Fuel Pressure Regulator and Residual Pressure, Checking - II

Fuel Pressure Regulator And Residual Pressure, Checking

The fuel pressure regulator controls the fuel pressure and is dependent on intake manifold pressure.

Special tools, testers and auxiliary items required







- Pressure Gauge V.A.G 1318







- Pressure Gauge Adapter V.A.G 1318/6+7

Test sequence







- Remove fuse No. 28 (fuel pump) from fuse holder.

CAUTION: Fuel supply line is under pressure. Wear eye protection and protective clothing in order to avoid injuries by contact with fuel. Before removing from hose connection wrap a cloth around the connection. Then release pressure by carefully pulling hose off connection.







- Disconnect fuel supply line from fuel distributor - arrow - and catch escaping fuel using a rag.







- Connect Pressure Gauge V.A.G 1318 to supply line -1- and to fuel distributor using Adapters VAG1318/6+7 VAG1318/6+7.
- Open shutoff valve of Pressure Gauge. The lever points in direction of flow.
- Install fuse 28 (fuel pump) into fuse holder.
- Start the engine and run at idle speed.
- Measure fuel pressure.
- Specification: approx. 3.5 bar positive pressure







- Pull the vacuum hose off from fuel pressure regulator - arrow -.
- Fuel pressure must rise to approx. 4.0 bar positive pressure.

If the specification is not obtained:
- Check delivery rate of fuel pump.
- Vehicles with front wheel drive: Fuel Pump, Checking
- Vehicles with all wheel drive: Fuel Pump, Checking

If the specification is obtained:
- Switch off ignition.
- Check for leaks and holding pressure. Observe pressure drop on Pressure Gauge.
- After 10 minutes there must be a residual pressure of at least 2.0 bar.

If the holding pressure drops below 2 bar:
- Start the engine and run at idle speed.







- Wait until pressure has risen, and then switch off ignition. Simultaneously close shutoff valve of Pressure Gauge V.A.G 1318 (lever perpendicular to direction of flow - arrow -).
- Watch pressure drop on gauge.

If the pressure does not drop:
- Test check valve of fuel pump.
- Vehicles with front wheel drive
- Vehicles with all wheel drive

If the pressure drops again:
- Check Pressure Gauge V.A.G 1318 for proper seal.
- Check whether line connections, O-rings in fuel distributor, and Fuel Injectors are properly sealed.

If no leaks are found:
- Replace fuel pressure regulator.

NOTE: Before removing Pressure Gauge, place cleaning rags again around line connection which is to be disconnected and remove fuse 28 from fuse holder again.