Fuel pump relay
Junior User
Joined: Oct 2003
Posts: 56
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From: NC
Hello ymtrebel806. Welcome to the forum, the best place for advice I've found. Sorry it's taken so long to get back to you. I'm pretty sure that power goes from inertia switch to fuel pump. If you're not getting power to the inertia switch, I would try changing the fuel pump relay. They're cheap and I have seen bad new ones. Hope this helps.
Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
Good grief, how did we all overlook this call for help so long!!!!
I agree with chucknc, suspect the fuelpump relay, it feeds the inertia switch & it's located in the under hood main power distribution box located on the drivers side firewall.
You can try thumping the fuel pump relay, to see if it'll wake up, or swap it with a like relay & see if things work. If so, replace the relay, they can be had for as little as $4.50 at some parts stores.
They are such a common failure mode, many Ford folks carry a spare or two, like fuses, in the glove box LOL
I agree with chucknc, suspect the fuelpump relay, it feeds the inertia switch & it's located in the under hood main power distribution box located on the drivers side firewall.
You can try thumping the fuel pump relay, to see if it'll wake up, or swap it with a like relay & see if things work. If so, replace the relay, they can be had for as little as $4.50 at some parts stores.
They are such a common failure mode, many Ford folks carry a spare or two, like fuses, in the glove box LOL
Freshman User
Joined: Jul 2005
Posts: 31
Likes: 0
From: Everett Pa
fuel pump
hello thanks but i already but a new pump relay and that didnt help either. i also put in a new fuel pump in it too. when i turn the switch over it wont pressurize(how ever you spell it) the system, like nothing happens the pump wont kick on. i even checked all the the fuseable links and the fuse box all are good. could it be the switch is bad? or something in the wireing to the pump. btw i also put a new ignition module on it too. 
thanks myron
thanks myron
Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
Well I'd check the inertia switch, located on the passenger side fire wall, just above the carpet, about where your right foot big toe would be.
Push it's reset button & see if the pump will run.
If nothing, disconnect it's electrical connector & check for battery voltage to ground.
The power comes from the fuel pump relay, to the inertia switch, then to the fuel pump.
If you don't have power to the inertia switch for a second or two, after turning the ignition switch to run, then check the output side of the fuel pump relay for battery voltage for about 2 seconds, when you turn the ignition switch to run.
If you have power on the output side of the fuel pump relay, but not to the inerita switch, then it seems you have a open circuit between the two & you'll have to begin a wiring inspection.
Look for any place the wire rubs against something or passes through something.
Let us know what you find & we'll go from there.
Push it's reset button & see if the pump will run.
If nothing, disconnect it's electrical connector & check for battery voltage to ground.
The power comes from the fuel pump relay, to the inertia switch, then to the fuel pump.
If you don't have power to the inertia switch for a second or two, after turning the ignition switch to run, then check the output side of the fuel pump relay for battery voltage for about 2 seconds, when you turn the ignition switch to run.
If you have power on the output side of the fuel pump relay, but not to the inerita switch, then it seems you have a open circuit between the two & you'll have to begin a wiring inspection.
Look for any place the wire rubs against something or passes through something.
Let us know what you find & we'll go from there.
Junior User
Joined: Oct 2003
Posts: 56
Likes: 0
From: NC
I agree with pawpaw & Bob Ayers. The problem is definitely in the electrical signal. Print this thread and follow the wires. With any luck it won't be a worn wire (not fun).
"To test the pump itself, try jumping 12v directly to it, bypassing the relay. Then try bypassing the inertia switch. You can use a long jumper wire off the battery, if you need to..."
"To test the pump itself, try jumping 12v directly to it, bypassing the relay. Then try bypassing the inertia switch. You can use a long jumper wire off the battery, if you need to..."
Freshman User
Joined: Jul 2005
Posts: 31
Likes: 0
From: Everett Pa
hello i traced alot of wires lol. still i am not getting anywhere. my one friend was telling me it could be the pick up coil cause his was doing the same thing and the people at the ford dealer told him that was the problem. im wondering if you think that might be my problem too? hope you can help thanks guys youns are awesome.
