Great website! I've read through the other posts about ign problems but still can't figure out my problem. I've been working on it for the past 4 days with no luck. Here's all the details...very hopeful on gettin some help with this, as I'm getting desperate lol.

Its a '79 F-150 Explorer, 302 eng, auto trans, breakerless distributor. Up until 4 days ago, it started up fine and ran fair. It was misfiring, so I replaced the plugs, wires, dist cap, rotor, pcv valve (all brand new). When I checked the ign timing, and it was WAY off. I couldn't adjust it to even get the timing close. So I removed the distributor and followed the procedure to reinstall the distributor. Its done correctly. Since then, it has not started and I began this marathon troubleshoot.

The engine turns. I found there was no spark at the plugs. Then I found no spark from the coil. With the ign switch in the on position, I measured only 5 volts at the coil. I pulled a good coil from the junkyard and it now measures 11.25 volts (I thought it should only be around 9 volts?). I also found a newer starter relay and ign module from the same vehicle, so grabbed those up too, and installed them. My old starter relay wasn't getting voltage at the ign terminal, so I replaced with the newer unit and now have voltage. I don't know how to test an ign module. Note, the battery had a full charge throughout the troubleshoot. The ign switch tested good. I tested some of the wiring, but not methodically. I didn't find anything.

Tomorrow (Thursday March 9th), I am going to the parts store and having the IGN MODULE & BATTERY tested. Also, the battery ground cable is all ratty so I will buy a new replacement and install. If I don't find anything, where else do I look for the problem??

What about the IGN RESISTOR? Where is that located and what does it look like? Might this be the problem? I have an idea to check the wiring, methodically this time, esp between the battery-ign switch & ign switch-ign components. Thoughts, suggestions, comments ARE ALL WELCOME. I would really appreciate any help!

 

Welcome to FTE!

Follow the ignition troubleshooting procedure listed in the service manuals. If you don't you will be just chasing your tail and $hotgunning part$.

Please use regular black text without all of the fancy colors. It makes a post much easier to read. Your cooperation will be appreciated.

 

What did you set the timing too? Are you sure you got the timing right? Some set the timing thinking it is on the compression stroke.

If you pull #1 spark plug wire off the plug, then hold the wire close to the plug...What color spark do you see? Report back...

biz

 

IF you have NO SPARK, it's NOT the timing. The engine doesn't care where the timing is set to fire the coil. With that said, did you check to see that the rotor is turning while the engine is cranking? It could have sheared the gear off the distributor, or although rare snapped the timing chain.

 

+1 Torque1st post

The last time I had the same problem it ended up to be a bad pick up coil inside the dist. Without following the procedure it would have cost me a lot in plug-in-and-see parts, frustration and time.

 

Spark ?

This problem can be as simple as a a hanging by a thread or broken wire.

The coil gets it extra power from the I terminal of the starter relay.
Once engine is running... the voltage to the coil lessens.
If the battery weakens to less than 8 volts the ignition will shut down.

Until you come back with info about the ignition modulator I will hold off on other things that may cause no spark.

But,
How many miles are on this engine ?

and also :
If you never pulled the distributor body out of the engine to do any parts replacement and it was already in running condition... why would you put it out of the engine just because it wouldn't start ?

I suspect you may have a worn out timing gears & chain because this is usually the culprit in HUGE timing issues.

One bad backfire can cause a chain to shear off plastic gears and cause the timing to be 45*-60* off.

* Hindsight

You should have come here before spending all that money replacing parts that may not need it.

 

Good point EricJ.

biz

 

Dennis, in his post, he said that the engine was running. He only pulled the distributor when the timing could not be brought into spec, like it was off a tooth.

Xtreasure, I doubt that all those parts were the problem, as I can't see them all failing, but it sounds like you are checking everything out, which is good. I would pull the distributor out, and check for a gear that spins without the shaft turning. (sheared pin)

When you reinstall, just find number one cylinder at TDC of compression stroke and have the rotor point at that plug wire in the cap, with the distributor completely seated. It may take a stab or two to get it to point at the right terminal (or you can point at any terminal, and start your firing order from there when replcing the wires). A good terminal is one which will give your distributor the most range of motion, minding the position of things like the vac advance motor.

I have also had 1 pickup coil failure, but on my Tempo. With two ign modules kicking around, you should have no trouble finding a good one.

I have a feeling you are close. Double check your firing order; It may have gotten messed up when doing the dizzy r/r.

Mark

 

Thank you all for you replies, appreciate it. I initially pulled the distributor because I couldn't get the timing close. I reinstalled it exactly according to procedure and then it failed to start and I found there was no spark from the coil. QUESTION: If the problem was in the distributor, shouldn't I still get spark from the coil?

The old ignition module's connectors had crumbled into pieces so I junked it. The newer one I pulled from the junkyard tested bad. I'm going to another store to double check because the clerk's competence was questionable.

