Back story first. My brother bought this F-150 Lariat new in spring of ‘87. He kept till early 94. Put about 120,000 miles on it. He sold to painting contractor who used for 10 plus years. Somewhere in there rebuilt the motor. Painter quit using in his business and drove it occasionally. Has been sitting last five or six years. My brother tells him my dad and I are looking at buying an old Ford to fix up and drive some. My dad is 82. Painter says that if we come get it we can have it. So $40 later it’s in my back yard. A little about the truck;
4.9 in-line six
T-18 transmission, four speed with granny first gear
power windows/locks
Air conditioning
from understanding the first year EFI was used
cassette with auto reverse.....AUTO REVERSE!!!!
tachometer
no rust on body. Little Surface on frame.


what I’ve done so far;
oil/filter change
plugs and wires
fuel filter
high pressure fuel pump
in tank fuel pump
no power at pumps. Chasing that down.

 

Here is why I changed in tank fuel pump. Was no gas in tank.

 

Still no power at pumps. Testing at relays one wire showed low voltage. Started tracing wires to check grounds. Found this. Will fix later. Hope does the trick.

 

Things I know will have to be fixed;
windshield
headlights
taillights
clutch pedal nor brake pedal will depress
lots of seeping gaskets
brakes
And then whatever else shows up after repairing these things.
We have set a budget of $800 to get running with no motor issues. Does run with a little ether sprayed into intake. Into budget $275 so far.

 

Jeeze, looks like someone put a 60amp fuse in for the 20amp fuel pump wires, lol, so the wires became the fuse

 

This crank no start is about to whoop me. Not an expert and not sure I’m doing correctly, but test shows no power at fuel pumps. I’ve read everything I can to cipher it out. New relays, jump relays, test relays, bypass inertia switch, getting power to relays, just not leaving best I can tell. Sounds simple. But oh the agony.

 

Also. Check what’s in the box. Left is new relay was sold. Right is old relay. It plugged in. But finally saw it was five and not four pin. Took back and got correct four pin. But still no go.

 

Yes, you don't need 5 pin on most relay applications, but doesn't hurt anything to have it

Any vehicle with electric fuel pumps will have a cut off in case of an accident
Rangers, and most Fords with EFI, use an inertia switch to cut power

The fuel pump relay only sends power to the fuel pumps when Engine is running
It will often send power for 2 seconds ONLY with key on, to prime system, so hard to test for 12v

You can use a jumper in place of the fuel pump relay for testing

You see that there are two larger pins in the relay those are the LOAD pins, in the relays base if you put in a jumper wire in those two slots the fuel pump wiring will have 12volts all the time, this is NOT key on/off power, it full time power, from a 20 fuse or fusible link(1987)

 

Just had thought. Your comment about the big fuse and the burned fuel pump makes me wonder if previous owner had problems and bypassed all the relays and such and hot wired pumps. Next chance I get I will start at pumps and follow wires and see if I see some redneck engineering that has happened along the way.

 

While searching the crank no start problem under the dash I found this.
My theory.
these early Fords you had to jump wires in a test block with test light and count the flashes to get the CEL code. Or count the CEL flashes. Looks like some computer advanced mechanic tried to outsmart the Ford engineers. Weird part is they had two leads connected to two key on fuses. The joys of trying to get into someone else’s head and figure out what they have done.


The yellow things are fuses. One was burnt up.


Had plenty of cord to hook to a computer outside of truck. Cord was hidden behind passenger kick plate.

Googled these numbers and nothing came up.

 

Back to basics. Why isn’t fuel relay working? It has 12v from battery. But not 12v on other side. Supposed to come when ignition is on. Only has 5.08v. And not supposed to have that. Either 12 or zero. Little thinking outside of box. The eec relay has the 12v on both sides like supposed to. The eec is supposed to send 12v to fuel pump relay, then to the pumps. I jumped the 12v key on wire from eec relay to the 12v key on wire on fuel pump relay and now have power at the tank and rail pumps. Tomorrow will hook has back up and see if cranks.
now the question is why am I not getting the 12v to fuel pump relay. The eec relay tests good.

