My fuel pump relay will not click , the wire from the relay to the pcm , when you first turn key on the voltage will be b+ then it will drop off to 4.5 volts , is that norm , i have pulled the pcm and tested the wires and checked the wire to all other pins , all clean so the wire it good , does any one know if that is normal?, that truck has a bad hesitation ,but if you let up the tps just a little it is a lot better , at low speeds , on the freeway it does not hesitate, so at high rpms it's ok , any idea's ,thanks
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you will need to check the plug to the pump on top of the tank. check for voltage. then if no volts trace the wires back. also you should check the relay have some one at the relay listening to see if it clicks when you turn the key. no click no volts no volts may be a warn out relay, if it buzzes change it.
There is a red and white wire feeding the fuel pump relay from a 30 amp fuse. Both the shutdown relay and the fuel pump relay are grounded by the PCM, so if the fuel pump relay is grounded it should be "on" and providing a direct link from the pump to that fuse. You should have battery voltage on that 30 amp wire before the relay and then on the dark green and black wire going to the pump. If you don't have battery voltage coming from the 30 amp fuse, the problem could be before the fuse. That 30 amp fuse is hot all the time, so it is powered by a fuseable link coming off the battery.
I apologize for a delayed response as i was not at my desk.
Check to see if the fuel pump relay clicks when you turn the key on. If
it doesnt click verify one terminal has constant ground if not you will
need to run a new ground wire. If ground is good access pin 46 on
connector 1 of the pcm to check for voltage if no voltage replace pcm if
it has voltage replace green/white wire between pcm and relay. You can
also first try to swap the relay with another one to see if that helps.
If relay clicks then check the 15 amp fuel pump fuse and if blown
replace. If fuse is good verify one terminal on the relay has voltage
at all times and gray wire has voltage leaving relay when key is in
crank position for for a few seconds when turned into on position. If
gray wire leaving relay has voltage but not gray wire at fuel pump
replace the wire.
you can try this:
It is possible with a P0232 for the fuel pump to be running continuously, even with the ignition off. If that's the case and you can hear the fuel pump running, you may be able to disregard some of the following checks. Turn the KOEO (key on engine off) and wait for a few seconds. This allows the PCM to complete it's fuel pump pre-cycle. Now, using your scan tool (if you have one) observe the FP VOLTAGE FEEDBACK reading in the datastream. This reading indicates what kind of voltage the fuel pump is receiving.
If you don't have access to a scan tool, use a voltmeter to read the FP voltage at the fuel tank. If your reading shows any voltage at all present to the fuel pump with KOEO (or if you can hear the pump running), remove the FP relay. If the voltage remains, or the fuel pump continues to run, then there is a short to voltage on the FP voltage supply circuit or on the feedback circuit. Repair as necessary. If the voltage disappears (or the pump quits running) with the FP relay removed then try replacing the relay with a spare one. Upon reinstalling the spare relay, if the voltage disappears, the relay was faulty due to a short. If, though, after replacing the relay voltage is still present, suspect that the PCM FP relay control circuit is shorted to ground.
Check for a short to ground on the PCM FP relay control (ground driver) circuit by removing the FP relay and ohm between a good ground and the PCM FP relay control. There should be no continuity to ground with KOEO (after the FP pre-cycle is completed). If there is continuity to ground the wire is shorted. Find the short to ground and repair as necessary. If you can find no physical short, It may be necessary to snip the FP relay control wire close to the PCM connector where it will be easy to repair and check for continuity to ground with KOEO coming OUT of the PCM. If there is no continuity the wire is shorted in the harness. But if continuity exists, the driver may be internally shorted to ground and the PCM may require replacement.
No noise from fuel pump when you turn over the car .First thing get voltage at fuel pump relay checked, is there 12 volt to the relay.If no, then problem is again the relay.---------
To reconfirm the problem, try other test, that is remove the relay and by pass the relay terminals with a jumper wire .Then with 12 volt external battery give power to fuel pump connector and see, if the fuel pump starts, then its clear that fuel pump relay is faulty.----------- Also other problem can be fuel pump inertia switch.If the inertia switch is faulty then also fuel pump will not start.--------
The fuel pump relay on a 1995 Ford Explorer is in the power distribution box, in the engine compartment, driver's side near the firewall.---------- The fuel pump inertia switch is in the right front passenger area it is below the dash but above the carpet in the right hand corner.-------- Its a push button type inertia switch. -------- Fuel Pump Activation When ignition switch is turned to START position, PCM operates fuel pump relay to provide fuel for starting engine. PCM senses engine speed and shuts off fuel pump by opening ground circuit to fuel pump relay when engine stops or engine speed drops to less than 120 RPM. When ignition switch is in ON position, EEC power relay is energized (contacts closed). Power is provided to fuel pump relay and timer in PCM. Fuel pump receives power through fuel pump relay contacts. Inertia Fuel Shutoff (IFS) Switch All models use an electrical interrupt switch in fuel system. During a collision or vehicle rollover, electrical contacts within inertia switch open, shutting off fuel supply to electric fuel pump. Fuel supply is interrupted even when engine is running. A reset button is located on switch assembly. If electrical circuit trips, vehicle will not restart until switch is reset. Fuel system should be inspected before resetting switch. IFS switch is located under instrument panel, near right side of transmission hump.-----------If the fuel pump relay, the inertia switch and fuel pump all checked ok, and fuel pump is working with direct 12 volt source to fuel pump.Then problem relates to computer.The computer (power control module, PCM) is faulty and has to be replaced.---------This will help.Thanks.Helpmech.
You can usually go by the wire colors. The fuel pump relay wires are pink, gray, black, and green with a white stripe. When troubleshooting a fuel pump that is not coming on, the relay is the best place to figure out why. You can pull the relay out and put a jumper wire from the battery to the terminal with the gray wire. If the pump runs, you know that isn't the problem. Then turn the key on and use a jumper between the terminals with the pink and gray wires. If this turns the pump on, you know the ignition switch is sending power to the relay, and the fuse is good. Pull that jumper out, but leave the key on. Push the relay back into the socket, but put a jumper from a ground point to the terminal with the black wire. If that turns the pump on, the ground wire is bad. If not, the PCM is not turning the relay on. Reasons for that may be a bad wire from the PCM, a passlock issue, or the PCM fuse/power wire.
INSTALL PRESSURE GUAGE THEN CK, VOLTAGE TO PUMP PCM TURNS ON PUMP RELAY FOR 2 SECONDS WHEN KEY CYCLED ON ,, IF NO POWER CK INERTIA SWITCH ( MAY BE TRIPPED ) IF NO POWER TO INERTIA SWITCH CK FUEL PUMP RELAY IF NO VOLTAGE AT PUMP RELAY THEN CHECK FOR SPARK AT PLUGS IF NO SPARK CK PCM POWER RELAY IT SUPPLIES VOLTAGE TO PCM THAT INTURN POWERS FUEL PUMP RELAY
im not sure of the color wires that should be powered but have you checked the fuel pump relay under the hood? also check that you have a good ground at the pump dont check just the positive voltage check for negative (ground) also