So, like the title says, the fuel pump won't run. I'm starting to get desperate. This is the secondary, high pressure pump located on the frame.

Was working initially. Did a massive tune up (New TFI, cap, rotor, plugs, wires, coil) and suddenly the fuel pump wouldn't hum when I turn the key to the on position.

Replace pump and it still won't run. Decided to replace the relay and it STILL won't run.

Follow diagnostic process here: Part 1 -How to Test the Ford Fuel Pump Relay (Green Relay)

Passes all of the tests except test 4. So I can get the fuel pump to run with a jumper wire, but it's not being activated by the computer. Diagnostic test to determine whether the problem is with the distributor or the computer says to check for spark off the coil. I have spark so I replace the computer.

THE FUEL PUMP STILL WON'T RUN!!!!!

HELP!!!!!

Thanks in advance.

 

You have TWO fuel pumps
Lift pump in the tank
High pressure pump in the frame rail

They BOTH run off the same wire from the inertia switch in the cab, passenger side footwell.

So first, does the in tank pump run?
You will hear it

If not then you have a power issue from the battery

Battery----30amp fuse(or fusible link)-------fuel pump relay------inertia switch----fuel pumps(with an "S")

If in tank pump runs, then you have a bad splice and/or ground on high pressure pump

Follow the wires from high pressure pump, they will go to a SPLICE, and it will be corroded, cut it out and re-splice the wires

 

I should also mention that I have checked the inertia switch, and a previous owner has already bypassed it.

I would also think it's obvious that I know there are two pumps, considering that I specifically state it's the secondary pump. I have not verified whether or not I can hear the in-tank because my concern has been "Why can I suddenly no longer hear the fuel pump when I turn the key on"

I will reiterate that the fuel pump works. I can force it to run with a jumper across 2 of the terminals on the relay. See test #3 on the article I linked. So I don't think there is a problem with the fusible link.

My local mobile mechanic wants $170 for the first hour just to diagnose, and another $85 an hour after that. So I'm turning to the forums.

 

I was not talking down to you, my posts are for general knowledge and usually cover things that original poster(you) would already know, I do this because it helps me think through things as I type, and a year from now someone who may not know why their fuel pump isn't work may see this thread and be helped by the extra explanations.
No offense was intended, just my style.

Fuel pump relay's coil gets 12volts with key on, but has no Ground so relay doesn't close
That 12volts comes from EEC relay(brown base), it also powers spark and fuel injectors, along with EEC(computer).

With key off one of the slots in Fuel pump relay base(green) will have 12volts, thats the battery power via fusible link
Turn key on
A second slot should now show 12volts, that the power from the EEC relay, if no power then either the wire from EEC relay to fuel pump relay(red wire) is bad or EEC relay or it's fusible link is bad.

If second slot does have 12volts then fuel pump relay is not being Grounded by the EEC

Relay slot image here: http://www.reuk.co.uk//OtherImages/4...tive-relay.jpg
If there is a 5th slot(below 87) ignore it

85 and 86 are the Coil connections
87 and 30 are the Load connections, 87 and 30 are connected when relay closes, these are the slots you jumped to get fuel pumps to run

So either 85 or 86 should have 12volts with key on

The other one would be the Ground wire running to the computer.
Might be a light blue wire

Red wire should be the 12volts from EEC Relay

You can add your own ground splice if that wire seems to be the problem, that will get you up and running and won't hurt anything because thats what computer does
Fuel pump will still go off with key

 

That sounds to me like you're telling me that I need to go through all the tests that are in the article I linked. Or is this something entirely different?

I can get the fuel pump to run with a jumper wire, key off, and get 40 psi on the rail. But the fuel pump won't turn off once it reaches pressure in that case (obvious, since I'm basically bypassing the relay).

All my tests say the relay is good, but it's not getting a +12V signal from the computer.

I have a yellow wire that is always hot, I jumper that with an orange/blue stripe wire to force it to run with keyou off. I have a red wire and a tan/green stripe that both go hot with key on. Pins on my relay are numbered 1-4, and I have no idea how they correlate to the diagram you linked.

I keep circling back around to thelp fact that the pump worked fine before doing the tune up, and wondering if I could have screwed something up with the new TFI module.

Any additional thoughts are appreciated.

