no power to fuel pump

Hi all,

I have a 93 ford ranger that is giving me fits. When I first got this thing, the other owner had used a jumper wire to power the fuel pump. I removed that jumper and replaced the fuel relay and everything was fine for awhile. But then every once and awhile, it would just die from time to time, but it would start back up after just sitting for a minute or 2. So I figured it was the fuel filter and replaced it. But it started happening again from time to time until it finally just died and wouldn't start at all.
So I figured it has to be the fuel pump, so I replaced that with a new one. And it still won't crank. I then replaced the fuel relay again and still nothing. I then also replaced all relays, checked fuses and still nothing. I'm getting no power to the fuel pump. I checked power to the inertia switch and got nothing. So then I found a page on-line that I thought gave me a step by step approach to tracking down and testing for my missing power problem, but after a few hours/days of trying to track it down, I found out that the tests I was using only applied to a 92 and below, but not a 93.
Like I said I have replace all relays and fuses, including the EEC relay. I have power to the low side and the high side of the fuel relay but thats as far as I have gotten. I didn't want to try jumping it at the fuel relay for fear of blowing the computer because I can not find anything on-line that relates to my truck alone as far as wiring goes. I do have the wiring diagrams for my truck and a book, but since I not the smartest kid in class when it comes to electrical things, I thought I would ask here first.
So, can you guys point me in the right direction in tracking down my missing power problem.
Oh, and it will fire up with a little spray of starting fluid. So it is getting power everywhere else, just not the fuel pump. I'm starting to thing it's a computer thing but do not know how to test for that. Any help you guys can offer would be appreciated.

Quick refresher on relays
A relay has minimum of 4 pins(connections)

2 are for the coil inside the relay, this is literally a coil of wire around a metal core, when power "flows" thru this coil of wire the metal core becomes an electro-magnet which then pulls on/moves a metal bar connecting 2 other pins.
A 5 volt relay means it needs 5 volts passing thru the coil to work, a 12volt relay needs 12volts, a 24volt relay needs 24volts, ect....................
Regardless of the voltage a relays coil uses less than an amp of power

Other 2 pins on the relay are the Load connections, this will be the AMP rating of the relay, A 12v/30amp relay means it takes 12volt to activate it, and the Load pins can safely pass up to 30amps, but the relay itself only needs 1/2 amp to activate, this is why relays are popular to use, they can be located near power sources and activated remotely using smaller gauge wiring.

5th pin is common on automotive relays but is seldom used, it is also a Load pin.

Automotive relays all use the same numbering
85 and 86 are the coil connections, there is no "+" or "-" direction
30 and 87 are the Load pins, there is also no direction here, when relay is active(coil has 12v and Ground) 30 and 87 are connected, when 12v OR ground is removed 30 and 87 are disconnected.
87a is the 5th pin, when relay is "off" pins 30 and 87a are connected

The OR part is important because that is how the computer controls the fuel pump relay
When you turn the key on the Fuel Pump relay gets 12volts and a Ground from computer for 2 seconds, then the computer stops grounding the relay, it will ground relay again once engine is started, this is a safely issue.

To test relay socket(green base) make sure key is off
Test the socket for 12volts, 1 hole should have 12volts with key off, that is the pin 30 connection, it is the Fuel Pump Power from a 30amp fuse or a Fusible link connected directly to the battery, it should have 12v 24/7(all the time)
If you don't have the 12volts then fuse or fusible link is blown.

If you have the 12volts then turn on the key, you should now have a second hole with 12volts, that's the power for the coil, pin 85, it comes from the EEC relay(brown base)
So if you don't get the second 12volt hole then wiring from EEC relay or EEC relay is bad, EEC relay also powers the fuel injectors and spark system.

If you have both 12volt holes then time to test for Ground
Look at this diagram: http://www.rowand.net/Shop/Tech/images/RelayWiringGuide.jpg

Either 85 or 86 can be the 12volts with key on, so you know which one that is now.
So the other one will be the Ground connection from the computer.
Put volt meter in between 85 and 86 and turn key on, you should see voltage for 2 seconds.
If not then wire to computer or computer is bad, the computer has several ground wires it uses to control engine systems.
If there is a loose ground at the computer then that could be the problem.