 

Not following completely

Relays have 2 separate circuits

12v---------coil-------------ground<<< this activates the relay, coil becomes a magnet

12v--------relay bar--------Device(fuel pump)<<<gets 12v when "bar" is pulled down by the coil being activated

The two 12v's, in the case of the fuel pump relay, are separate, the coil's 12v comes from EEC relay
The 12v for fuel pump comes from a 20amp fuse or fusible link
The device wire runs to inertia switch usually, and this wire will have 5 to 8volts with key on, its from a monitor circuit so that normal, 5-8v has no amps, just volts, so can't run fuel pump, when fuel pump relay activates then it would show 12v and have amps

And the Coils Ground comes from the computer, computer controls fuel pump relay

 

I’m sure I wasn’t explaining properly. But makes sense in my head...


This is fuel pump relay. Wire four is constant hot and tested 12v. Wire two should be 12v with key on. Was only getting 5v.


This is eec relay. Wire four is constant hot and tested 12v. Wire two is 12v with key on. I took wire two from eec and put to wire two of fuel pump relay and both fuel pumps have 12v.
not exactly sure what I did, know I probably shouldn’t have , but didn’t know what else to try. The problem is why is wire two of fuel pump relay only getting 5v. That’s the million dollar question.

 

1 and 2 on both are the relays coils, so one is 12v the other a ground when relay is activated

3 and 4 are the Load wires, when the relay's coil is activated 3 and 4 are connected together

The red wire on EEC relay sends the 12v from the yellow wires out when EEC relay is activated, to the Fuel Pump relays red wire, but...............

The EEC red wire runs to a Splice, with maybe 7 other Red wires, this powers: injectors, EEC(computer) x 2, fuel pump relay, EGR solenoid, EVAP solenoid, plus a few other devices

So the splice is probably where your voltage loss is coming from, corroded maybe
Test any one of a fuel injectors red wires if its 5v then yes splice is the issue

This is a 1991 diagram but red wires are correct for what you have

 

Had a little time today. The fuseable link I changed first didn’t have good connection. My doings there. Fixed that. And now have 12 volt to front tank plug (the one I took burnt pump out of) and high pressure pump. But nothing comes out of tank and high pressure will click a couple times, won’t run. So I’m thinking bad ground somewhere. The front tank grounds go to high pressure and also to back tank. I haven’t done anything with back tank. Grounds from front tank to under the hood seem all intact. So I’m going to go to back tank now and check wiring.
Something for nothing is usually what you get...... but I’m gonna whoop it before it whoops me I hope.

 

Question. The new in tank pump, I took out, hooked to battery. Could hear it click, but couldn’t hear it run and not sure I could even feel it working. It is a low pressure pump. Should I have been able to be hear and feel it working?

 

Yes, its an electric motor, not sure why it would make a "click" noise?

 

Took both pumps back. Walked in with alligator clips and asked them to test them for me. Both would click and no hum, whiz, or whatever describes them when running. Got one new one and I asked them to test it. It is working. Other here tomorrow. I could have done something to break them. But always unhooked battery when I would do any kind of work. Like you say, “new only means untested”.

 

I doubt you could do something to break them "electrically", with a hammer all bets are off, lol

So they were bad out of the box

Batteries just have the 12-13volts
Running engine/alternator with bad voltage regulator can send out over 15volts which can damage electrical parts

 

Got to new fuel pumps. And......it runs.
will change injectors.
opinions on sea foam and other magical cleaners?
tried to upload a video from phone. Either operator error or can’t.
no knocks, pings, smoke, bad smells.

 

Have to pump the gas and keep it around 2500 rpm to keep running. Will change fuel pressure regulator tomorrow If time. And then there’s vacuum lines.

 

Good stuff :)

Seafoam does work for my fuel injected vehicles, use it once a year and really cleans up idles, less skipping, after 1/2 tank or so

Double check firing order, easy to reverse a wire or 3, lol

 

Trying the video. Unless previous owner mixed wires, I changed them one at the time.

 

Well free to check and it don't take long on a straight 6
Chasing your tail trying to fix what are reversed spark wiring takes HOURS of time, lol, "been there, done that, have the T-shirt", well several of them, because I never learn, lol

I have also spent a hour or two diagnosing vehicles that are OUT OF GAS, yes, out of gas, you would think someone would learn from the first time, NEVER BELIEVE the owner...................

4.9l firing order: https://ww2-secure.justanswer.com/up...ring_order.jpg

 

Had very little time today. Crunk the truck. I kept it at 2500-3000rpm and it seemed to run fine. Like it wasn’t starved for gas. But won’t idle. My thinking is to check the parts like MAP, idle control, fuel regulator, and vacuum hoses.
And the firing order. Agree?