This is a great forum and a lot of good info on everything.

I read two or three hours the past couple of nights on the fuel pump problems on 1994/5 F-150s. I need more info please.

I don't do too well finding things/devices on the truck so here is what I have so far and I could use some help fast.

Went to start the truck the other day and it wouldn't. This trouble just started outa the blue. Truck turns over fine but no fire, totally. Not even a sputter.

This is a 6 cyl, auto trans, 2 wheel dr. One gas tank in the rear.

I checked the valve on the fuel rail. It's dry. No pressure, no gas.
I checked the fuse in the power box under the hood on the driver side. Fuse is good.
I checked the relays in the same power box. There are five if I remember correctly. All of them are the same. Same part number on all of them. I swapped them around and still no fuel pump whir. Horn does blow.
I checked the inerita switch in the passenger side kick panel and it appears to be just find mechanically anyway.
I pulled the wiring connector at the fuel tank. There are four wires. It was dark and I was trying to hold the flashlight, volt meter, and trouble test light. The trouble test light I got a AZone uses an LED instead of incandesent blub.
Couldn't tell the wire colors exactly but with the meter I measured only 6.7 volts between the orange and brown wire. (there is a small trace color on these wires but I couldn't tell what color for sure on all of them). I measured 7.4 volts between the orange and yellow wire which had a blue trace on it I think. The trouble light lit on both. Lit up dim between the orange and brown wire and brighter between the orange and yellow wire.

I read there is a place a jumper wire can be placed to force the pump to run (if it will) by bypassing the relays, etc.

If someone can describe where to do this, if the pump will run then I want to drive the truck to this shop I have used before that specializes in automobile electrical problems and let them fix this.

Can someone describe where to do this in enough detail so an ole fogie can do it?

There was mention of a test plug and other items in the readings I did while searching the problem but I'm still at a loss finding them.

Thanks in advance for any help!

 

The test plug is under the hood on the driver side between the fuse box and firewall jumpering it to ground will supply a ground to the relay it is only used for test purposes I'm not sure if you can run it like that but it will look like this. I would check the voltage at the relays and at the inertia to see if it is dropping or if the voltage is just low

 

I will check this now and reply. Thank you!

 

The inertia switch has two wires going to it. The green/yellow seems to be the feed and it only has 6.7v on it. The red/yellow appears to be the wire out of the switch and it has 6.7v on it when it's plugged in. It has 0v when unplugged.

I checked the voltage on the four relays in the fuse box under the hood. I pulled each relay and all four had 12v on the main terminal.
Relay #2 had 6.7v on the terminal for the other side of the relay.

I grounded pin 6 on the EEC and the relays clicked just like they do when the key is turned on but the fuel pump never ran. I'd guess it still has low or no voltage at it's connector.

Looks like it's off to the shop tomorrow. Thanks again for the help!

 

Seems like if you have 12vdc going in and 6.7vdc coming out. The relay is dropping the volts, have you changed it?

 

Thanks for asking! In the original post I mentioned that the horn relay works and I swapped the relays around and it made no difference. I did not try a new relay. If it's the relay, wouldn't that mean all the same relays in the panel would be bad? Do you think a new relay should be tried? Anyway, I took it to an electrical auto shop today. I'll post what they found cause if it's something easy, it'll be an expensive lesson...

 

Oh ok.. I missed the part where you swapped the relays. Well good luck with the shop... hope it works out. Im sure we could have gotten to the bottom of it here eventually.

 

With your help I'm sure we could have...but it's the holiday season and everyone is really busy and I'm in a rush too for a fix.
And I would need a picture drawn for me for each step. Anyway, thanks for the offer of help. I'm going to post when they tell me what's wrong with it...

I was wondering if there were any fuseable links in the circuits that could have opened up.

Maybe they will call me tomorrow. Already into this for $220...65 for the tow and 155 for the initial diagnostics. Whew!

 

No fuseable link on a 94 only the fuses by the relays. On the relay with the key on you should have two terminals on the relay block with 12volts one for the relay coil and one for the pumps. Hate it's costing you so much but let us know when you find out

 

Hello,
Just wondering if you ever found the problem. I am having the same issue with my 94 f150 4.95 spd manual single tank. Please help.