Engine/Transmission (1994 - 1998) 96 12 valve boost problem

[DiezelDriver]

Truck runs fine to 10 psi boost then lays down runs real rough and puts out black smoke. Has 4000 rpm gov. spring, 60 cm/sq compressor in turbo. Fuel plate removed. 4" exhaust turbo back. Checked intercooler boots, not dumping boost there. This combo has made 40+ lb of boost, no changes made.

 

[fest3er]

Almost sounds like the AFC is limiting fuel until 10PSI, then it opens up and it's suddenly overfueling.

 

[Missouri Mule]

Sounds like a boost leak to me. Have you checked the boot on passenger side for tears/holes(the a/c tubing is close to it)? Also the stock intercoolers tend to leak.

 

[DiezelDriver]

I had all the boots off yesterday all in good shape.
I'll run it today and take notes so I can post better symptoms.

 

[Joseph Donnelly]

The turbo shaft could be out of balance from changing the wheel. Check the compressor housing for evidence that the wheel is rubbing the housing and "stalling" the turbo. Also check the boost line going from the head to the afc housing on the pump governor for leaking, and the diaphragm inside the afc.