X. Fuel Pressure and Residual Pressure

X. Fuel pressure and residual pressure

X1




Checking the pressure regulator vacuum hose
- Remove the vacuum hose from the pressure regulator.
- Check that the hose is not blocked by blowing into it.

If the hose is OK:
^ Connect the fuel pressure gauge X2.

If the hose is blocked:
^ Check hoses and nipples and remedy the fault.

X2

Connecting the fuel pressure gauge



Engine without quick connector
- Ignition off.
- Connect the fuel pressure gauge between the fuel line and the distributor pipe. Use hose 5116 and nipple 5265.
- Plug the free end of the meter's hose with plug 5266.
- Set the valve on 5011 to position 1 (pointing towards hose 5116).
^ Continue with Starting FP X3.




Engines with quick connectors
- Connect nipple 9725 and adapter 5479 to the pressure gauge.
- Plug the free end of the pressure gauge hose using a 5266 plug.
- Connect the adapter to the valve on the distributor pipe.
^ Continue with Starting FP X3.

X3




Starting fuel pump (FP)
- Lift out the central electrical module and remove the [1][2]system relay.
- Connect a wire terminal 30 and 87/2 on the relay board.
The FP should now start.
^ Continue with Measuring system pressure X4.

WARNING! Jump connecting between the wrong terminals will destroy the LH control module!

X4




Measuring system pressure
- Read the system pressure on the pressure gauge.
The system pressure should be 300 kPa (43psi).

If the system pressure is too low:
^ System pressure too low X5.

If the system pressure is too high:
^ System pressure too high X6.

If the system pressure is normal:
^ Check the pressure regulator X7.

X5




System pressure too low
- Pinch the return lead and check to see it pressure rises.

Important! Do not let pressure exceed 600 kPa (85psi).

If the pressure rises quickly:
The pump and pipes are OK.
^ Try using a new pressure regulator.
^ Check that system pressure is normal.
^ To disconnect, continue with Disconnecting pressure gauge X10.

If pressure rises slowly:
^ Check the fuel filter, tank pump strainer and fuel line for blockages.
^ Check that system pressure is normal.
^ To disconnect, continue with Disconnecting pressure gauge X10.

If pressure does not rise:
^ Try using a new FP.
^ Check that system pressure is normal.
^ To disconnect, continue with Disconnecting pressure gauge X10.

X6




System pressure too high
- Ignition off.
- Remove the wire from the FP relay board.
- Remove the return line from the pressure regulator. Blow into the line.

If the line is OK:
^ Try using a new pressure regulator.
^ Check that system pressure is normal.
^ To disconnect, continue with Disconnecting pressure gauge X10.

If the line Is blocked:
^ Check the line for pinching and clogging.
^ Check that system pressure is normal.
^ To disconnect, continue with Disconnecting pressure gauge X10.

X7




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 system pressure decreases as much as the pressure in the regulator.
300 kPa (43 psi) - partial vacuum = system pressure.
- Disconnect the hose from the vacuum pump. System pressure should return to 300 kPa (43 psi).
^ Continue with Stopping the fuel pump (FP) X8.

X8




Stopping the fuel pump (FP)
Remove the wire between the relay board terminals 30 and 87/2. Replace the relay.
^ Continue with Checking residual pressure X9.

X9




Checking residual pressure
Pressure must not sink below 200 kPa (28 psi) in less than 20 minutes.

If residual pressure is OK:
^ Disconnecting pressure gauge X10.

If pressure decreases too quickly:
^ Check that the injectors or cold start valve are not leaking fuel.

If the valves are OK:
^ Try using a new pressure regulator.
^ Disconnecting pressure gauge X10.

X10




Disconnecting pressure gauge
- Ignition off.
Hold some paper under the fuel line to absorb fuel that runs out when the pressure gauge is disconnected.

Important! Plastic fuel line ties which were removed must be replaced.