 

Fuel pump never shuts off once engine is running, there is no pressure sensor.

On the fuel rail is a fuel pressure regulator with a Return line to the gas tank.
It has a spring and valve inside rated for 40-45psi, when pressure gets that high the spring is push in and valve allows some of that pressure to flow back to gas tank.
There is also a Vacuum Assist, it will have a vacuum line to the intake manifold.
This will help pull open the valve when vacuum is high, i.e. idling, and fuel use is low.
So running engine fuel pressure should be 30-40psi

Power for fuel pump
battery----fuse--------fuel pump relay------inertia switch--------------fuel pumps

Power and Ground to turn on fuel pump relay
battery---fuse---EEC relay------------fuel pump relay-------computer----Ground

 

What and where are the fuses you are referring to? Are they fusible links? I can't find any fuself-defense box except the one under the dash on the driver's side and there is no indication of any fuse relating to the fuel pumps there. Pics would be greatly appreciated if you have any. I'm still very new to this truck and I'm even less familiar with American vehicle engineering. Come to think of it..... this is the first American made vehicle I've ever owned, let alone needed to work on.

Also, I did find a bad ground on EEC relay. Fixed that and it now clicks when I turn the key on. The fuel pump relay still doesn't though, and I can't for the life of me figure it out.

Thanks.

 

yes, could be fuses in engine box or fusible links connected to Starter Relay on inner fender, Ford used both from 1983 to 2012 on Rangers, so no one but another 1987 Ranger owner could tell you.

But my guess would be fusible links in 1987

If one is bad you can replace it with fuses, they serve the same purpose

 

So I found the fusible links. I found 3 off of what I understand to be the starter relay. They all tested good (continuity test) so I'm not gonna change anything there.

I also tried forcing the relay to ground using a jumper wire pressed into the back of the connector, still won't work.

Any other thoughts? I'm about ready to try getting a new distributor and seeing what that does because I can't think of anything else.

 

key off
Pull out fuel pump relay and test base(green one) for 12volts, only 1 slot will have 12volts(Black/yellow wire).
From fusible link

Turn key on
A second slot should now have 12volts(red wire) from EEC Relay(Brown base) and from another fusible link

Green/yellow wire Out to inertia switch
Blue/orange wire Ground from computer to activate Relay

Wire colors change by year

 

4 images, not sure if correct order (posting from phone)

1 - key off, test light clipped to (-) post, probe yellow wire, light comes on - constant 12V confirmed, no other terminals lit.

2&3 - key on, test light clipped to (-) post, probe red and orange with green stripe - light comes on in both cases, light still on for yellow wire. Inertia switch was removed by previous owner and bypassed by tying wires together with wire nut.

4 - key on, test light clipped to (+) post, probe orange with black stripe wire, light comes on, no other terminals probed since known to be +12v for all. Confirmed that relay has ground.

Brand new relay, but I can try replacing it again, unless you have other thoughts.

If I put a jumper between the wires probed in picture 1 and picture 4, the fuel pump will come on AND give me correct fuel pressure (40PSI), but will not turn off, regardless of key on or off.

 

Then I would say your relay socket is bad

Image here of relay socket lay out: http://www.the12volt.com/12voltimages/addremacc.gif

This is a 5 pin, 4 pin won't have 87a slot

85 and 86 are the coil connections, there is no polarity, but one will have 12volts with key on, the other will go to computer pin 22, to be grounded to close relay.

slot 30 is usually the 12v from fusible link, fuel pump power, but 87 could be as well, again there is no polarity here, it is just an open or closed switch.
If 30 has 12volt all the time then 87 will be the wire to inertia switch, if 87 has 12v all the time then 30 would be wire to inertia switch.

If you put a jumper wire between 30 and 87 the fuel pump should come on, you are just doing what the relay would do when it closed, so key on or off wouldn't matter.

Lets say slot 85 is 12volt with key on
With relay plugged in, key on, if you were to ground slot 86 then relay should Click and fuel pump should start
If not then either relay is bad or base is bad

You can test relay by removing it and grounding pin 85 and giving pin 86 12v, it should click

 

Any chance you can link a video with an example or something? I tried it and can't seem to get it to work. Even tried with a brand new relay that has never been plugged in.

