Fuel Pressure: Testing and Inspection
FUEL PUMP PRESSURE AND CHECK VALVE TESTChecking Fuel Pump Pressure And Check Valve:
1. Disconnect fuel inlet hose from fuel distributor and connect to fuel pressure gauge as shown in illustration (shut-off valve in closed position).
2. Operate fuel pump until gauge pressure reading is approx. 73 psi (5 bar), then turn pump "OFF". (Operate pump by bridging terminals of fuel pump relay socket as in step 2 of electrical test above.)
NOTE: If pressure excedes the specified value, bleed off excess pressure by carefully opening shut-off valve on gauge. Cover with clean rag to avoid spraying fuel.
If after one minute of pump operation the specified pressure is not reached, check for plugged fuel filter or kinked/pinched fuel supply line. If filter and line are OK, replace fuel pump.
3. Wait 10 minutes then observe residual pressure on gauge.
^ Should be 49 psi (3.4 bar) minimum.
If less than specified and there are no leaks, replace fuel pump check valve.
FUEL PUMP VOLUME TEST
1. Reconnect fuel supply line to fuel distributor (line must be connected because this test checks for adequate volume under normal pressure).
Checking Pump Volume From Fuel Return Line:
2. Disconnect fuel return line at connector next to fuel distributor (see illustration), and direct outlet from fuel distributor into suitable measuring container. You may need to add an extra piece of hose to do this safely.
3. Remove fuel filler cap.
4. Connect voltmeter between electrical terminals of fuel pump.
5. Energize fuel pump for 30 seconds (see step 2 of electrical test above) and note operating voltage at the pump.
Fuel Pump Volume Vs. Supply Voltage:
6. Check volume of fuel in container after 30 seconds of operation and compare with chart.
^ If volume is less than that specified for the noted operating voltage, check for restricted or plugged fuel filter and/or supply line. If filter and line are OK, replace fuel pump.