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Discussion Starter #1
Those of you who are familiar with my posts over the past year-and-a-half know that I've had a lot of issues with distributors. For everyone else, here's a little history.

It should be noted that all of the distributors, except the second one, have failed electrically.

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Distributor #1: I bought my '88 back in the Summer of 2013, and around December of that year I had to replace the MSD distributor that the PO put in the truck. According to his receipts it was installed about 9 months before it went bad.

Distributor #2: This was a cheap off-brand distributor that I bought to temporarily replace the MSD. It lasted about 3 months, which is when the gear on its shaft came loose. This was the only mechanical failure.

Distributor #3: This was an even exchange of the previous cheap off-brand. It stopped firing on the #4 cylinder, and only lasted 2 months.

Distributor #4: Yet another even exchange of the previous cheapo. It's PIP completely failed, and lasted about 4 months.

Distributor #5: Finally learned my lesson with the cheapos, and bought a good Summit Racing distributor. It appears that this one (after 8 months) has now died.
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Can someone tell me what the he** is going on here???

Is it safe to assume that I have some sort of electrical issue that's causing these premature electrical failures with the distributors? Personally, I've never seen anything like this happen.

Is it possible for an electrical "spike" to damage the distributor's internal PIP, but leave the ICM that's mounted to the distributor unharmed?

The only other electrical problem that I've noticed with my rig is that the test connectors don't work at all, which obviously makes troubleshooting stuff like this rather difficult. I haven't seen/heard/experienced anything else to indicate any other electrical problems.
 

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I won't beat you up over the cheap distributors as you've already figured that one out. I don't know enough about Summit branded parts to have an opinion.
It seems that whatever is killing your distributors may be upstream. Here is a somewhat generic diagram for you to look for issues:

Two areas you might look at are the 22 Ohm resistor or the aluminum shielding. I tried the cheap distributor route and ended up just having my Motorcraft unit rebuilt and haven't had a problem since. You'll have to get one from a wrecking yard to rebuild I assume
 

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Discussion Starter #3
Thanks forbye. Where exactly is the aluminum shielding located?

I'm considering a rebuilt motorcraft distributor too.
 

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I think the "Aluminum Shielding" is actually just foil wrapped around the wires.



If you search threads started by SeattleFSB and SigEpBlue they have lots of information on distributor wiring (the above pic is one of Sig's).

Let me clarify...don't buy a rebuilt Motorcraft distributor, buy an original Motorcraft distributor from a junkyard and have it rebuilt with Motorcraft parts by a reputable local shop. The "rebuilt" distributors I have fought with are usually Cardone or some other overseas company that seem to clean the unit with a file and remove so much material that they no longer fit properly. Bearings and shear pins are not usually replaced by bulk rebuilders.
 

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Check the 22K ohm resistor for sure another thing to check is the rectifier in the alternator if a few diods have gone bad it will send some AC voltage thru the system and can cause problems with frequency sensors (the MAP) and Hall effect sensors like the PIP among a few other things.
 

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Have you replaced the TFI new with the Dizzy. It is best to replace them in pairs with quality parts. I replaced the resistor in my old rig with a combo of new dizzy, TFI and got rid of this problem you are now having. The resistor was shot, offered no resistance. I went through several autozone TFI, then got a Ford unit. good luck
 

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Discussion Starter #7
forbye: I think the "Aluminum Shielding" is actually just foil wrapped around the wires.
That's what I thought, but wanted some confirmation. And those wires are part of that thicker set that's wrapped in the plastic/loom going to the TFI, etc. correct?

...And I knew what you meant about rebuilding a Motorcraft distributor.

jjandascog: Check the 22K ohm resistor for sure another thing to check is the rectifier in the alternator if a few diods have gone bad it will send some AC voltage thru the system and can cause problems with frequency sensors (the MAP) and Hall effect sensors like the PIP among a few other things.
I certainly will. The resistor and alternator's rectifier were a things that I wasn't aware of.

