Cranking no spark

[dcpppf]

1988 2.9l 4x4 manual.

I recently did the plugs, wires, dizzy cap/rotor, and ignition coil... But I don't think any of that is the culprit.

So a couple of months back I swapped the auto trans with a mitsubishi manual. During this I put in a 4.0 clutch, fw, and starter. After driving the truck a month or month and a half I noticed it needing to start to crank a bit slower and felt like it was struggling to start a bit. Fast forward I do the plugs coil and dizzy with no change. That whole time I'm driving it every other day or so... Well I let it sit about a week and a half and went to start it last Friday and nothing.

So far I've tried charging battery as well as jumping it (I would have put money on a battery as this one is old)... Today I decided to check the ignition coil output and I got no spark in my tester. The coil resistances look good (under an ohm on one coil and north of 7k ohms on the other). It is getting a constant 12v on one terminal and the other dances on my dmm when cranking. I dont have a good tester yet to see if the pulses are 12v yet or not but it did look to be getting something.

I've read a lot about the tfi failing so I've got the special tool on the way so I can pull and test it next but figured I'd share my story in case anyone here has a good idea. Seems very suspect to me that it was a gradual decline flowed by nothing. Could the heat cycling in the tfi cause something like this or is it all or nothing? Buddy thinks maybe the hall effect sensor going bad due to weaking magnetization?

Thanks for any thoughts!

 

[gaz]

dc,

Measure the actual voltage of your battery; it should be higher than 12.65v when disconnected from the vehicle.

If not your battery, evaluate your battery terminals and wires. Both have cause these conditions for me.

If not batt or cables, verify your coil out is constant and not internmitent low.

 

[revengefizz]

1988 2.9l 4x4 manual.

I recently did the plugs, wires, dizzy cap/rotor, and ignition coil... But I don't think any of that is the culprit.

So a couple of months back I swapped the auto trans with a mitsubishi manual. During this I put in a 4.0 clutch, fw, and starter. After driving the truck a month or month and a half I noticed it needing to start to crank a bit slower and felt like it was struggling to start a bit. Fast forward I do the plugs coil and dizzy with no change. That whole time I'm driving it every other day or so... Well I let it sit about a week and a half and went to start it last Friday and nothing.

So far I've tried charging battery as well as jumping it (I would have put money on a battery as this one is old)... Today I decided to check the ignition coil output and I got no spark in my tester. The coil resistances look good (under an ohm on one coil and north of 7k ohms on the other). It is getting a constant 12v on one terminal and the other dances on my dmm when cranking. I dont have a good tester yet to see if the pulses are 12v yet or not but it did look to be getting something.

I've read a lot about the tfi failing so I've got the special tool on the way so I can pull and test it next but figured I'd share my story in case anyone here has a good idea. Seems very suspect to me that it was a gradual decline flowed by nothing. Could the heat cycling in the tfi cause something like this or is it all or nothing? Buddy thinks maybe the hall effect sensor going bad due to weaking magnetization?

Thanks for any thoughts!

I am also having the same problem but with a 2.3. the coil is sending enough power and the distributor itself is fine after testing. I'm starting to believe it's a crankshaft position sensor but looking online I can't find any for sale. Can also give me something else I should look at or show me a good link so I can order a position sensor?

 

[adsm08]

I am also having the same problem but with a 2.3. the coil is sending enough power and the distributor itself is fine after testing. I'm starting to believe it's a crankshaft position sensor but looking online I can't find any for sale. Can also give me something else I should look at or show me a good link so I can order a position sensor?

Distributor engines don't have crank sensors. A pickup in the distributor does that job and is more of a cam position sensor.

 

[revengefizz]

Distributor engines don't have crank sensors. A pickup in the distributor does that job and is more of a cam position sensor.

Okay thank you! I've been trying to figure that out for some time now

 

[dcpppf]

dc,

Measure the actual voltage of your battery; it should be higher than 12.65v when disconnected from the vehicle.

If not your battery, evaluate your battery terminals and wires. Both have cause these conditions for me.

