85 Ford Ranger 2.8L Starting problems

[vanderson11]

So I recently bought an 85 Ford Ranger with the 2.8L. Im fairly new to Ford Rangers and have some questions. When i first got the truck it would crank and try to start up but wouldn't ever fire and keep running. We tried spraying started fluid in the carb but it wouldn't run off of that either. I replaced the spark plugs, Distributor rotor and cap, but still no results, now heres where it gets weird. I had a friend testing the wires that run into my ignition coil, he was testing the "hot" wire and had the wire tested grounded to the engine block, while the tester was connected i was able to fire up the truck and it ran, we removed the tester and it sat and idled fairly smoothly. After letting it run for a minute we shut it off and tried to start it without the tester, and yet again the engine would not fire. We connected the tester back up and it fired right up again. Do i just have a bad connection or short somewhere? Like i said im not very familiar with Ford Rangers, and even less with the 2.8. could it possibly be my ignition coil?

 

[RonD]

Probably missing the START wire on the coil

On older systems with single coils the coil will overheat and burn out if it runs on 13.5volts(alternator voltage) all the time.
So they have a Ballast resistor or Resistor wire that keeps the coil voltage at 7 to 9volts while engine is running.
So when key is on(RUN) there should be 8volts(approx) at coil "+"

But to start a cold engine you want Full Spark from coil so 12v(battery voltage) is used, that's the START wire

When Key is turn to START the RUN voltage is cut off, so no spark unless you have the START voltage connected.
If you are cranking and release the key engine may fire a bit, that's because RUN voltage comes back on and engine is still turning, that's a classic symptom of disconnected START wire.
Opposite is if engine starts when cranking but dies as soon as you stop cranking, classic symptom of bad ballast resistor.

The usual location of the START wire is on the Starter Relay.
It should be a 4 post relay with 2 small posts, the one labelled "I" goes to coil "+".
"S" post is for the key switch to turn on starter motor.
When starter motor is turned on the "I" post gets/sends 12v to coil.

Or there was a wire from key switch that sends 12v to coil only when key is turned to START

You can add a START wire to starter relay if you use a Diode, wire with diode connects to the larger Starter Motor post(not battery post), then connects to coil "+""
Coil only gets 12v when starter motor does, diode prevents the 8volts at the coil, when engine is running, from going to starter motor

When you hooked up the test light you gave coil 12v while cranking so it started, when you removed test light coil still had power from RUN so stayed running, but wouldn't restart because no 12v while cranking, until you gave it 12v while cranking again.

 

[komoto123]

This might help

http://www.therangerstation.com/tech_library/pdf_documents/1985_Ranger_2-8_TFI.pdf

 

[vanderson11]

I got it running today, ended up being the ignition module right in the steering column. Thanks for both the replies, both helped, much appreciated.

 

[RonD]

Good job tracking it down

Thanks for the update