Swat: Have you replaced the TFI new with the Dizzy. It is best to replace them in pairs with quality parts. I replaced the resistor in my old rig with a combo of new dizzy, TFI and got rid of this problem you are now having. The resistor was shot, offered no resistance. I went through several autozone TFI, then got a Ford unit. good luck
Yep, sure have. I currently have a motorcraft tfi on the distributor. From all of the great information that all of you guys have provided, I'm probably going to end up doing pretty much what you describe, but I may go with the rebuilt motorcraft distributor instead of another new one.

Thanks fellas! And if you, or anyone else think of something additional, please do share!
 

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Discussion Starter #8
I have an additional question about the aluminum shielding. What exactly should I be looking for? Places where the shielding is torn, missing or degraded? If so, what's the best way, and best material, to repair/replace it?
 

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The shielding keeps the PIP signal from interfering with the radio as well as any outside interference from the PIP signal. Simple aluminum foil can be used to fill in the gaps where the original shielding is missing.
 

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Discussion Starter #10
Okay, this should be my last question (at least until I try these fixes).

Where can I get a replacement 22k ohm resistor?

Sorry for all of these simplistic questions. I just haven't had the time to even look under the hood yet.
 

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Okay, this should be my last question (at least until I try these fixes).

Where can I get a replacement 22k ohm resistor?

Sorry for all of these simplistic questions. I just haven't had the time to even look under the hood yet.
Radio Shack
 

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Discussion Starter #13

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Charlie don't surf..
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pic shows the 22k ohm is 0.5 watt
 

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Discussion Starter #15
pic shows the 22k ohm is 0.5 watt
Thank you, sir! I just wasn't sure if that pic showed the exact resistor I needed, or if it was just a pic of the aluminum shielding.

I tried searching for the SeattleFSB and SigEpBlue threads that forbye mentioned, but I couldn't find them.
 

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Discussion Starter #16
I finally had the opportunity to get under the hood for some diagnostics yesterday, and I am now reconsidering my initial assumption that I had another failed distributor. The truck is starting up and running just fine. And since it had been running for quite a while when it died, I'm thinking that the TFI on the distributor might be overheating and going bad.

I should also add that when I bought this latest distributor, I swapped the TFI that was on it with the Motorcraft TFI that I've been using since I replaced the MSD distributor installed by the PO.

Does it sound like I'm on the right track? AZ, Napa and other parts places can test TFI's correct?
 

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In your situation you suspect the TFI is failing when warmed up but when you have it tested it will be cold so you are gunna have to have the guy test it over and over again til it warms ups and fails, in other words... trying to duplicate the exact conditions that are under your hood.
If it were me, with the symptoms you have, I would replace it with a Motorcraft.
 

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Discussion Starter #18
In your situation you suspect the TFI is failing when warmed up but when you have it tested it will be cold so you are gunna have to have the guy test it over and over again til it warms ups and fails, in other words... trying to duplicate the exact conditions that are under your hood.
If it were me, with the symptoms you have, I would replace it with a Motorcraft.
Thanks, JScatt. The TFI in question is a Motorcraft, and I'm aware of the necessity to have the TFI test multiple time to replicate the overheating issue.

If testing shows that this Motorcraft TFI is failing, I have a couple of off-brands that I can use as temporary replacements. After which, and when I have the extra $$, I'll replace it with a new Motorcraft TFI.
 

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Discussion Starter #19
UPDATE:

I had the Motorcraft TFI tested (6 times in a row to make sure that it was holding up to the load/heat), and all tests were successful.

The truck is still starting up and running w/o issue, but speaking with a buddy of mine, he mentioned vapor lock as being a possible reason for why it died this last time around. While VL sounds plausible, my rig is EFI and (correct me if I'm wrong) I thought that vapor lock is more of an issue in carbureted engines. Right?

Regardless, and while it may not be as common, I believe that vapor lock can still occur with EFI configurations. If I'm right about that, then I want to know if this is a "rabbit hole" that I should venture into, or should I consider something else.

Even though the rig is starting and running (for now), something caused it to die, so I'd like to explore as many possibilities as I can to prevent it from happening again.
 
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