is there a fuel return sensor and if so where is it located?
Where is the fuel injection fuses located?
The fuel injectors are operated by the PCM – Powertrain Control Module. This is the engines computer. The PCM has 2 main fuses and a PCM Power Relay. They are located in the engine compartment fuse panel. Fuse U and Fuse C, both 30 amp fuses.
1994 Ford E-350 5.8L Engine Wiring Diagram 11994-ford-e-350-5.8l-engine-controls-1-of-2
1994 Ford E-350 5.8L Engine Wiring Diagram 21994-ford-e-350-5.8l-engine-controls-2-of-2
Fuel Injector Pressure Test
- Connect pressure gauge T80L–9974–A, or equivalent, to the fuel pressure test fitting. Disconnect the coil connector from the coil. Disconnect the electrical lead from one injector and pressurize the fuel system. Disable the fuel pump by disconnecting the inertia switch or the fuel pump relay and observe the pressure gauge reading.
- Crank the engine for 2 seconds. Turn the ignition OFF and wait 5 seconds, then observe the pressure drop. If the pressure drop is 2–16 psi (14–110 kPa), the injector is operating properly. Reconnect the injector, activate the fuel pump, then repeat the procedure for other injector.
- If the pressure drop is less than 2 psi (14 kPa) or more than 16 psi (110 kPa), switch the electrical connectors on injectors and repeat the test. If the pressure drop is still incorrect, replace the disconnected injector with one of the same color code, then reconnect both injectors properly and repeat the test.
- Disconnect and plug the vacuum hose at EGR valve. It may be necessary to disconnect the idle air control valve and use the throttle body stop screw to set the engine speed. Start and run the engine at 1,800 rpm (2,000 rpm on 1984 and later models). Disconnect the left injector electrical connector. Note the rpm after the engine stabilizes (around 1,200 rpm). Reconnect the injector and allow the engine to return to high idle.
- Perform the same procedure for the right injector. Note the difference between the rpm readings of the left and right injectors. If the difference is 100 rpm or less, check the oxygen sensor. If the difference is more than 100 rpm, replace both injectors.