Temp Gauge & Pertronix

[73Stang351C]

Am new to the forum as a registered member, and have looked through a number of posts and have not come across this one. Project is a 73 with 351C Holley 4V. I recently installed a Pertronix Ignitor after points went bad and left me stranded. Ignitor fixed the problem, but since then, my Temp Gauge doesn't work (Stays pegged at C). Grounded the wire from the sender and gauge moves to H as it should. If I remove the ignition wire from my coil (+ side), the Temp Gauge works fine (but car obviously doesn't start). When I reinstall the ignition wire to the coil, car starts, but temp gauge stays pegged at C. Been chasing it for weeks...

I've also got what appears to be a heat soak issue with my starter...Starts fine when engine is cold, but barely turns over when hot (driving for ~15 minutes or more). Read the threads on timing being a potential contributor to the problem also.

 

[73pony]

Welcome from Iowa. Can't help on the temp gauge problem as I have idiot lights. I am running a pertronix though and love it. On the start issue are you running headers and a stock style starter? If so starter may be getting over heated. I switched to a late model gear reduction starter and it solved my problem.

 

[Don C]

The temperature gauge wire and the wire to the coil are bundled together in the same harness, along with the oil pressure gauge wire. Those 3 also share a connector. I believe the two wires may be shorting together at some point in the harness or connector.

 

[midlife]

The temperature gauge wire and the wire to the coil are bundled together in the same harness, along with the oil pressure gauge wire. Those 3 also share a connector. I believe the two wires may be shorting together at some point in the harness or connector.

+1.

 

[Carolina_Mountain_Mustangs]

If a starter has lots of time on it the bearings get worn. It will gradually get slower and slower as the armature starts to drag and then quit. The extra heat also makes this worse. You might try putting new bearings in.

 

[delawarebill]

the wiring on top of intake..if it has the black plastic covering ?? open it up or remove it so u can ck the wires. they should be separate wires. if ok then look at back of engine for that plug and ck it out.

 

[73Stang351C]

So I followed that bundle and found two other new questions...See pictures below...

First is a wire/connector that came out of the three wire bundle and isn't connected to anything. Second is another single wire connector that is close to the other main connector bundle that was taped into the bundle, but the tape was loose and that wire looks like it was cut at some point and goes nowhere. Any ideas what these are for and how if they would impact the temp gauge? I'll get in and check ground/resistance/voltage later tonight.

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The temperature gauge wire and the wire to the coil are bundled together in the same harness, along with the oil pressure gauge wire. Those 3 also share a connector. I believe the two wires may be shorting together at some point in the harness or connector.

 

[Stanglover]

No idea about why the temp gauge is not working as it should cos I got idiot lights!!

The Pertronix ignitor 1, 2 or 3 should really have a direct 12 V feed from the ignition switch. Although the 1 & 2's will run on resisted current, the 3 won't and must have 12 Volts. I believe there is a relay for feeding the Pertronix from any switched 12V feed. I was unaware of this when I put a P3 on my 71 and I disconnected the pink resistor wire at the terminal block and replaced it with a 10 gauge wire directly to the + side of the coil as per instructions. This isolates it from any other wires. I don't see how you can have a short here if you put in a direct feed. Sounds like you didn't though and used the existing red wire. The short must be somewhere else, but then, why did you not have this problem with the points connected??

While on the subject of Pertronix ignitors, I just had a bad experience with a P3 that changed my mind about that product. In short do NOT use this one. Nothing wrong with the electronic module, just its piss poor construction and design for the Ford model. I'm not going to expand any more here on that, but I did switch to a P2 and solved my issues.

Perhaps you can clarify how you installed your Pertronix.

 

[Don C]

Go to the Data tab at the page and download the wiring diagram for your year and see if you can find the wires with the color codes of your unknown wiring. It's pretty common for someone to have added wires, and cut out other ones, especially that were emissions related.

 

[Stanglover]

By the way, welcome to the forum.

Electronic stuff is NOT my area of anything lollerz, but I had a thought that likely has nothing to do with the problem. Did you install a ground wire in the distributor from the movable top plate to the base/body. I know there is the black wire to the NEG side of the coil, but it also requires that separate ground. Other than that, I can see no reason for the Pertronix to have any effect on the temp gauge. ( Electrical wizards chime in!!) You could call Pertronix Tech services and run it by them. Number on their website.

It is definitely weird that the temp gauge works when the red wire is removed, but not when it's connected. Have you tried a new sending unit?

Let us know what you find and the cure,

Geoff.

 

[Don C]

That's not a bad idea. When an electrical component is missing a ground it will cause a ground loop where it seeks a ground through other components. This is pretty common and noticeable with double filament light bulbs, or when there are two bulbs in the same housing and there is a bad ground. For instance turn signals or brake lights will cause the backup lights or parking lights to come on. The ground loop takes place through the path of least resistance.

I wouldn't think this would be the case here, because the distributor and sending unit are both grounded to the block, but if the breaker plate ground wire is missing, maybe, even though it would be through the added resistance of the gauge and sending unit. I believe the current draw of the module is fairly low. I've seen stranger things happen, especially in radios and radio transmitters.

 

[Stanglover]

That's not a bad idea. When an electrical component is missing a ground it will cause a ground loop where it seeks a ground through other components. This is pretty common and noticeable with double filament light bulbs, or when there are two bulbs in the same housing and there is a bad ground. For instance turn signals or brake lights will cause the backup lights or parking lights to come on. The ground loop takes place through the path of least resistance.

I wouldn't think this would be the case here, because the distributor and sending unit are both grounded to the block, but if the breaker plate ground wire is missing, maybe, even though it would be through the added resistance of the gauge and sending unit. I believe the current draw of the module is fairly low. I've seen stranger things happen, especially in radios and radio transmitters.

I guess we'll have to wait and see what 73Stang351C comes back with. Not much else anyone can offer at this point as far as I can see. From my mega knowledge of electronics, I would guess a ground issue.

 

[73Stang351C]

Thanks for all the inputs...will work it this weekend and post how I resolved it (power of positive thinking).

 

[Don C]

That and willingness gives you a 99+% chance of solving it

 

[1mach1]

Welcome from Iowa. Can't help on the temp gauge problem as I have idiot lights. I am running a pertronix though and love it. On the start issue are you running headers and a stock style starter? If so starter may be getting over heated. I switched to a late model gear reduction starter and it solved my problem.

Big plus one on this! Changing the factory starter to a newer one is totally the way to go. It will also solve any heat soak problems you have.

 

[Stanglover]

Good luck sorting it all out. Hope our combined input helps you figure out the problems. These things can be VERY frustrating for us with some, but limited knowledge.

Geoff.

 

[73Stang351C]

Finally found time to work on it. Traced the wire bundle back to the plug near the firewall and separated the temp gauge wire from the others. Still no joy. Replaced the temp sensor and was able to get the temp gauge to move like it should. Didn't see any insulation breaks that would causing it to touch another wire, but since it operates on a ground = full scale movement, it must have been touching a live voltage wire...Which I found one in the bundle that was cut and I couldn't figure out where the other end went/was supposed to go. Taped it off to make sure it wasn't touching anything, bundled everything back up and started up...No temp gauge movement. Clearly something in that bundle I missed and will take it apart again and see what I missed. Still have a couple wires that had been cut by previous owner that I don't know what their intended purpose was. The fun continues...

 

[73Stang351C]

Traced the wiring down again, and still don't see a problem, but spliced a new wire in by tapping into each end and bypassing the bundle, and all is good. Clearly something going on inside the bundle that is hiding. Appreciate everyone's help.