 

Google: How do 12volt relays work

Quick look at it

A relay has two separate parts
Load
Coil

The Coil is just that, a coil of wire around a metal rod
When you pass voltage thru this coil of wire the metal rod becomes a magnet, a magnet pulls on near by metal parts

The load is a metal bar with a hinge on one end and held up on the other end by a spring.
When coil becomes a magnet it pulls down on the metal bar against the spring, this connects that end of the metal bar to an external contact, relay is Closed

Standard 12 volt relay means Coil can use 12volts, and coil wires are connected externally to 85 and 86 pins

A relay also has an AMP rating, like 30amps, this denotes the size of the Metal Bar and contacts inside the relay, not voltage related, just AMPs it can handle without melting.
Load external contacts are 30 and 87

yes, the numbering system used sucks and makes no sense, but that is the standard.

So TWO PARTS inside that have NO connection to each other
Coil
Load

For coil to become a magnet it needs 12volts but ALSO a Ground, voltage MUST FLOW in order for coil to become a magnet.
i.e. if you hook up a 12volt light bulb to 12volts, nothing happens, no light, you also have to Ground the bulb so the 12volts can FLOW THRU the filament so it heats up and lights up.
Same with the coil in a relay

The Load is just a connection, either open or closed, 30 and 87 are either connected or they are not.

The reason relays are used is for safety.
Running 30amp wiring all over a vehicle would be dangerous, just asking for trouble from shorts.
So relays are used to keep the 30amp wiring down to a minimum, the 12volt Coil draws about .5amps, so much safer to have these wires run thru engine bay and thru firewall

 

As an engineer, I understand the basic principle of HOW a relay works. What I haven't been able to figure out is why THIS ONE won't work. If I have all the power at the correct pins, and the ground at the correct pin, why won't the coil energize? Must be bad relay. Go get a brand new relay, plug it in, coil still won't energize.

But here's something helpful finally - see attached images. Using the graphic, I was able to figure out which pins are the coil, and energize it. It works. The problem is in the wiring of the truck. Or, more likely, the layout of the relays I've been getting. As you can see, the wires for the truck are not in the correct locations to match up with the wiring of the relay. For all intents and purposes, we can assume this is an NO (normally open) relay. I DID find out that the previous relay had a sticking contact anyways, so that was another contributing factor there. Sadly, I trashed the original relay, so lord only knows what happened to it.

Image details -
#1 - pin layout for the relay
#2 - pin layout as they go into connector, in same orientation as picture 3
#3 - orientation with connector, with pins marked, and wires labeled.

As you can see, I have a ground going to pin 3, 2 switched +12V going to pins 1 and 2, and a constant +12V going to pin 4, and nothing going to pin 5.

Obviously I have 2 options. I am getting a new connector, already on its way from Rock Auto. I have 2 options for wiring it in now. I can either wire it in and match what already exists and try to find the CORRECT relay, since I've apparently gotten two now (from two different auto parts stores) that are the same but wrong for the existing wiring. OR.... I can wire it up to match the relays I've gotten.

My question for you, based on your apparent experience with these trucks..... which one will be the best course of action?

 

This is a standard 4 pin relay, all you really need: http://www.reuk.co.uk//OtherImages/4...tive-relay.jpg

And a standard 5 pin here: http://www.rowand.net/Shop/Tech/imag...iringGuide.jpg

You just don't used 87a, which would be pin 5 on your current relay

4 pin relay here: https://3.imimg.com/data3/FN/OU/MY-3...ay-250x250.jpg

5 pin relay here: https://4.imimg.com/data4/BL/NV/MY-3...ay-250x250.jpg

There is no fixed GROUND on the fuel pump relay, there is a 2 second Ground when key is turned on.
There is only 1 12v continuous
And 1 12v key on
have relay Removed when testing or you will get two wires with 12v key on, thats the Coil inside the relay it its just a coil of wire so 12v IN = 12v OUT

 

Well.... I fixed the wiring. I got 4 different relays that all behaved the same, so I decided it would be best to just changed the truck wiring to avoid further difficulties in the future. Unfortunately, the ground for the fuel pump relay is now ALWAYS a ground, so I'm assuming that means I've done something to eff up the computer. I doubt it was the rewiring. I simply cut that off one wire at a time and used my relay with the diagram as well as my Haynes manual to wire up my new relay connector correctly.

