Fuel Pump: Testing and Inspection
Checking Quantity Delivered By Fuel Pump
Tools
Tools:
Preliminary work
1. Open the bonnet.
2. Open lid of central electrics box. To do this, loosen the four fastening screws.
3. Remove fuses -3- for the ignition rod modules, -4- injection system and both fuel pump relays (left pump -1- and right pump -2-).
4. Pull the design cover up and off.
5. Remove engine compartment cover at middle rear and left.
6. Loosen left cable guide of ignition coil cable at the plastic clips for the intake-air distributor and fold it up for better access to the fuel supply at the fuel distributor.
Tools and materials
Special tools
Special Tools:
Information
Test conditions
- The battery voltage must not be < 12 volts.
- Fuel system parts must not get dirty.
Checking quantity of fuel delivered
DANGER: Danger of poisoning from fuels.
- Gasoline is toxic.
- Inhaling vapours can cause irritation of the mucous membranes and eyes.
- It can be carcinogenic. It represents a serious risk to health when inhaled, touched or swallowed over longer periods.
- Only work on the fuel system in well-ventilated rooms.
- Wear protective gloves that are fuel-resistant.
- Wear a breathing mask with active charcoal filter; do not breathe in any fuel vapours.
- Ensure that there is adequate ventilation and extract all fuel vapours.
- Before opening the fuel lines or fuel hoses, relieve the fuel pressure.
- Collect escaping fuel, absorb it if necessary with a suitable binding material and dispose of properly.
- Pay attention to cleanliness when working on the fuel system.
DANGER: Danger of fire from fuel.
- Keep clear of ignition sources.
- Do not smoke.
- Disconnect battery.
- Danger of fire due to naked flames and sparks, e.g. during welding or grinding work.
- Danger of fire due to escaping fuel, e.g. on hot engine components or due to electrostatic charge. Allow engine to cool down.
- Secure the vehicle, e.g. with a warning sign.
- Change any clothing soaked with fuel immediately.
- In case of fire, use CO2 or dry powder fire extinguishers.
NOTE:
- The ignition must be switched off when working on the fuel system.
- Absorb any escaping fuel using a suitable binding material or a cloth.
- Cloths which have absorbed fuel must be disposed of according to the applicable national laws.
- The fuel system must be depressurized before starting work on it.
- Only work on the fuel system in well-ventilated rooms.
- Any seals which have been removed must always be replaced.
- The fuel gallery is pressurized. Place a cloth under the areas of the fuel gallery to be opened so that fuel does not drip on to hot engine parts.
1. Twist off the cap of the fuel scavenging valve -1-.
NOTE: Proceed as follows to fit the adapter 1318/20 -2- to the scavenging valve: Turn the valve -4- anti-clockwise at the T-piece until the valve is closed. Place the adapter on the scavenging valve and use the knurled nut -3- to fit the adapter in a clockwise direction until the adapter is attached securely to the scavenging valve. To open the scavenging valve, turn the T-piece of the valve clockwise (the fuel is released immediately and flows out via the adapter 1318/20). If the T-piece touches the intake-air distributor when you turn it, shorten the cross-pin of the T-piece slightly so that it has sufficient clearance. The adapter 1318/20 includes a hose connection 1318/20-1 -1-, to which a suitable fuel hose can be fitted using a screw-type clamp.
2. Relieve the fuel pressure. To do this, fit adapter 1318/20 -1- together with 1318/20-1 -2- and a suitable hose to the scavenging valve and relieve the fuel pressure into a cloth (screw T-piece on clockwise). Only a small quantity flows out. Close the T-piece on the adapter again (unscrew T-piece anti-clockwise).
3. Pull fuel supply hose off the fuel gallery. To do this, place a cloth underneath, loosen the clamp and pull off the fuel supply hose. Catch any dripping fuel.
NOTE: Make sure that the switch on the adapter 9479 is at 0 so that fuel is not pumped immediately when you connect the adapter.
4. Hold fuel supply hose into measuring cup -2 and 3- and insert adapter 9479 into the relay slot of the fuel pump relay for the left pump -1-.
NOTE: To avoid incorrect readings, ensure that the hoses are already filled with fuel when you start the test.
5. Switch fuel pump on using the adapter 9479 until fuel emerges at the end of the hose. Then empty the measuring cup. This removes the remaining air from the hose.
NOTE: Get a second person to record the time for checking the quantity of fuel delivered.
6. Start the fuel supply in order to measure it. The left pump should supply at least 800 ml of fuel after around 15 seconds. The quantity of fuel delivered for both pumps should be at least 800 ml after around 10 seconds (insert adapter 9479 into both relay slots at the same time and switch it on for this). Empty the measuring cup between measurements.
7. If the specified fuel quantities are not delivered, check the fuel lines for kinks and bends and check the fuel filter and power consumption of the pumps.
8. Fit the fuel supply hose after you have measured the fuel quantity. To do this, push the fuel supply hose on to the connection piece and fit a clamp.
9. Remove adapter 1318/20 and hose. To do this, turn the knurled nut anti-clockwise until the adapter comes off the scavenging valve.
Subsequent work
1. Attach left cable guide for ignition coil cable to the plastic clips for the intake-air distributor.
2. Insert fuses -3- for the ignition rod modules, -4- injection system and both fuel pump relays (left pump -1- and right pump -2-).
3. Fit lid of central electrics box. To do this, fit the four fastening screws.
4. Install engine compartment cover at middle rear and left.
5. Fit the design cover.