1988 Audi 90 Audi 90 Quattro Chugs and stalls

RENNSPORTROSS

MEMBER
1988 AUDI 90

Engine Mechanical problem
1988 Audi 90 All Wheel Drive Manual

I have a 1988 Audi 90 Quattro. When the car sits for an hour or so, it runs perfect. About 3-5 miles after driving it, I will come to a stop and it will stall. Almost as if it is losing power. After it stalls, it takes a couple minutes to start it back up. Once it is started it chugs in every gear while going down the road, and tries to die out. At this point I must have the gas pedal to the floor to keep the engine running. I have replaced the fuel distributor, and the fuel pressure regulator. Both OEM. The fuel pump has pressure and runs fine. Maybe the fuel pump is shutting off. When The fuel gets below a quarter tank it chugs worse and dies out as soon as I come to a stop and try to accelerate. I checked the fuel pump and It was giving out good pressure, I also checked the fuel filter, Its good but I will replace it.

There was a security feature added sometime in its life to prevent theft, It was wired to the cold start valve, and after every time you restart it you must push that button. Would that contribute to the problem?

1 Reply

DAVE H

MECHANIC
13,383 POSTS

Hello .. thanks for the donation .. much appreciated

You need to check the pump is supplying the correct pressure to the engine .. a working pump does not mean it is a good pump .. the correct pressure is vital to engine running conditions

hoFUEL INJECTION SYSTEM
System Pressure
Remove fuel line from cold start valve. See Fig. 9 . Remove test plug from distributor lower chamber. Connect Pressure Gauge (VW 1318 ) between fuel line from cold start valve and lower chamber. See Fig. 9 .
Disconnect differential pressure regulator connector from side of regulator. Remove fuel pump relay. Jumper fuel pump relay socket. Open valve on pressure gauge.
Energize fuel pump. Note pressure reading on pressure gauge. Pressure should be 88-94 psi (6.2-6.6 kg/cm2 ). System pressure is not adjustable.

Fig. 9: Checking Fuel Injection System Pressure