I bought a 93 Z28 that has been sitting about 5 years because of a bad fuel pump. The car is all stock. I put in a brand new fuel pump, fuel filter, injectors, and plugs. I purged the whole fuel system so it has fresh premium flowing through it and I'm getting great fuel pressure. The car is flashing a code 26 which I'm pretty sure is the air pump since it keeps blowing that fuse.

Question is would that cause it to run rough and have about half the power it should have all the time at any rpm? I'm thinking maybe a bad o2 sensor but is there any way to test them? 26 is the only code that the computer is giving off.

 

D26, or DTC 26 Quad-driver (QDM) #1 circut from the GM service ..i would check the operation of the EGR valve manually, if you do not have any tools. there is a diagnostic "tree to follow in the GM manual . If you have a fax machine i will send the sheet to you. Let me Know.
plattted@sbcglobal.net if you do have a fax, send your phone # Many , many things could be the cause of your driveability problems with a car sitting that long. From mice damage to cracked vaccum lines, moisture in the Opti, cracked wires.... Check one thing at a time. did you replace the vaccum line to the FP regulator after checking?

 

From Shoebox's code listing for the 93:

DTC 26

Quad-Driver Module (QDM) #1 circuit
applies to:
- AIR pump relay circuit
- EGR solenoid
- EVAP solenoid

None of those would put it down on power.

Have you checked the operation of the fuel pressure regulator? Checked the vacuum line for fuel?

 

IF your E G R was in the open position It certainly would.