94 Manual Ranger, Only Fires While Cranking

[LeIvoryCrow]

Bought a $500 94 2.3 manual Ranger now having some starting issues, hopefully you guys can help sort it out

-Ran ok, had a miss when I bought it.
-Adjusted timing now only runs while cranking
- while cranking I can rev the engine and it runs fine, no misses
- replaced, plugs, IAC, fuel pump, fuel filter, ignition switch, injectors, thermostat and housing (leaking).
Previous owner replaced coils, radiator, timing belt, and Icm <used>

I have power to coils key on and off,
power to injectors key on.
Cleaned all the grounds.
Maf tested good.
Relays tested good,
40 pounds fuel pressure.
Obd scanner is not reading codes <I think the connector is bad>
Will run off ether for a few seconds after switching key to run.

At one time it was running after messing with the wires under the dash. I shut it off tried restarting same issue.

Vacuum hoses could be replaced, besides that I am lost on where to check next.

Thank you for your help

 

[RonD]

Welcome to TRS

Just a heads up
1989 to 1994 Ranger 2.3l uses an ICM(ignition control module), and it only activates the Exhaust side coil pack and spark plugs while cranking, intake side starts working when engine is started(above 400rpms)

ICM was an issue when it got older, also its wiring and connectors, it can be tested at most auto parts stores

There are two power pathways for the ICM/coils from ignition switch under the steering column, one for START and one for RUN
This was a hold over from the distributor days

I would recheck power at the coil with key in RUN but wiggle the key to see if there is a dead spot that might be causing the problem
And wiggle wires under dash as well
This same 12volts from the ignition switch wire(red/light green) also powers PCM Relay

If it stays running by adding fuel manually(ether) then its most likely a PCM(computer) issue not a Spark issue
In the 1994 and earlier Rangers the PCM only controlled fuel injectors and some spark advance
The ICM(TFI or EDIS), controlled the spark and can do so without PCM even hooked up

 

[LeIvoryCrow]

Its been a busy couple days but I'm back at it, with the key on run jumping the solenoid it will not fire, spray ether in the intake and it runs. Could it be possible for a wire to be loose or corroded causing this issue? Can I test the PCM? I want to make sure it is the issue before throwing more money into this project.
Thank you for your advice so far

 

[LeIvoryCrow]

Also would it be possible to explain why it runs and revs while cranking but not in the run position?

 

[RonD]

I don't know

Best guess is that power is being turned OFF to spark or fuel or the computer when key moves back from START

There may be a starter relay on the inner fender in 1994, people often mis-wire this
There are TWO larger posts, one will have Battery Positive cable, and several other cables with it.
Other larger post should have ONLY 1 wire, ONE WIRE...........it runs to starter motor

 

[LeIvoryCrow]

I know for a fact that I have it correct, I checked it over many times. I'm going to check a few junkyards tomorrow for an PCM. I'll update once I get it in, feel free to shoot any more ideas

 

[RonD]

PCM has no connection to starting system

When you turn the key on PCM boots up and waits............
In 1994 2.3l when starter motor turns engine over the Crank sensor starts to send the ICM(spark module) a 12volt timing pulse
The ICM starts spark based on that timing
The ICM sends that timing pulse to the PCM(and Tachometer), and NOW the PCM knows you want to start the engine, so it times injector pulses with spark pulses

So there is no direct link between PCM and startup

 

[LeIvoryCrow]

I'm sorry but I am a little confused,
You are saying the PCM is most likely Not the culprit?

* The engine is not receiving fuel once the key is in the run position.

*With the key on run I jumped the starter relay causing it to turn over without firing do to lack of fuel. Therefore, something in the ignition switch or connector is causing it to cut the fuel. I have 2 ign switches, both are should be good. This points to a faulty connector? Does this sound plausible?

 

[RonD]

Yes, not PCM

You could try turning on fuel pump relay full time to take that out of the picture

Look here: https://therangerstation.com/tech_library/OBD_I.shtml

OBD connector is in the engine bay, find it, usually near fuse box in 1994
In the above link, 2nd drawing, you can see "Fuel Pump" slot on OBD connector labelled

That slot is to GROUND the fuel pump relay, like PCM does, to turn it on
So use a jumper wire in that slot to a GROUND
When you turn on the key you should hear fuel pump come on, and it will stay on until you turn the key off

 

[Ranger850]

Could the timing be off?

 

[fastpakr]

Not a timing issue.

@RonD - could this be as simple as a failing ignition switch?

 

[LeIvoryCrow]

I replaced the ignition switch earlier in my troubleshooting.
I grounded out the OBD port for the fuel pump with the key on I can hear it running continuously.
It still has the same issue runs while cranking, dies as soon as I let off the key.

 

[RonD]

So you are losing Spark or Fuel injectors when key is in RUN position

I can't remember if you did 50/50 test?
Did you try to spray fuel manually into the intake after key was back in RUN?
And did engine keep running?
If so then injectors are being turned off

If adding fuel manually doesn't keep engine running then you are losing Spark

 

[LeIvoryCrow]

I found the issue, loose wire where they pass through the firewall.

New issue, when driving the engine feels severely bogged down, no acceleration, heavy fuel consumption, and turning on the fan at idle kills the engine while driving causes a misfire.

 

[RonD]

You alternator is most likely not charging or has 2 bad fields so not charging enough.

Test battery voltage, should be 12.3v-12.8v

Start engine, battery volts should now be 14.5volts