and with voltages. I checked the fuel filter again and that was all good, same with oil. Also has new injector harness done professionally about 5 months ago but the problem was there before the harness was replaced.

The glow plugs are shot, but i have replaced the relay. and i think we can rule out the gp's because it still bucks on startup if you shut it off after its been running at temp

Have you looked at your ebp valve. If that's acting up, it could cause this.

Updates??

Please update.

thats the vacuum operated valve on the turbo right?? so if i undo the vacuum line the valve should stay closed and eliminate the problem?

No, it is the oil pressure operated valve on the bottom of the turbo. If you look at just the right angle from the top down you can see the wire that plugs in to it on the bottom of the turbo that activates it.