No Spark 1989 F-150
 

I'm using the troubleshooting guide, Chapter 5, Section 7 in a Haynes Repair Manual.

1989 Ford F-150, 302 VA with TFI-IV ignition system

Failure 1: No spark condition. All circuits check OK. Coil passes bench test. Remove distributor. ICM passes bench tests. Replace distributor to perform pick-up coil check. Truck starts during test. Truck runs for 30 seconds and stops. Pull ICM for testing and it fails 5 of 6 bench tests. Replace ICM and truck runs for 3 weeks but has occasional backfire through the carburetor.

Failure 2: No spark condition. Coil/ICM pass bench tests. Truck pick-up coil check…voltage in range when ICM module harness connector disconnected but losses voltage when connected to ICM. Disconnected the EEC-IV PCM connectors but no change in condition. Replaced ICM and truck starts but runs only 10 minutes.

Failure 3: No spark condition. Bench tested ICM and it passes. Replaced ICM. Truck momentarily fires. Truck pick-up coil check and all other checks except for stray voltage at pin 2 (TACH) of the module harness connector.

Note: This was missed on previous tests because my meter was set for whole volts. I only see
12 mille volts between the pin 2 and ground. The volts fluctuate when playing with the harness but only within 5-20 mille volts. I traced the wiring to the coil and primarily connectors and found no breaks or opens or any evidence of wear. I traced the green (pin 2) and the green coil wire until they join near the vehicle harness. There they merge into a 6-inch long shrink-wrapped device, which appears to be an inline resistor. On the other end, a red wire leaves the device and runs to one plug, and a green wire also leaves the device and runs into another plug. Continuity checks on the wires were OK.

I spoke with a GM mechanic. He said not to worry about the 12 mille volts, as it was too small to affect anything. He had me test the pick-up coil directly from the coil itself without the ICM installed. He said I should get a small amount of voltage while the engine cranks. I did, got nothing and replaced the pick-up coil. On testing I still got no voltage from the pick-up coil and engine still wouldn’t start. I assumed my GM mechanic’s advice was bogus for Ford trucks.

Any help would be appreciated.

Thanks.

Johnny

No Spark 1989 F-150
 

I have had intermittent problems from a bad ground between the TFI module and the dist. and also check the computer grounds at the negative battery terminal. It is a connecter that can be pulled apart and is known to suffer from corrosion in the connecter where you can't see it.

No Spark 1989 F-150
 

I am having a problem with no spark...and can't find the culprit. Everything checks out o.k but still no spark. It's really pissing me off.

The only advice I could really find was to check my ground from the dist. to the module. So I think I will check it tomm.

Let me know if you solve your problem...I may have the same.

thanks8D

No Spark 1989 F-150
 

>I am having a problem with no spark...and can't find the
>culprit. Everything checks out o.k but still no spark. It's
>really pissing me off.
>
>The only advice I could really find was to check my ground
>from the dist. to the module. So I think I will check it
>tomm.
>
>Let me know if you solve your problem...I may have the same.
>
>thanks8D


It's running. I replaced the ICM with a Motorcraft ICM and I begin to get a spark. I returned the 2 "bad" ICM's to Auto Zone and they refunded my money. I'll have to assume that the AZ ICMs were bad (made by Wells). I've got my fingers crossed anyway.

jk

No Spark 1989 F-150
 

Gotta love the ford TFI ignition. They are all recalled and have a class action lawsuit about them. Ignition modules would fail if they got hot or vibrated too much. I had mine fail about 3 weeks ago. I have replaced it and it runs okay now. I think with all the replacing you did, you should have considered going with an aftermarket ignition like msd. If the TFI fails again I would say get an aftermarket ignition.

No Spark 1989 F-150
 

I am having the same problem with my '89 F-150. I have 12v at the + side of the coil plug and 12v flashing on tach side. Computer, ICM, distributer and coil are all grounded. Every test I do says coil, but I put 4 used coils and 1 new coil on and still no spark. Put coil on another truck and coil works fine. I am getting very very frusterated as this is my only vehicle and now 3 weeks no go. I have 3 mechanics stummped on this one. Any advice would be greatly appretiated as I am loosing my marbles.
Desperatly Dougs4RD

1989 F-150 No Spark
 

I am having the same problem with my '89 F-150. I have 12v at the + side of the coil plug and 12v flashing on tach side. Computer, ICM, distributer and coil are all grounded. Every test I do says coil, but I put 4 used coils and 1 new coil on and still no spark. Put coil on another truck and coil works fine. I am getting very very frusterated as this is my only vehicle and now 3 weeks no go. I have 3 mechanics stummped on this one. Any advice would be greatly appretiated as I am loosing my marbles.
Desperatly Dougs4RD

Where are you checking for spark? If the the tach side is flashing, you should have spark right at the coil wire that goes to the center of the dist.

Dave F I checked spark right off the coil tip. I tried one tester (bulb type) it shows very weak spark. Then I tried strength type and no spark. I then ground a screwdriver from coil tip to bracket and nothing.. I don't know what else to try... Anyone have any tips.
Desperatly Doug S

If you take a known good coil, hook a wire from the 12 volt + of the coil to the battery +, and take another wire hooked to the battery negative/ground and touch it on and off to the coil negative, you should get a spark out of the high tension terminal. And you know from previous swapping, you do have some good coils.

I am thinking your testing method may be the trouble, but the above will make sure. When you do the test, plug the high tension center lead in the coil, and since it's going to take many hands to do the above experiment, you may just want to get a sparkplug and plug it into the coil lead and ground the outside of the sparkplug.

Coil is good tested it on another truck

I have 12v on + side of coil, and test light flashes on tach side. Could I be getting too much power on tach side, as the light does not dim much when flashing. Is it the power or the ground on tach side that makes it spark? I've changed the distributer and stator assembly.
Doug S.

When the light goes out on the neg of the coil, that side of the coil is grounded, so the circuit is complete, and power goes from the coil + through the windings, out the neg terminal, and into the module were the module electronic "switch" has grounded the neg coil wire. When this happens the coil is "charging" up. When the light comes back on, the ground has been lifted, no current is flowing, and all that "charge" in the coil collapses into the high voltage windings, and gives you the spark.

So to make a long story short, you get the spark when the light comes on on the neg of the coil.

Since your light is not getting very dim, I wonder if you have a ground problem?

See if this link is any help.

http://www.autozone.com/servlet/UiBr...3d800a185f.jsp

I'm having the same problem on my 87 F-150. I replaced the TFI module thinking that was the reason I was not getting any spark and it ran for about a day. Then a couple days later I came back and no spark again. It was the cheapest TFI module they had (like $30) so I wonder if went out again or if it's something else.

I'm also trying to remove the distributor, to check profile pickup in it. But now I can not get the distributor all the way off. I removed the main bolt at the base so now the case is free but I can't pull it off. Is there a secret? Cause my manual doesn't say so.

thanks.
Chris.