Previous, Next, Contents, Home.

Checking Fuel Supply to Injectors

When troubleshooting starting problems, check to determine whether fuel is being delivered to the injectors. First check visually for fuel leaks at the injector pipe unions or around the injector pump timing plug. To test fuel delivery, slightly loosen the fuel union nut on the fuel injector pipe for No. 1 cylinder, either at the pump or at the injector. See Fig. 3-1. Crank the engine and look for signs of fuel leakage at the loosened union.

WARNING-

Loosen the nut only about one-quarter to one-half turn to limit the amount of fuel leakage. The fuel injection system operates at very high pressure. Keep hands and eyes clear. Wear heavy gloves and eye protection.

WARNING-

Fuel will be expelled. Do not smoke or work near heaters or other fire hazards. Have a fire extinguisher handy.

CAUTION-

Diesel fuel is damaging to rubber. Wipe off any fuel that spills on hoses, wiring, and rubber steering and suspension parts, and wash with soap and water.

Fig. 3-1. Open end box wrench (Volkswagen special tool no. 3035 or equivalent) being used to loosen fuel union nut at the injector.

If no fuel is observed during this test, the most likely cause is a restriction or air leak in the fuel lines between the fuel tank and the injection pump, or a clogged fuel filter.

If fuel is observed but the engine still fails to start, possible causes are incorrect valve timing (see ENGINE) or incorrect injection pump timing (5.5 Injection Pump)..

When finished testing, tighten the fuel union nut and torque to 25 Nm (18 ft. lb.).

Previous, Next, Contents, Home.