What pins should I contact and what voltages should I be see?

Want to make sure it's not electrical before I replace the fuel pump assembly.

Bonus question: How can I clean off the old grease and what should I replace it with?

 

The Pink/black(12v) and solid Black(ground) are the larger wires and for the fuel pump
They will only show 12v for 2 seconds each time key is turned from off to on, no constant 12v until engine RPMs are above 400
But after the 2 seconds you might see 5-8v, that's from a Monitor system in the computer, no amps, just volts

The yellow/white(fuel gauge) and black/yellow(ground) are for the Fuel level sender/float inside the tank, just FYI


Its called Dielectric grease, it doesn't conduct electricity so its safe to use inside connectors, won't short them out
But avoid putting it on the metal pins and slots BECAUSE it doesn't conduct electricity, lol
Its there to prevent moisture intrusion inside exposed connectors, so just needs to be on the outside edges

 

Okay I saw a steady ~6.5v from the two larger ones on the left in the image.
The other two were around ~11.5v

I can't get the fuel pump to turn on and I have new one on order.

I checked the bypass on the passenger side, it's good (but now unplugged to remove pressure from the fuel lines)

The only other thing I can think of is the fuel pressure regulator and I don't know how to check if that's good

Thanks for the help!

 

Ford fuel pumps are NOT quiet
If you don't hear it with key on for those 2 seconds its not working

FPR would usually leak fuel if its broken, cause rich running, but engine would always start

 

Yeah, when it would come on I can hear it in the cab with the windows up.
It's dead now, last ran a week ago.

I have it all prepped to swap and that part is coming in before the weekend.

Might be hearing back from me soon :D

 

A new fuel pump did not fix the problem. It was quite an easy swap, but once everything was connected, I still cannot hear the fuel pump fire.

I swapped the relay and that is fine
I am seeing about 6.8v on the left two wires and almost 12 on the other two to the harness plugged right into the pump (key on)

What could be wrong?

 

I got it started, but not sure if I've solved any problems. I think I have one or more bad relays.

I moved the PWC, PWC Diode, and FP relay around

For awhile, ODB was powered but would not talk to ECU while powered on.

In some configurations, I get 0 volts at the FP.

I tried tapping around the relays, thought I heard some clickings.

Tried swapping them for awhile, cant figure out which one is bad.

Pulled one from the ABS and tried to crank it.

I NEVER heard the new fuel pump, but it started. Cranked a few times over changes relays, but this time it started.


Not sure if I've solved anything, or just luck right now.

Any advice?

 

One final update

Went for a drive around the block

Turning in the blinkers I can hear a buzz noise (left or right) in the dash and the blinker light is dim.

Defiantly dealing with an electrical problem.

Any advice is welcome.

 

Ford uses 2 kinds of relays, Micro and Mini

Micro base seen here: https://www.gtsparkplugs.com/images/...lay-wiring.jpg

Mini base seen here: https://www.gtsparkplugs.com/images/...iring-840x.jpg

All relays use the same numbers for the same functions
30 and 87 are the contacts for the "load", the 30 or 40amp rating,, one will have 12volts, they other slot is connected to "the device" that needs power, in this case the fuel pump
Doesn't matter which slot is which, 12v or device
Usually 30 or 87 will have full time 12volts, key on or off doesn't matter

85 and 86 are the relay's Coil, use to activate the relay, one will be 12v and the other a ground, again doesn't matter which is which

Usually relay coil's will get 12v with key on, but NO ground, the ground is used to turn relay off and on, to connect 30 and 87 together(ON) or separate them(OFF)


87a, this is called 5 pin relay, most relays are 4 pin, no 87a
In some setup you may want to power two different things using the same relay/fuse but do not want BOTH devices to be on at the same time
Say Fog Lights and Headlights, if its foggy the white headlights are too high and reflect off the fog too much, "white out", lol, then lower yellow fog lights are needed, you can activate Fog lights which turns off the headlights, with the one relay
In this case 30 would have to be the 12volt power for the lights
When relay is off 30 and 87a(headlights) are connected together, head lights on, when relay is on then 30 and 87(fog lights) are connected together, fog lights on

Anyway you know what to test for now, what slots are for what

Yes, if your exterior lights are also having issues then most likely cause is negative battery cable, grounding issue
Larger ground cable goes to engine, usually starter motor bolt, grounds starter and alternator

Then a ground from top rear of engine to firewall, usually back of drivers side head to wiper motor bolt, main cab ground, also computer

Then a smaller wire from battery negative to Rad support and inner fender, grounds for headlights, park turn and horn

Then a ground from engine to frame, for tail lights and maybe fuel pump and fuel level sender
Engine and trans sit on Rubber mounts, so not a good ground to frame, lol need a ground wire

Grounds are often over looked, but are exactly the same as the positive wiring, if a positive wire can carry 10amps but ground wire can only carry 1 amp, then 1 amp is the limit for that circuit
So a loose, missing or corroded ground wire is exactly the same as a loose, missing or corrode positive wire, exactly the same

 

Looks like all the ones I have pulled at mini's.

I'm reading less than about 5.6 to 7.6 ohms of resistance across pins 85 to 86 on all of them.

Does this sound right? Resources online say this should be in the 70's.

As for the buzzing blinker. I realized I still have the bed off and the back lights are disconnected. Maybe that is causing the blinkers issue?

 

Check your OHMS scale, should be at 200, so you are actually reading 56-76 ohms which is fine, relay's coil is literally a coil of wire, so little resistance

 

I found a bad relay. It wouldn't open (or is stuck open) with 12v applied to it.

Also certain I'm dealing with more electrical issues.

I unhooked (not disconnected) the relay fuse box. With key on and some shakes, I can hear it click on and the truck will start. I can shift it around, and it might not start.

 

Yes, reads like some corrosion inside the fuse box

 

I am reading about 11.5v for FP and PWC relay in the fuse box. Bat is putting out 12v.

Is this acceptable or possibly part of the problem?

I disconnected all the grounds, cleaned and polished them up. None looked too bad.

Once the relays click in, it fires up no problem.

 

Good battery is 12.3v to 12.8v
Brand new battery might be 13.0v
3 year old battery is 12.5v
5/6 year old battery 12.3v and time to shop for battery sales

Why 12.2v and lower can cause issues
Your starter motor will draw high amps all at once, if battery voltage drops below 9.8v or so while cranking spark gets very weak and electrics can "brown out" and reset
Starter can drop voltage 2.5volts while cranking
12.3v - 2.5v = 9.8v

But 12.0v down to 11.5v might be OK with weak battery and key ON, if key was off then its too much of a voltage drop
With key on several systems are now drawing amps/voltage from battery
So with key on test battery voltage first, thats you base line for Key On voltage tests to see if there is too much of a voltage drop, over 0.2 would be too much

 

That's my fault, I've been cranking on it for awhile. I put a trickle charge on it and it's 12.3 and raising

It's about 3 years old.

 

So far, she's running OK. However, having issues with ABS sensor. I replaced it with a new one but discovered I am getting about 9.6v and 0.5v (truck running) on the ABS pump and ABS main relays.

Obviously something still going on with the wiring.