Residual Pressure
- Connect Pressure Gauge (VAG 1318) between fuel supply line and fuel rail. Open pressure gauge lever. Start engine. Turn off engine. Wait 10 minutes. Residual pressure should be 44 psi (3.1 kg/cm2 ) on Cabriolet and 90 modles; 48 psi (3.4 kg/cm2 ) on 100 models. After 20 minutes, residual pressure should be 32 psi (2.2 kg/cm2 ) on Cabriolet and 90 models; 46 psi (3.2 kg/cm2 ) on 100 models.
- If system fuel pressure is low, check fuel pump check valve, sensor plate free play, fuel distributor "O" rings and seats. Replace if necessary. If these components are okay, replace fuel pressure regulator.