Wagoneer L4-150 2.5L VIN E TBI (1990)
Fuel Pressure Regulator: Adjustments
Throttle Body Pressure Test Port
1.
Remove the plug from the pressure test port on the throttle body.
2.
Install a pressure test fitting in place of the plug, and connect a 0-207 kPa (0-30 psi) fuel pressure gauge to the test fitting.
3.
START engine and allow it to idle. The pressure gauge should read 97-103 kPa (14-15 psi). If the fuel pressure reading is within this range the
pump is operating correctly, and no further testing is necessary.
Fuel Pressure Regulator Adjustment
4.
If the fuel pressure reading is low, turn the pressure adjusting screw inward to increase the fuel pressure to the correct range. If the fuel pressure
increases to the correct range, no further testing or adjustment is required. If the fuel pressure fails to increase proceed to step 6.
5.
If the fuel pressure reading is high, turn the pressure adjusting screw outward to decrease the fuel pressure to the correct range. If the fuel pressure
decreases to the correct range, no further testing or adjustment is required. If the fuel pressure fails to decrease proceed to step 7.
6.
If the fuel pressure remains too low after attempting to adjust the pressure, momentarily pinch the fuel return line, and check the fuel pressure
reading on the gauge. If the pressure increases rapidly with the return line pinched, the fuel pressure regulator is defective, and must be replaced.
If the fuel pressure fails to increase proceed to step 8.
7.
If the fuel pressure remains too high after attempting adjustment, check the fuel return line, and tank fittings for obstructions. Clear any
obstructions found and retest. If no obstructions are found the fuel pressure regulator is defective and must be replaced.
8.
If the fuel pressure fails to increase with the fuel return line pinched off, connect an in-line pressure gauge between the fuel pump and the fuel filter
. If no pressure difference is noted on either pressure gauge the fuel pump is defective and must be replaced. If a 35 kPa (5 psi) or greater reading
is achieved on the gauge between the pump and filter, the fuel filter is plugged and must be replaced.
