Fuel Pressure: Testing and Inspection

CAPACITY (VOLUME) TEST

1. Break loose the fuel line fitting at the fuel filter and allow the pressure to release, then disconnect the fuel line at the fuel filter.

NOTE: Use care to prevent ignition of spilled fuel.

2. Place a suitable, non-breakable container (1/2 liter or 1 pint minimum) at the end of the disconnected fuel line (a piece of hose may be needed on the fuel line end). Crank engine ten seconds. The fuel pump should deliver a minimum of 1/3 pint of fuel.
3. If fuel volume is sufficient, proceed with the pressure test.
4. If fuel flow is low, repeat test using a remote non-breakable container of diesel fuel.
a. Remove fuel hose from fuel pump inlet supply line. Connect a length of fuel hose from the fuel supply line to the non-breakable container and repeat Step 3.
b. If fuel flow is to specification, the problem is either a plugged fuel/water separator or a kinked/leaking fuel hose. Service as necessary.
5. If fuel flow does not meet specification, replace fuel pump.

PRESSURE TEST

1. Connect fuel pump pressure tester to the injection pump end of the fuel line. ("T" is not required).
2. Crank the engine for 10 seconds and read the pressure. If pump pressure is not 6-8 PSI (41-55 kPa) install a new fuel pump.
3. Connect fuel line.