Rough running, turbo on/off

[KenDavis]

Opinion Please. Usually my 94 Suburban runs at 500-600 degrees while cruising normally and boost reads 5-7 lbs. Several times now I've seen the exhaust gas at 800-900 degrees and turbo boost at 0 lbs. If it stays too long in this condition it will start to run very rough and at idle. Dealer wants to replace the IP and fuel lift pump, $2300. I took it home. Another repair shop I talked with over the phone stated that it sounded like the fuel lift pump acting up, rough running due to not getting enough fuel. OPS was changed 1000 miles ago which got the fuel lift pump working again. Maybe it was bad to start with. Question is: would the fuel lift pump cause the turbo to not work at times? Or am I looking for something else? Help.

[Robyn]

Are you getting any codes?? (check engine light coming on)
Could be the vacume pump or the waste gate solenoid. ( little device on left valve cover toward the rear with 2 vacume lines going to it.
also the waste gate solenoid gate take a poop too.
Make sure you have vacume to the waste gate pod with the engine running.
If not check for vacume at the solenoid ( orange plastic line)
If you have vacume to the solenoid and the waste gate has non its probably the solenoid. They are about $35 and take a couple minutes to change.
The manifold absolute sensor can cause issues but either of these two electronic items will usually set a code.
Good luck and keep us posted.
Robyn

[KenDavis]

Thanks for the suggestions and no, no codes have been set, even when running rough.

[KenDavis]

Robyn, thanks for the suggestions. I replaced the wastegate solenoid, it was cheap. In checking the vacuum lines from the wastegate solenoid to the turbo, one broke off in my hand. Was probably leaking before hand, easy fix. Also replaced the fuel lift pump. All problems seem to be gone. Enough fuel to run smooth and turbo back up and running. $110 is alot cheaper than the dealers $2300, lousy crooks.