I'll try to update once I get a new computer. I just wish I hadn't sent the one back that I'd already gotten.....

 

So, things seem to be really effed up in the wiring right now. Not sure if it was something I did or not. But I've decided to get a new wiring harness off the EEC out to all of it's miscellaneous connectors.

What specs make a difference in what vehicle I can pull a wiring harness from? I know that it has to be a 1987 Ranger OR Bronco II. Beyond that, is it specific to transmission or whether or not it is 4WD?

Thanks.

 

Finally got it going. New wiring harness did the trick. Now to fix my hesitation problem....

 

Good work

Thanks for the update

 

Hi RonD,
1985 2.3 cranks, no start, spark only with eec disconnected

On FP relay test #4 with test light attached to positive and probe in relay socket wire #1, its live with key off, on and start.
With relay installed, key on, there is no power to pump?
So this wire goes to eec #22, computer controlled ground. any ideas how its grounded before key on?

 

If EEC pin 22 wire is grounded full time then relay would activate as soon as key was turned on, so problem wouldn't be no power to fuel pumps

FP Relay socket should have a 12v slot key OFF, this is from a fuse or fusible link, its the fuel pump power, always has 12volts
Key on, there should now be a 2nd slot with 12v, thats from the EEC relay for the FP relays coil

Look here: https://www.therangerstation.com/tec...ry/OBD_I.shtml

2nd drawing shows the OBD or VIP connector, usually passenger side of engine bay between firewall and Relays
Fuel Pump slot in this connector is labeled in drawing
FP slot is spliced to the EEC pin 22 wire that runs to FP relay, if you use a jumper to a ground in this slot then FP relay should "click" with key on, or with key on, FP relay should "click" when you ground that slot in OBD connector

If relay "clicks" then FP should come on

In the cab, passenger footwell, on the firewall is an Inertia switch, it has a red button on the top, it is there to cut power to fuel pumps in case of an accident
If red button has popped up then power is cut, push it back down and it should lock back down and power will be restored

FP Fuse(fusible link)--------------FP Relay---------------------inertia switch---------------------------fuel pumps

If FP relay "clicks" closed test for 12v on BOTH inertia switch terminals, so 12v IN and 12v OUT

In the dual fuel pump Rangers there is a 12volt wire splice near the high pressure pump in the frame rail, it has been known to fail, there is only one 12v wire coming from inertia switch to power both pumps

 

Ron is the MvP

 

Hey guys ,

new here but I’ve been reading up on these threads on my own troubleshooting efforts. I too have a fuel pump that won’t turn on. So far verified EEC relay and FP relay are getting power voltage. (Replaced twice with known goods )Some odd reason I can’t jumper wires 3&4 to get the fuel pump to turn on that way but can do it grounding the spliced wire coming from pin 22. I verified pin 22 has 12v and ground. I figured I would find the issue there but I’m stumped. Anyone deal with this before ? ( fuel pump connector already replaced )

 

Welcome the the forum

Fuel pump relay does use Computer pin 22 as its activation ground
Computer only Grounds FP relay for 2 seconds with Key On, but it does that each time key is turned from off to on
It won't ground pin 22 full time until engine RPMs are above 400, its a safety thing, cranking speed is 200rpm

You can ground pin 22 wire at the OBD1 connector in engine bay, look here: https://www.therangerstation.com/tec...ipped-engines/

Fuel Pump slot is labelled
That's the pin 22 wire, so if you Ground that slot then when you turn on the key the FP relay will activate full time

Ford used 2 types of relays
Mini relay seen here: https://www.gtsparkplugs.com/images/...iring-840x.jpg
Micro relay seen here: https://www.gtsparkplugs.com/images/...lay-wiring.jpg

Standard relay numbers are 30, 85, 86, 87 and 87A
Ford may use 1, 2, 3, 4, and 5 numbering, in what ever order they want, lol

But if you look at the relay base you can easily see what is what

In any case 30 and 87 will pass the 12volts to run pump
85 and 86 are used to activate the relay, to connect 30 and 87

There is no polarity, as long as 85 and 86 has 12v and a ground relay will close, doesn't matter which is which

87A may or may not be there on some relays