Engine wont start, no check engine light

Thomcat · Dec 22, 2018

Hi guys
My 1994 4x4 ranger has an electrical issue. It was running fine shut it off then it wouldnt restart. Check engine light doesnt come on. Ecm relay energizes.fuel pump relay does not have signal from ecm. Jumping relay provides fuel pressure but no injectors firing. Power verified at ecm connector. Ignition fires and will start on ether. Injectors show 5 odd positive volts at both terminals (seems strange to me) I have verified ground black wire with white stripe at ecm connector.
I am thinking Ecm, but does anyone have anything else I should check?

RonD · Dec 22, 2018

Welcome to TRS

Fuel injectors should get 12volts on Red wire at each injector with key on.
Computer(ECM) Grounds the injectors to open then
So with key on engine off red wire should show 12v and tan wire or white wire should as well if it is plugged into the injector

This 12v comes from ECM Fuse(#4,30amp) and ECM Relay closing
5volts at fuel injectors means you have some low voltage
So maybe corroded wire at ECM relay

IAC Valve's red wire and MAF sensor's Red wire are also powered by ECM relay, test voltages there as well

Fuel Pump relay is grounded by the ECM but only for 2 seconds just after key on, then no ground until engine RPMs are above 400, but each time key is turn off and on ECM will ground it for 2 seconds again

1994 and older Ranger use EEC-IV ECM
There is a Connector in the engine bay that you can use to manually activate fuel pump

Second drawing down here: https://therangerstation.com/tech_library/OBD_I.shtml
Yes the VIP or OBD1 connector
Fuel Pump slot is labelled in the drawing, if you GROUND that slot then with key on the fuel pump should be on all the time, no 2 second thing
If its not the Fuel Pump relay is not getting 12volts either, which is also from the EEC relay

ECM Fuse and ECM relay power:
ECM, of course
Fuel injectors
MAF sensor, heater
IAC Valve
Fuel pump relay, coil
EVAP purge solenoid, coil
Automatic trans solenoids, coils

All use a Red wire from that ECM Relay, so check any or all for 12v key on
Swap the #4 30amp fuse with another one, or check it with OHM Meter, visual inspection doesn't work

Thomcat · Dec 22, 2018

Thanks I will check it tomorow

Thanks I willl check it tomorow

Spott · Dec 23, 2018

Are you getting any error codes from the ECM? I think you have an OBD 1 system, and you can read the codes from it with a 12v test light or analog voltmeter if needed.

RonD · Dec 23, 2018

In 1994 you can add a jumper on the OBD1 port(in engine bay) and the CEL(check engine light) will flash the 3 digit codes when you turn on the key, if there are any
111 = no codes, system OK

This is assuming the CEL bulb works, in normal use it should come on with key on and then go out after startup, or after system test.
Bulbs do burn out

Thomcat · Dec 23, 2018

Ok I lied. I didnt re read my notes. I have 12v at the injectors.
I have no check engine light at any time. The bulb is good, so is the dash harness back to the connection. I tried to use a test light in the engine bay test connector. It wont light up. I have 12 at the ecm, injectors, mass air sensor. But no firing of injectors.

Thomcat · Dec 23, 2018

I think I am showing 12 v on both sides of the injector connector because its a batch fire system and my digital meter is getting it because the the other injectors are hooked up

RonD · Dec 23, 2018

Ford injectors are only 14ohms so both wires should show 12v if injector is plugged in, there is no resistance thru the injector

CEL gets power with key on from Fuse #7, 15amp in cab fuse box, 1994, check fuse
Pin 17 on the computer Grounds CEL bulb on Boot up so it should come on at that time

I guess you should pull out the PCM(computer) and open it up
Its on drivers side of engine bay down between firewall and inner fender

What it should look like inside: http://www.auto-diagnostics.info/ford_eec_iv

The 3 Blue capacitors can leak, you will see a blackish area under and around them, this can cause system failures
Under $5 to replace them, you should replace all 3 even if only 1 leaks

Pictures here: http://support.moates.net/capacitor-repair-ford-a9l-ecm/

A9L EEC-V is for a V8 but is the same as your EEC-IV V6 as far as the Caps go

CEL is called MIL by Ford, MIL = malfunction indicator light

Pin 1 on computer should have 12v all the time, for keep alive memory
Pins 37 and 57 are Key on power, from EEC relay

Thomcat · Dec 24, 2018

Problem found. One of the caps in the ecu burned out damaging the board underneath it. What ecu's will interchange with a 94 4. 4x4?
If I have to Could I get away with one from an automatic and live with rhe check engine light, no emission inspection here.

RonD · Dec 24, 2018

The 4x4 part doesn't matter

1995 and up are different computers, 104 wire model(OBD2), 1994 and earlier are 60-wire models(OBD1)

1993/94 4.0l computer will be best bet
with or without EGR system matters as well, I think only Calif. Rangers 4.0ls had EGR

Your part number will be F47Z-12A650-???
1993 would be F37Z-12A650-???
F4= 1994
F3= 1993

7Z = Ranger or Mazda B-series(B4000 to match yours)

12A650 = Ford's part number for ANY model computer from ANY year, number is still used in 2018

The ??? after this has to do with the firmware and software that was loaded when computer was made, Ford never released info on these numbers
The will also be a larger number Stamped on the label, 3 or 4 digits, this is the final software loaded at the time vehicle was assembled at the factory, there is often a white sticker in the engine bay with this same number.
This is the important one to match if possible, this would denote 4.0l, manual/auto and egr/no egr

Look here for the Stamped code reference: http://www.fuelinjectedford.com/page17.html

As said Ford never publish any cross reference for these, this is community sharing info

If you can find a TV or electronics repair place they can swap out the 3 caps, clean circuit board and it will be as good as new

These capacitors leak because of age, 20+ years old, its only a sign of age not a indication of a problem in the computer
These computers were built to last a long time but there is no "better" type of capacitor that can be used to replace these, and they can start to leak after 20 years
So similar year used computer might be close to the same problem, "rebuilt" models will have these 3 caps replaced

Engine wont start, no check engine light

Thomcat

New Member

RonD

Official TRS AI

Thomcat

New Member

Spott

Member

RonD

Official TRS AI

Thomcat

New Member

Thomcat

New Member

RonD

Official TRS AI

Thomcat

New Member

RonD

Official TRS AI

Sponsored Ad

Sponsored Ad

Staff online

Members online

Member & Vendor Upgrades

Latest posts

Truck of The Month

Recently Featured

Follow TRS On Instagram

Latest Album Photos

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store

Sponsored Ad

Sponsored Ad

Sponsored Ad

Amazon Deals