S. Fuel Pressure and Residual Pressure

S. Fuel pressure and residual pressure

S1




Checking of vacuum hose for pressure regulator
- Undo the vacuum hose from the pressure regulator.
- Check if the hose is not tight by blowing into it.

If the hose is OK:
^ Connection of pressure gauge S2.

If the hose is tight:
^ Check the hoses and nipples and rectify the fault.

S2




Connection of pressure gauge
Engine without quick-release coupling
- Ignition off.
- Connect gauge between fuel pipe and distribution pipe. Use hose 5116 and nipple 5265.
- Plug the gauge free hose end with plug 5266.
- Set the tap on 5011 in position 1 (pointing towards hose 5116).
^ Continue with Start of fuel pump 53.




Engine with quick-release coupling
- Connect nipple 9725 and adapter 5479 to the pressure gauge.
- Plug the gauge tree hose end with plug 5266.
^ Connect the adapter to the valve on the distribution pipe.
^ Continue with Start of fuel pump S3.

S3




Start of fuel pump
- Lift the electrical distribution box and remove the [1][2]system relay.
- Connect an electrical wire between connector 30 and 87/2 in the relay socket.
The fuel pump should now start.
^ Continue with Measurement of system pressure S4.

S4




Measurement of system pressure
- Read the system pressure on the pressure gauge. System pressure should be 300 kPa (43.5 psi).

If system pressure is too low:
^ Low system pressure S5.

If system pressure is too high:
^ High system pressure S6.

If system pressure is normal:
^ Checking the pressure regulator S7.

S5




Low system pressure.
- Squeeze together the return pipe with your hand and check if the pressure rises.

Important! Do not allow the pressure to rise higher than 600 kPa (87 psi).

If the pressure rises rapidly:
^ Pump and pipes are OK. Replace the pressure regulator and measure system pressure once again.

If pressure rises slowly:
^ Indicates clogging in the fuel filter, fuel pump strainer or fuel pipes.

If pressure does not rise:
^ Indicates a defective fuel pump.

S6




High system pressure.
- Ignition off
- Remove the cable from the fuel pump relay socket.
- Remove the return pipe from the pressure regulator.
Blow into the pipe.

If the pipe is OK:
^ Faulty pressure regulator. Test with a new regulator and measure system pressure again.

If the pipe is tight:
^ Check the return pipe.

S7




Checking the pressure regulator
- Connect a vacuum pump to the pressure regulator. Use vacuum pump 5843, for example.
- Pump the air out of the regulator.
Check that the drop In system pressure matches the drop in pressure in the regulator.
300 kPa (43.5 psi) - negative pressure = system pressure.
- Disconnect the hose from the vacuum pump. System pressure should return to 300 kPa.
^ Continue with Stop fuel pump 88.

S8




Stop fuel pump
Remove the electric wire between the relay's socket connectors, 30 and 87/2. Return the relay.
^ Continue with Checking the residual pressure S9.

S9




Checking residual pressure
The pressure should drop below 200 kPa (29 psi) in less than 20 minutes.

If residual pressure Is OK:
^ Disconnect pressure gauge S10.

If pressure drops too quickly:
^ Check that the injection and cold start valves do not leak fuel.

If the valves are free from fault:
^ Test with a new pressure regulator.
^ Disconnecting pressure gauge S10.

S10




Disconnecting pressure gauge
- Ignition off.
Hold some paper under the fuel pipe to soak up the petrol which runs out when the pressure gauge is removed.

Important! The plastic band for the fuel pipe, which may have been removed, must be returned.