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From: Everett Pa
hello sorry its been so long since i have responded but i have been working away 6 days a week and that wasnt letting me much free time. well i put a new pick up coil on it and that sill hasnt helped. but what i have learned is when i let the switch on the pume doesnt kick on of course but the alternator gets hot. im wondering if there could be a dead short going to that that might be causing my problems?
Freshman User
Joined: Jul 2005
Posts: 31
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From: Everett Pa
humm...... on my old fuel pump relay switch i broke the top off of it and theres a metal thing in there and when its hooked up and the switch is turned on if i push the metal thing together the fuel pump will run. also would anyone know where the pcm fuse is located at. thanks again
Thread Starter
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Postmaster
Joined: Oct 2003
Posts: 4,516
Likes: 1
From: SoCal
OK, so the problem is on the coil side of the relay. Try this, turn the key to run & see if you have 12 volts at the pump relay on the red wire. If you do, the EEC relay is good & the fuel pump relay is bad
Edit Or it could be open on the ground wire between PCM & pump relay.
Have you tried that slick trick from Rockledge for turning on the pump at the EEC-4 connector?
Edit Or it could be open on the ground wire between PCM & pump relay.
Have you tried that slick trick from Rockledge for turning on the pump at the EEC-4 connector?
Last edited by 87 XLT; Sep 20, 2005 at 07:40 PM.
Freshman User
Joined: Jul 2005
Posts: 31
Likes: 0
From: Everett Pa
well i know the pump is good because when the truck went bad i found that i wasnt getting fuel. so the first thing i did was put a new fuel pump in it. still didnt help so then i put a new eec relay on it, then a new fuel pump relay, then an ignition module, and now a new pick up coil. i have power to the interita switch i also tried by passing it but that still dont help. i know that when i put my old fuel pump relay on that i broke the top off of and push the metal thing together the pump will run, so i dont think its wireing to the pump because it runs when i push the metal together in the pump relay. so could it be that im not getting enough voltage from the battery or what? i have a digital multimeter and i checked the battery and its good. my multimeter is an innova 3320 ? when im testing voltage from point to point would i set it to the 10 meg ohm input dcv or what lol sorry but the manual didnt help me out much.
Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
Yes you set the multimeter to DC Volts & I'd use the 20 volt DC range.
DON'T use the ohms scale to measue voltage, as this could damage your meter.
It sounds like the fuel pump relay isn't getting a signal voltage to close it's operating coil, & provide operating votage to the fuel pump, so you need to look for circuit problems in front of the fuel pump relay.
There is a GEM module inside under the dash, close to the radio that provides a timing signal to turn the fuel pump relay on.
I believe it gets this signal from the computer, but the GEM times the relay to turn off after the pump runs for about two seconds, so if the GEM is misbehaving, the fuel pump relay will never see the signal to close it's contacts to run the pump before startup.
So I'd check out the GEM module next.
DON'T use the ohms scale to measue voltage, as this could damage your meter.
It sounds like the fuel pump relay isn't getting a signal voltage to close it's operating coil, & provide operating votage to the fuel pump, so you need to look for circuit problems in front of the fuel pump relay.
There is a GEM module inside under the dash, close to the radio that provides a timing signal to turn the fuel pump relay on.
I believe it gets this signal from the computer, but the GEM times the relay to turn off after the pump runs for about two seconds, so if the GEM is misbehaving, the fuel pump relay will never see the signal to close it's contacts to run the pump before startup.
So I'd check out the GEM module next.
Thread Starter
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Postmaster
Joined: Oct 2003
Posts: 4,516
Likes: 1
From: SoCal
pawpaw, i'm not sure, but I think ymtrebel has an 87 Ranger -is that correct ymtrebel?- and the wiring diagram for an 87 shows the coil side of the pump relay wired to the EEC relay & directly to pin 22 of the PCM (or ECA as the wiring diagram calls it).
Since I also own an 87 i'm glad to say that there is no GEM on it.
Since I also own an 87 i'm glad to say that there is no GEM on it.