Fuel - Pump Noise, Hesitation, Sag, No Start

Number: 92-227-6E

Section: 6E

Date: JUNE 1992

Corporate Bulletin No.: 276103

ASE No.: A1, A8



Subject:
FUEL PUMP RELATED DRIVEABILITY ISSUES


Model and Year:
1991-92 CAMARO, CAVALIER, CORSICA, BERETTA, LUMINA AND CORVETTE
1992 C1, K1, L/M AND S/T TRUCKS
1992 LUMINA APV



ENGINE APPLICATIONS:
Car VINs A, B, D, F, H, J, L, N, P, T, X, 1, 3, 4, 8
Truck VINs E, H, K, L, W, Z

VEHICLE/TRUCK APPLICATIONS:
1991-92 Model Year F, J, L, W, Y Cars
1992 Model Year C, K, L, M, S, T Trucks
1992 Model Year U Van



SUBJECT:
Fuel Pump Noise; Engine Hesitation, Sag, Loss of Power; or No Start (Fuel Pump or Contaminated Fuel Supply)



CONDITION:
Customer may comment of fuel pump noise/whine and/or cold start stall; engine hesitation, sag, loss of power; or check engine light with codes 32 or 44. Condition(s) may be intermittent, but would typically be experienced in the first 5 minutes of engine/vehicle operation.

CAUSE:
Possible fuel starvation.




The illustrated matrix is provided to help during diagnosis activities.



Diagnostic Aids:
1. Oxygen sensor reading biased toward lean when the engine is under load.
2. Fuel pressure drops or does not increase by at least 5 psi when throttle moves from idle to part throttle.
3. Fuel integrator values steadily increasing under load.
4. Intermittent condition temporarily eased when accelerator pedal is released. Condition returns when accelerator pedal is reapplied.
5. Complete loss of fuel pressure.

CORRECTION:
Use Section 6E3 of the appropriate service manual to diagnose possible fuel system related problems. The vehicle may need to be operated under a load while monitoring fuel pressure to detect the problem.

IMPORTANT:
MAKE CERTAIN THE FUEL SYSTEM IS PERFORMING TO SPECIFICATIONS BEFORE OTHER ENGINE CONTROL SYSTEM COMPONENTS ARE SERVICED.

PROCEDURE:
Follow procedures identified in the appropriate service manual or: for 1992 "J" vehicles specifically, see Dealer Service Bulletin No. 92-176-6C, dated April 1992; for electrical intermittents, see Dealer Service Bulletin No. 92-05-8A, 86-56 and 88-101-8A as well as Section 8A of the service manual and instruction in required tool J-38125 usage.