No power to fuel pump on 4.0 ohv

[Hitchner2009]

Hey guys so i just layed in the 4.0 and hooked everything up that i could. Im swapping in the 4.0 from a 1992 Ford Ranger into a 1987 Ford Ranger that had a 2.9 with manual trans in its place. I have kept the 1987 Ford Ranger dash. Now i have power to the dash, i have lights that work and turn signals that work. horn works and everything, i also kept the 87 Ranger Headlight harness. I spliced the Red/Lt Blu wire from the 2.9 to the Pink wire from the 4.0, which im told is for the starter. This splicing was on the drivers firewall. I also spliced a Red/Lt-Grn wire from the 2.9 to the Red/Lt-Grn wire in the 4.0 which i was told powers everything in the 4.0. Now when i ran the ECM into the cab and connected it, i noticed my inertia switch connector for the 4.0 didnt connect into the inertia switch on the 2.9. my inertia switch on the 2.9 has a Pink/Blk wire and a Orange/Lt Blu wire going into the switch, and the switch on the 4.0 has a Pink/Blk wire and a Dark Green/Yellow wire. I spliced the Pink/Blk wire with the Pink/Blk wire off the 4.0, and spliced the Dark Green/Yellow wire with the Orange/Lt Blu wire so i could keep my original switch. Now when i turn the key, the fuel pump doesnt turn on, the relay clicks but the pump has no power. Im thinking something to do with the inertia switch but im not sure. Those wires i spliced are the only wires i was told i need to make the engine run and charge. So im confused. NOBODY will give me a straight anwser to the wiring, i need the wires from the 4.0 harness to the 2.9 harness that power the fuel pump, starter and main power. I can deal with everything else, but i cannot find for the life of me the wiring colors to get the power i need for it to run. I have diagrams and everything, but there is something i am missing or overlooking. PLEASE HELP! I NEED MY TRUCK RUNNING BY TOMORROW! PLEASE IM DESPERATE! THANK YOU!

 

[adsm08]

Alright, I am not sure what you actually did, but it doesn't sound right.

What I did when I did my swap was splice the inertia switch connector from the 2.9 on to the 4.0 harness so it plugged in there, then I traced the wire coming out of the switch (I think it was the orange one), followed it out across the engine bay, and connected it to the existing pink/black wire for the 87 fuel pumps.


The fuel pump isn't a starter, so I am not sure why you would go connecting a wire that you were told is for the starter to the fuel pump. Does this thing even crank?

 

[Hitchner2009]

oh yeah it cranks. i spliced in some more wires and now both fuel pumps turn on. i spliced in a pink and black wire from my high pressure pump and a red wire from my in tank pump to a pink and black wire in the 4.0 harness. the pumps turn on, but the truck wont start, its not getting fuel, i can start it with starting fluid but no fuel. idk what else there is to power the vehicle with fuel. new fuel filter and fuel pumps recently installed before the swap

 

[adsm08]

There shouldn't be a red wire to the in-tank pump. Both fuel pumps have pink/black wires coming out of the same connector at the engine bay. When I did mine I put the original 87 engine harness plug on the 4.0 harness to just plug it right in.

The HP pump will drown out the sound of the in-tank pump. The HP unit may be running but the LP one not, that will make it not run and not get fuel.

 

[Hitchner2009]

both pumps on are running on key on. i verified this by disconnecting the pink/black wire for the HP pump and left the red wire connected. The LP pump turned on, then i disconnected the red wire and left the pink/black one connected and the HP pump turns on. Theres a pink/black wire and a red wire that run down along my frame rail and they run my HP pump and my intank pump. Red wire turns on the in tank and the black/pink turns on the HP pump. I know what your saying with the black/pink for both tanks, but my in tank unit doesnt even have a black/pink wire or a pink/black wire coming from it. only my HP pump. This is a 1987 Ford Ranger. Im stumped.

 

[Hitchner2009]

we have fuel pressure at the rail but the injectors only have about 3.4 volts during cranking, that seems really low.

 

[adsm08]

Yeah, my Ranger is an 87 as well, and I've practically stripped the old girl to nut and bolts several times in the last few years.

So it cranks, it has spark, the pumps can be heard to run, so we can assume there is some fuel flow and pressure, it will run on ether.

I would check pressure, but at this point we will assume there is some.

That leaves injectors to keep it from starting on it's own. The injectors would be part of the engine harness, controlled by the computer, so their wiring should have come in with the engine. Did you plug the injector harness into the main harness?

If so, check the connection (I had fuel pump power issues caused by a loose connection, unplugged it during diag, put it back together and stuff started working, so it can still be a bad connection), then check power to the injectors, should be there key-on. If all that checks out it check the ground, should be intermittent with the engine cranking.

 

[adsm08]

we have fuel pressure at the rail but the injectors only have about 3.4 volts during cranking, that seems really low.

That is really low, it should be battery voltage. Check all of your connections for loose or corroded pins.

 

[RonD]

Fuel injectors should have 12v(battery voltage) when key is on.
Computer Grounds fuel injectors to open them.

Power for fuel injectors, and computer(EEC), coil and fuel pump relay, come from EEC relay located next to Fuel Pump relay.
Green base Fuel pump relay
Brown base EEC Relay
Black Base WOT relay(wide open throttle)

Also have a read here:
http://www.therangerstation.com/tech_library/4L_Conversion_faqs.shtml
And here:
http://www.therangerstation.com/tech_library/4L_Conversion2.shtml

Wiring diagrams here:
http://www.therangerstation.com/tech_library/EDiagrams/index.htm

Check 2.9l and 4.0l for color codes

 

[Hitchner2009]

all connectors are ok, just blew them with compressed air and added dielectric grease. I have 0 volts to the injectors with key on and like i said 3.4 volts to them when cranking. I know this is the problem with my no start now. I just need to know why i have low voltage to my injectors

 

[Hitchner2009]

i cannot find any other ground wires that could be missing. i have gone over the harness several times checking to see if thats the cause but all grounds are snug and secure. none missing.

 

[Hitchner2009]

ok so realized i wasnt testing the injectors correctly. i was probing both pins in the connector. after i probed one side of the connector for a fuel injector and hooked it up to ground i had 12.67v at key on, when cranking it lost a max of 4 volts. Oh and the truck does run for a second when you shoot starting fluid down the Throttle Body

 

[RonD]

Usually during cranking, voltage in vehicle will drop to 9.5v at most.
Your 12.67v battery voltage would indicate a fairly new battery.

You really need a NOID light to test an injector wire.

But if you have 12v then my bet is that the computer is not grounding injectors either because it is bad or it's ground is missing.
The computer has several grounds it uses for different systems.

The '92 4.0l will use Batch fire for the injectors, this means there are only two ground wires from computer to injectors, 3 injectors on each ground wire.
So 3 injectors open at the same time.


One thing, if you have the air plenum unhooked(big air tube on intake), then MAF sensor will not have any air flowing passed it so computer will not have anything to base fuel mix on.

 

[Hitchner2009]

Alright well I have work today at the shop. I'm a service Technician so I have all these tools. I won't be able to get to it until tonight. Your input is GREATLY appreciated, both of you, PLEASE stay with me on this as your help is really helping me diagnose this. I will perform these tests tonight and then give you an update once I do.

Sent from my SAMSUNG-SGH-I537 using Tapatalk

 

[RonD]

Also the Fuel Pressure Regulator(FPR) on the fuel rail may be stuck open, pressure test will tell you if it is, but remove the FPR's vacuum line, check if for fuel or fuel smell, there should be none, then suck on the line and make sure it holds vacuum.