I feel confident that the firing order, battery, coil, starter relay and ign coil are good (as well as the brand new parts). QUESTION: Would a bad ign resistor cause a no start, no spark condition?

Yesterday, as I was cranking the engine, the wiring harness between the battery and ign switch burned. It was smoking quite a bit and I thought the truck was gonna ignite. I have some the interior removed to access the wiring harness. It appears to have originated at a fat red wire (8-10 gauge?) that had a thick fiber sheath. Does that make sense to anybody? I don't suppose that is the ign resistor? That wire, and all the wires around it are pretty badly damaged. To repair, should I just repair that section OR buy a new wiring harness altogether. I've been looking online, but haven't been able to locate or price it out. Anybody know how much its gonna run and where I can find one?

 

The ignition resistor wires come off the ignition switch.

The starter relay allows 12volts to the coil on Start-up ONLY

IIRC , Once the key is released from Start position and the engine is running that terminal should be dead.

The harness you mention is ther main feed to the fuse box.
It contains the fusible links and obviously have burned up doing their job
What they did is supposed to prevent fires.

Mark.
I questioned pulling the dizzy because the Engine WAS running.

He stated he could get it close enough for spec.

This leads me to believe the timing gears & chain were failing and a back fire or a simple crank the engine over can cause further stripping of the gears.



X !

You never answered my question

How many miles on this engine ?

Replacing the ingition module, Get a Motorcraft unit with a blue grommet.

 

I recommend Painless. Here is the link...
http://www.painlessperformance.com/webcatalog.asp
biz

 

Mil1ion, you misread, I could not get the timing anywhere near specs. I don't have much experience with this, but I had some notion that the previous owner incorrectly installed the distributor or timing gear. I still kinda suspect that, but have to take care of getting this badboy to start and run.

Mileage is supposedly 80,000, but I'm not sure. Thanks, this past post has been particularly helpful...

 

Quote:

Mil1ion, you misread, I could not get the timing anywhere near specs.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



No, I didn't misread this one.

You stated :
Up until 4 days ago, it started up fine and ran fair. It was misfiring, so I replaced the plugs, wires, dist cap, rotor, pcv valve (all brand new). When I checked the ign timing, and it was WAY off.

Does this mean you couldn't turn the dizzy around enough to get it closer?
What was the closest timing reading you could get ?
At this point you said you hadn't pulled the dizzy out yetwhich could cause a different setting of timing when oput back in.


My comment was that because of the mis-firing (remember the engine was running) and that can cause the plastic timing gears to be stripped and throw the timing WAY OFF.

The fact remains you pulled the dizzy on an engine that although running badly *was in fact running* before parts replacement.

So my logic says, That either something like the sparkplug wires were put on in the wrong firing order or something happened to make the timing further off.

I said eariler: Even ONE cranking of the starter with a bad timing gear can cause timing to be WAY OFF.

My point is: I'm trying to give you a reason why the timing could be way off.

To get this engine running

You need to verify:
Proper mechanical specs are made
All electrical parts are functioning
Timing gears & Chain are not corrupted

Maybe do the timing gear slop test to verify this isn't a problem?

 

Xtreasure, you will not get spark from the coil if the pickup coil in the distributor is faulty. It is that pickup coil which triggers the ign coil to spark. I went through this with my car, and replaced everything that I heard could go bad, like ign. module (installed on dist.), but nothing worked. It was that simple, dang pickup under the cap! It looked fine, but was obviously cooked. It was a pretty cheap part. Ford does not supply one for a Tempo; They only sell a complete new dizzy! Thankfully the parts store stocks em. Pretty inexpensive.

I would replace the wounded wires individually before dropping the big bucks on the harness. Try to keep the gauge of wire the same, or close as possible. If you can, change it out from source to source, instead of splicing along the length somewhere.
Keep your head when troubleshooting these things; You need it for banging on the wall later when you find the simple problem you overlooked.


Mark

 

Trinogt,

Wow. I was thinking the coil could still fire even with a malfunctioning dizzy. A light bulb just went on in my head. Just from the chronology of events, the dizzy was suspect.....the truck runs, I remove and install the dizzy, then it doesn't run anymore. I actually removed the dizzy a second time to inspect and double check the install, but didn't know how to test it. Thats why I spark tested, believing that if I had spark at the coil but not the plugs, then it would narrow it down to the wires, dist cap, rotor (which were new) or dizzy. Then when I found no spark at the coil, I only looked between the coil and battery for the problem(s). That mistake has really thrown me off, THANKS for the correction.

As for the wiring harness, I found some online. Uh...no. I'd roll the truck off a cliff before I bought a new harness. Instead, I'm gonna grab one from the junkyard for $5 per feet. Repair the harness. I'm not yet convinced the ign module is bad. Recharge the battery. Then pull the dizzy again and give a close inspection. I've seen parts for it at AutoPartsPlace.com I believe.

Oh yeah, and then go back and fix the simple problem I overlooked...

Appreciate your replies Trin!