Here is the procedure for checking fuel pressure.
FUEL PRESSURE FULL LOAD
FROM FORM EGED-150
8. FUEL PRESSURE FULL LOAD
Measure fuel pressure at fuel filter bleeder
Measure pressure at full load rated speed
0-160 PSI Gauge
20 PSI minimum
? If pressure is low, replace fuel filter, clean fuel strainer and retest
? If pressure still low, perform Test 2B
NOTE: TESTS 8.9 & 10 MAY BE PERFORMED SIMULTANEOUSLY AT FULL LOAD CONDITIONS
To determine if the fuel system is supplying the engine with the proper fuel quantity and pressure at full load conditions.
NOTE: If fuel filter is equipped with a water-in-fuel probe, check with vehicle operator to determine if the water-in-fuel lamp has been illuminated during vehicle operation.
1. If pressure gauge was not connected to fuel system in Test 2, remove air bleed valve Figure 2.35 on fuel filter header. Install 1/8 inch (3 mm) pipe fitting in place of the bleed valve..
2. Connect a line from the fitting to the 0-160 PSI gauge of the Model D-200 Pressure Test Kit (ZTSE-2239) or Gauge Bar (PS94-831-3) Figures 2.36 & 2.37 . Start engine and run at low idle to check for fuel leaks in line to pressure gauge.
NOTE: Bleed air from the fuel line to insure an accurate reading.
3. Drive vehicle on road till engine reaches operating temperature. Find an open section of road and select a suitable gear. Depress the accelerator pedal (full depression) to the floor and accelerate to rated speed and 100% load.
NOTE: Driving the vehicle up hill or fully loaded will facilitate efforts of reaching the proper engine loading at rated engine speed.
4. Measure fuel pressure and record on diagnostic form. If pressure is not within specifications, replace fuel filter, clean fuel strainer and re-check fuel pressure.
NOTE: It may take a number of crank cycles to purge the air out of the fuel system after replacing the fuel filter.
If fuel pressure remains low after replacing the filter, perform Transfer Pump Restriction Test 2B.
- A fuel filter or clogged fuel strainer could cause high restriction and low fuel pressure because of dirt or fuel jelling in cold ambient temperatures. -- Replace fuel filter, clean strainer and re-test.
- Debris in the fuel regulator valve will cause low fuel pressure.--Refer to Test 2B.
- A kinked or severely bent fuel supply line or blockage at the pickup tube could cause restriction and therefore low fuel pressure.--Refer to Test 2B.
- A loose fuel line on the suction side of the fuel system could cause air to be ingested into the system and cause low fuel pressure.--Refer to Test 2B.
- The fuel pump could have internal damage, e.g. seized plunger or leaking check valves.