Fuel Pump problems

Yes I have checked the inertia switch, where are the fuses located at under the hood, I see where the relays are and I thought that the fuses were supposed to be in the same place.

Ok, I have not had any custom work done to the truck since it has stopped working. I am getting power to the fp relay but NOT the inertia switch, I also cannot find the fuses under the hood, the haynes manual shows that they are located in the same box as the relays, but the relays are in a rectangle thing and they are the only thing located there. Since there is power getting to the relay but not the inertia switch, where does the problem have to be, I believe that mice could have chewed through a wire, but is there any way to track this down? There was a mouse nest on the engine, and it looked to be made out of the casing that goes around several wires. Also in which position is the inertia switch supposed to be in? Up or down, im guessing down, which is where I put it

There are no fuses under the hood on the 90 model. You may need to double check the power to the relay. I'll try to make this simple- unplug the relay and see if there is power on one of the two large spade terminals. If there is install a jumper wire between the two LARGE spade terminals. One of the fuel pumps should run (key off or on doesn't matter) It may be the selector switch in the dash. Let me know

One of the fuel pumps kicked on when I jumped the spades like you said. What should I do now?

With that test you made sure that the fuse link, inertia switch, selector tank switch and fuel pump are good. So now we have to find out wihy the ecm is not energizing the relay. Check the computer grounds, they come right off the negative battery cable into the body wiring harness by the battery.

Ok, so I really don't know what I am doing now, how do I check if a ground is good or not? Am I just supposed to look and see if the wire is not connected to a ground, if its split or is there actually a way to test the wire itself

Check and see if there is any corrosion right where the wire or wires go into the battery cable end. I think about 6 to 9 inches from the cable end might be a connector or two. Unplug them and look for corrosion or damage. If the is any doubt I would cut off the wires at the cable end and connector end (to get rid of the connector) and run new wires and attach them to the bolt on the negative battery cable end.

There are no connectors at the end of the cable, there is a seperate wire that comes off the the big one, it leads to a place on the body, there is a bolt sticking out of this, there are 2 other grounds connected to this one, these 2 wires run into the wiring harness( I think) the nut on the bolt looks really rusty and the part on the body where the connectors touch is kind of rusty, are these the ones you were talking about or am I crazy lol
the ground goes from the battery straight to the frame I think, this wire I am talking about comes right out of terminal connector.

I'm sorry I did mean at the terminal that hooks to the battery post, go ahead and clean those connections that the small wire goes to and any other grounds you can see. This may be the last step we can do without having a tech look at it for you. Least you know what you don't need. One more thing we can check is there should be 12v power to one of the small spade terminals at the fuel pump relay connector with key on. If there is no power to one of the terminal It could be a bad EEC relay because that where the power comes form. You can jumper across the two large spade terminals at the EEC relay like you did on the fuel pump relay connector and the truck should start if the problem is there.

Is there a SAFE way that I can run a jumper wire from a hot wire or something to get the fuel pumps working until I can figure out the problem later on?

Did you do all of the checks in my last post. Did the truck start we you had the fuel pumps running. The EEC relay is right beside the fuel pump relay.

In the last post you said to clean all the grounds, which I had done previously because of your post I figured that I had the right grounds, well the truck didnt start when I had the fuel pumps running, but it did drain the heck out of the battery when I turned it over, I think I will try to jump the battery and see if it starts, it could be flooded from the pump running for that long of time I guess?

Did you jumper the EEC relay. I did add some more info in my last post that you may no have seen

I'm sorry I did mean at the terminal that hooks to the battery post, go ahead and clean those connections that the small wire goes to and any other grounds you can see. This may be the last step we can do without having a tech look at it for you. Least you know what you don't need. One more thing we can check is there should be 12v power to one of the small spade terminals at the fuel pump relay connector with key on. If there is no power to one of the terminal It could be a bad EEC relay because that where the power comes form. You can jumper across the two large spade terminals at the EEC relay like you did on the fuel pump relay connector and the truck should start if the problem is there.

Jumping the eec made the truck run! There was 12 volts at the fuel pump relay spades, but when I ran the wire across the eec it worked fine. So do I need an eec relay?

Woohoo, thank you so much fordtech1, it was the eec relay, I called autozone and they said that that part number matched their fuel pump relay, which I had purchased previously, well I plugged back in the old fuel pump relay and put the new one on the eec and well, the truck started right up, turn the key and you can here the pumps run for a second or two, thanks a lot!

Glad to help