This is a diagram of the pins and uses for your computer: http://www.auto-diagnostics.info/ford_eec_iv

Pins 16, 20, 40 and 60 are the Grounds the computer uses, these are grounded to body usually

Pin 22 is the Fuel Pump Ground, this pin is Grounded inside the computer to turn on the Fuel pump

thanks for the reply. I'm not going to lie, I may be over my head on this. I did run a jumper to try to power up the fuel pump the way it was when I bought this truck and it still wouldn't crank up.
I will check things out tomorrow per your post and see if I can figure anything out. Thank you for the diagrams

I went ahead and just pulled the computer just to check things out after reading so many other posts from other people with the same problem. What I found is not good. It looks like there was a small fire on the inside, and I mean an actual fire. It's burnt pretty good.
I took some pictures but can't figure out how to post them on here. So you'll have to take my word on it. I was thinking my problem may have been the capacitors like I saw in other posts from people. But I wasn't expecting that much damage. And it looks like the fire started at one of those capacitors. So I guess a new computer is in my future. Any thoughts or links as to a good company with reasonable prices would be appreciated.

The black is from leaking capacitors, yes it does look like a fire was there but probably just heat from power supplies.

If you are going to replace the computer, a 1990 to 1994 from 4.0l Ranger will work.
Computers come in automatic trans or manual trans flavors, it has to match what you have.
Also if you have an EGR system or a Cam Position sensor you need a computer from ranger with that.
2WD or 4WD don't matter

Or if computer was working except for the fuel pump relay, you can wire up that relay to just come on with the key, the computer tie in was just a safety precaution.
And you still have the inertia switch as safety backup.

Thanks for the info. But it was a fire. Scorch marks on both side of metal cover and hole burned in circuit board. And because of the way the ECM sits in the truck, other parts on the board were burnt too.
I did try to by-pass the relay by running power straight to the inertia switch and still couldn't get it to run. You are going to have to trust me on this, the circuit board it toast.
When I said earlier that it would crank with a shot of starting fluid. I just meant that the engine would hit. I didn't stand there and keep spraying. I just sprayed a little and hit the starter to see if I was getting fire to the plugs. Sorry about that.

I found a used ECM at a local junkyard. I had them open it up before buying it so I could see how things looked inside. One of the capacitors had started to leak but otherwise it was in good shape. So I went ahead and bought it and then took it to a local place to have all three capacitors replaced just to be on the safe side.
My advice to anyone experiencing problems like mine is to check the computer first instead of wasting all that money and time replacing everything else first. But to each his own.
A special thanks to RonD for sharing his thoughts with me by laying out everything in his post to address my problem.

Never seen one burn but it could happen, you have seen it first hand.

Hopefully that will solve your problem?

Yes, it is always the last part installed that fixes the problem
And hopefully it is the first part tested next time.

Here's the pictures.

Yes, I would say that was more than a leaky capacitor, that let out alot of the "magic smoke" that allows electronic parts to work.

I checked all the ground wires coming out of the ECM and all were good except for the #16 pin. In process of checking the reason why but would like some feedback on this issue.
I found out that the #16 pin/wire goes to the EDIS, and I have no idea what this is, or where it is. Here's a like to the diagram http://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_Ignition1990_4_0.JPG
Any info would be appreciated.

OK, thanks for the info on the coil pack. Why they don't just call things what they are on the diagrams is beyond me. They could at least put the common names in along with the technical names one would think.
Anyway, before I get on to testing the coil pack, can someone tell me where the ground wire for this particular object is located? I just want to make sure it's not just a burnt wire or something before I jump into it. I found good information on testing things out, so I'm good on that front.
Also, is it possible that this is the cause of my no power to the fuel pump?
Thanks in advance.
93 Ranger xtl, 4.0, RWD, standard trans

Thanks TxGasRacer, but I already read that and I didn't see anything that said anything about where or how the coilpack was grounded. Is the coilpack grounded by the engine mounting or does it have a wire that is ran to some other point on the truck? I know it has a ground wire coming out of the ecm, but when I checked it, it read no ground at that point. Does the ecm control the ground?