If not batt or cables, verify your coil out is constant and not internmitent low.

Appreciate the thought here. I can definitely do that here this evening; less the coil output. How can I evaluate that though? All I've got is an in-line spark plug tester so if it was firing it'd be flashing a light, but right now it is not firing at all.

And as for the 12.65V from the battery; I figured that jumping it from another running car should eliminate the battery all together yeah?

 

[franklin2]

Appreciate the thought here. I can definitely do that here this evening; less the coil output. How can I evaluate that though? All I've got is an in-line spark plug tester so if it was firing it'd be flashing a light, but right now it is not firing at all.

And as for the 12.65V from the battery; I figured that jumping it from another running car should eliminate the battery all together yeah?

I would fix the obvious things first. If it needs a battery, get one. I know they are expensive, but you should be able to get one at a reasonable price at Walmart.

 

[dcpppf]

You're right... Last time I was in this situation I "tested" the part I thought was the problem and it tested fine... replaced that part after about 3 months of pulling my hair and all was well. Will go battery shopping while I await the TFI tool I suppose.

 

[RonD]

I would do 50/50 test just to confirm its a no spark issue

Is distributor turning?

TFI system is self contained, doesn't need engine computer for startup
Just needs 12volt and ground
BUT................there is often a 2nd pathway for 12volts when starter motor is active, it was a carry over from older spark systems
You can "hot wire" the system by applying 12volts from battery "+" to Coil "+" that will back feed to TFI
And then try to start

Wiring diagram here: https://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_Ignitionsystem_1989_2_9.JPG

The ignition switch cuts 12volt to red/green wire when key is in START and the brown/pink wire supplies the 12volts
So just to take that off the table, hot wire the system

TFI Modules did wear out, common failure point in these systems

 

[dcpppf]

thanks for the thought Ron; will give that a go tomorrow night.

Can confirm that it was not the battery. Just put a new one in to check it off the list (old one was 6 years old).

Also another note... Looking at that ignition diagram; not sure how fast it should crank but the tach bumps for the first second or so, but then drops right back to zero and doesn't budge. Looks like that could be a sign of no output from the TFI as well?

 

[RonD]

Yes, tach signal is the TFI grounding and ungrounding the Coils "-" so could be a sign the TFI, or Hall Effect sensor(inside distributor) is no longer pulsing the coils "-" so no spark
But can be 12volt fading away, lol

Generally, the starter motor can turn an engine at 200RPMs

 

[dcpppf]

Lol... welp I missed the fact that there was a plastic plug over one of the screws for the TFI module... so I just got it off haha. Worked through this test #5 measuring resistances. The only one that looked odd was the first test... Says it should be more than 60 ohms... but it measures out to be about 13,000 ohms. So WAY over. However, everything w/ the table at the bottom of the page is about spot on... so don't think the TFI module is the issue . Either way I plan to take it to O'reilly's to get tested this evening.

Maybe I'll throw a new ignition coil on it just to check it off the list... the windings measured 0.2 ohms and like 7k ohms... so both a tad under what is in the below link.

Ford EEC-IV/TFI-IV Electronic Engine Control Troubleshooting

www.therangerstation.com

 

[RonD]

depends on OHM meter but 0.5 to 0.8 would be expected, under 0.4 seems too low
Take your meter with you to the parts store and test the new one to see

There is no test for a "good" coil, you can only test for a "bad" coil, and not showing its a bad coil doesn't mean its a good coil, lol

 

[adsm08]

I do not like bench testing TFI modules, too many false passes.

Hook the whole system back up and hook a dumb test light between the battery + and the green wire at the coil, then crank it. If the light does anything but flash or glow dimly you have a TFI problem. If it never turns on, TFI problem, if it lights up bright, TFI problem.

 

[adsm08]

There is no test for a "good" coil, you can only test for a "bad" coil, and not showing its a bad coil doesn't mean its a good coil, lol

That's the screwdriver and stopwatch test. Zap yourself and time how long until you can feel your arm again.