Fuel - Extended Crank, Driveability/Low Fuel Pressure
85olds1SUBJECT EXTENDED ENGINE CRANKING TIME NUMBER: 85-T-52
AND/OR VEHICLE DOES NOT MAINTAIN FUEL RAIL PRESSURE
DATE: Nov.. 15, 1985
MODELS/YEARS 1984 CUTLASS CIERA & 1985 FIRENZA,
CALAIS, CUTLASS CIERA, & NINETY-EIGHT SECTION: 6E
EQUIPPED WITH MPFI ENGINES
Some 1984 and 1985 vehicles equipped with MPFI engines may experience extended engine cranking time, poor driveability, engine will not stay running, and/or vehicle may not maintain fuel rail pressure.
FIGURE 1:
Chart A-7 in Section 6E3 of the Oldsmobile Chassis Service Manual states that while performing the "Fuel System Diagnosis" procedure, if the fuel rail pressure does not hold, but will maintain pressure while pinching the pressure line flex hose, the problem is either a leaking pump coupling hose or a faulty in-tank pump. However, the problem could also be a leaking fuel sender pulsator. See Figure 1.
A simple test to determine which component is causing a pressure line leak-down can be performed in the following manner:
1. Remove the sending unit assembly from tank.
2. With the fuel pick-up sock still attached, submerge the sender assembly in CLEAN water far enough to completely cover the fuel pump and pulsator.
3. Apply regulated air pressure (not to exceed 20 psi) to the pressure line of the sending unit assembly.
4. Watch for air escaping from around the pulsator or the end of the pump to determine which component is leaking.
5. Replace parts as necessary and recheck.
NOTICE: Do NOT leave sender submerged in water for extended periods of time; blow dry immediately upon removal.
The new part number for the pulsator is 6472359 and is available through WDDGM.