1987 Ford Ranger 2.9 No Spark

[wollnutz]

This is my second post on this Ranger. I recently did a bunch of work to my 87 Ranger and it has been great for a few months, but yesterday I stalled and couldn't get it started in a parking lot. I sprayed starter fluid in the intake and still the engine just turned without firing, so I am assuming it must be spark.. Previously it would not start due to no pulsating ground to injectors, which was fixed by a new ECM computer module. Since the computer module was replaced so was the ignition module, relays and relay connectors, spark plugs, ignition timing done, and most recently- the ignition coil.

After I got stuck in the parking lot I messed around with it for about an hour, but nothing seemed to work (including starting fluid). Then randomly it fired back up and got me about 4 miles to home. Today I got it running and made it about a half mile and it actually stalled while going about 20 mph and now refuses to start. While it was running during that half mile it was completely fine running like normal. I replaced the ignition coil right there on the side of the road, but it didn't make a difference.

Any ideas?

 

[RonD]

Get a volt meter and check Coil "+" terminal with key on and also while cranking, it should, of course, have power in both key positions.

Power for spark system comes from ignition switch, under steering column, and for START position it also runs thru a Clutch IN switch(manual) or PARK/Neutral switch(auto)

TFI testing info here: http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

Just as a heads up for how the system works because it may be related to your previous problem.

The TFI module on the side of the distributor gets a timing pulse from the sensor inside the distributor that reads a toothed wheel on the shaft as distributor spins.
That timing pulse is called the PIP((profile ignition pickup), TFI module starts and times spark based on that timing pulse.
The TFI sends that PIP pulse to Computer(ECU) so it can time the fuel injectors, without PIP pulse coming in ECU doesn't even know you are trying to start the engine, it just thinks you are sitting there with the key on.
So no injector ground pulses without PIP

SPOUT(spark out) is the timing signal sent back from ECU to TFI module, it is not needed for spark to work but is needed for engine to run at higher RPMs, it is the "vacuum advance and mechanical advance" for the TFI system, ECU is used to calculate that.

Because of the previous problem and now current problem, it looks more like a wiring issue than a part issue.

In the above link click on TFI work sheet and follow the tests
Also wiggle the wires WHILE TESTING voltages, past and present issue could be wiring related, 30 year old wires can get funky

 

[rhythim]

^this. Mine did it the other day, coasted into a parking lot. Wound up being a break in the (age and heat-hardened) insulation on one of the wires in the harness that goes to the TFI module, was grounding itself to the distributor. I taped it up for the roadside repair and am now replacing that whole section of the harness a wire at a time with a soldering gun and heat shrink.

 

[jonathan62019]

Grab the end of a sparkplug wire and have someone turn it over. If you scream in pain. You have spark.

 

[Pauls 4x4]

Check the cap and rotor, wires, etc. Make sure the coil fires strong. Basics first. But it eliminates a lot of culprits to do those things.

Right now it's pretty open ended.

 

[wollnutz]

Just tested voltage on coil. 12 volts in run position, but it drops down to 9 volts when cranking.

 

[RonD]

9 Volts is OK when cranking, a little low but battery may be older.
Starter motors pull alot of AMPS from battery, which is why the cables are so big

Good battery is about 12.5volts, you can get up to a 3volt drop when starter motor is turning engine, so 9.5volts.
When battery gets down to 12.2 volts, or less, its time to shop for a new battery, next cold morning will cause a slow crank, and click, click, click

Did you wiggle the wires around while testing voltages with key on(RUN)?
Don't be gentle, an intermittent or bad wire needs to be found while you can fix it, not on the side of the road or in a parking lot some where

 

[wollnutz]

9 Volts is OK when cranking, a little low but battery may be older.
Starter motors pull alot of AMPS from battery, which is why the cables are so big

Good battery is about 12.5volts, you can get up to a 3volt drop when starter motor is turning engine, so 9.5volts.
When battery gets down to 12.2 volts, or less, its time to shop for a new battery, next cold morning will cause a slow crank, and click, click, click

Did you wiggle the wires around while testing voltages with key on(RUN)?
Don't be gentle, an intermittent or bad wire needs to be found while you can fix it, not on the side of the road or in a parking lot some where

Battery is only a few months old. I didn't notice any fluctuation when moving wires but I didn't get very far with it today either. I have all of tomorrow to mess with it more.

 

[wollnutz]

Forgot to mention since I got the truck I often stall when shifting into reverse unless I hit the gas pedal right away and keep it revving. It was always fine in other gears, but has stalled in park several times.

 

[RonD]

Clean the IAC(idle air control) Valve
The IAC valve is the "idle screw" on fuel injected engines.

The automatic transmission has an NSS(neutral safety switch) that tells the computer when trans is in Park/Neutral and when it is NOT in Park/Neutral.
When it is NOT in Park/Neutral then computer will bump up the idle(open IAC Valve a bit more) because trans is "in gear".
Computer monitors RPMs via the PIP signal(spark timing signal) from the TFI module, thats also how it times the fuel injectors, so PIP signal is at the computer or you would have a no start, no injectors.
Computer has "target" RPMs in memory, for cold engine-1,100 to 1,300rpm, and warm engine-700 to 800rpm
It uses the IAC valve to set those RPMs

So best guess would be to clean the IAC Valve.
While IAC Valve is off plug in its wires and turn key on, IAC Valve should open all the way, then unplug its wires and it should close, repeat a few times to make sure it is moving freely and all the way.

 

[wollnutz]

Clean the IAC(idle air control) Valve
The IAC valve is the "idle screw" on fuel injected engines.

The automatic transmission has an NSS(neutral safety switch) that tells the computer when trans is in Park/Neutral and when it is NOT in Park/Neutral.
When it is NOT in Park/Neutral then computer will bump up the idle(open IAC Valve a bit more) because trans is "in gear".
Computer monitors RPMs via the PIP signal(spark timing signal) from the TFI module, thats also how it times the fuel injectors, so PIP signal is at the computer or you would have a no start, no injectors.
Computer has "target" RPMs in memory, for cold engine-1,100 to 1,300rpm, and warm engine-700 to 800rpm
It uses the IAC valve to set those RPMs

So best guess would be to clean the IAC Valve.
While IAC Valve is off plug in its wires and turn key on, IAC Valve should open all the way, then unplug its wires and it should close, repeat a few times to make sure it is moving freely and all the way.

I took the IAC valve off. It was full of sludge. After removing it I took the 2 screws out that separate the two pieces. By looking at it through the 2 open holes I'm not really even sure how it's supposed to work. The center shaft moves up and down but I don't see anything actually happening. And I'm assuming the piece with the plug is supposed to push out when key is turned to run position? Because when I did that it did not move. If this part is bad it will cause a no start issue?

 

[RonD]

The valve lets air flow into to the intake manifold when throttle plate is closed.
One "hole" is on the front side of throttle plate, the other "hole" is on the back side of throttle plate.
The IAC "motor" turns and valve slides in and out, it is a 12volt electric motor, with a spring return, when you turn on the key the computer gives it 12volts so it will open all the way, to partially close it the computer pulses the 12volts.

Yes, with less air engine won't start, try push down a bit on gas pedal to let in more air for starting.