Engine Performance- Poor Driveability

91audi01

Group: 20

Number: 91-07

Date: March 31, 1991



Subject: Engine - Loss of Power - Hard Starting/Rough Idle Poor Acceleration/Performance

Model(s): 1986 Through 1988 5000S and 5000 Turbo Vehicles
1989 100 and 200 Vehicles up to VIN: 44KN017651 (supercedes Technical Bulletin 20-90-05 of 12-31-90)


Cause:

Protective coating on side of fuel tank loosens and migrates to fuel pump inlet screen, where, over time, flow is gradually reduced through the pump inlet screen. This substance can be identified as a brown waxy residue.

Production change:

Vehicles built after VIN: 44KN017651 do not use this protective coating.

Service solution:

Inspect the fuel pump inlet strainer for a brown, waxy residue. Use the following procedure for vehicles having this condition.

WARNING

Fire hazard. Do NOT smoke or have anything in area that can ignite fuel.

^ fuel tank must not be more than half full

^ refer to Repair Group 20 of Repair microfiche for fuel tank/pump component layout

^ carefully note position of all hoses, wires and clips; components must be reinstalled in exactly same position

^ disconnect and remove fuel pump from fuel tank

^ disassemble and remove nylon mounting bracket from fuel pump





^ lay pump on edge of work surface and grasp firmly with hand

CAUTION

Do NOT clamp against the centrally located rib on pump body.

Note

Clamping pump in a vise with wooden blocks is advisable only when extreme care is taken not to over-tighten the vise.





^ remove inlet screen at base of pump by cutting screen material as close as possible to the crimp (using a sturdy sharp knife) leaving as few strands of filter material as possible

^ hold knife parallel to the pump or at a slight angle away from center while cutting to ensure maximum removal of screen material





CAUTION

In practice, some material will be left after cutting. Remove any remaining strands of wire using needle nose pliers. Loose or residual material could later be drawn into the pump causing binding or seizure.

^ gently knock pump against a flat surface to shake loose any remaining screen material or debris

^ use compressed air to blow any loose screen material "away" from the pump

^ do not blow material "into" the internal pump area

Note

Be sure that all hoses, wires, clips and components are reinstalled exactly as they were before the modification.

^ reassemble pump and re-install in vehicle

^ perform quality check to assure proper pump operation

If the pump is noisy or pump performance is reduced after performing this modification

^ install new pump of the same type, however; the new pump must be modified by removing the screen as previously described

Modify fuel pump 125 t.u.

Quality check 10 t.u.

Labor operation: 2066510