FYI FORD MustangSteve's Ford Mustang Forum / Pertronix and their coil fail??

**Posted by Cab4word67** 6/30/2024 4:59 PM

Heres what happened on a 1/4 mile drive. This is a 2 year old points conversion #1281 with the 1.5 ohm 40K coil. been doing well since 2022 ,not that long. pulled out of garage and car died while door was closing on garage, started up and went to store. Wouldnt start for over 5 minutes at store, just crank over. Then made it almost out of the parking lot same thing it died. 5 minutes later it started and I went down street a couple blocks and it died again. took about 15 minutes to start this time and I had help so I tried to check spark,Not sure if I had spark the first try or if it was me testing but second try it started. Shut it off put plug wire on and it started so I got it home. Today I checked everything I could. I have 1.3ohms at the coil says its a 1.5 ohm coil, 11.5 vots to the coil, .030 gap on the ignitor, battery 12.1v 14.3 when running.
I have read that they work or they dont only. Some say my coil is going out. I tested it again when it was hot with same numbers.
I reinstalled my pionts with a balast resistor to see if it does it again, if it does I have another coil witch would tell me then it is the coil. A cople time while idleing around town the motor will shut off for a 1/2 second witch has always made me wonder??but it contiues to keep going after the little glitch. I am pretty sure it has fuel as in checking i could see the little smoke trail come out of the ports of the sniper like fuel had entered the intake
Im stumped it just went 8K on the road trip WTH

Last edited by Cab4word67 (6/30/2024 5:02 PM)

**Posted by 6sally6** 6/30/2024 5:16 PM

Mustang "pony;s-leg" are getting cramps from such short trips after the 8 grand one ?!! Drive it down to San Diego everyother week to keep it 'loosened-up'.......
I can't help I installed a 'care-free' duraspark distrib with MSD box a number of years ago.......
6sal6

**Posted by rpm** 6/30/2024 7:34 PM

First question, are you providing a constant 12v to the coil? Ya gotta bypass the pink resistor wire.

**Posted by GPatrick** 6/30/2024 7:55 PM

If you hook up the Pertronix again it is fairly easy to see if you have a coil failure or a sensor failure in a Sniper datalog. If it acts up start a log. If the RPM in the log drops abruptly, the sensor is failing. If the RPM slowly drifts down until a stall, the coil has failed. Another test that is easy if it won't start is to look at the handheld/TSLCD display and crank the engine. If it continues to display "stall" the pickup/sensor has failed. If it shows RPM, the sensor is working and the coil is not. I had a Pertronix coil fail on my truck when I was running an ignitor distributor before moving to timing control. It ran fine and the next time I tried to start it, it just cranked. In this case, while checking for connections I touched the coil and it was extremely hot. Later I checked resistance and it checked OK when it had cooled down. I had a spare, swapped it, and I was back in business.

**Posted by Cab4word67** 6/30/2024 10:45 PM

RPM Bob yes I have cut out that wire, that is why I had to add the resistor block when I put the points back in. Thanks

**Posted by Cab4word67** 6/30/2024 10:48 PM

Thank you GPatrick that is info I needed.

**Posted by TKOPerformance** 7/01/2024 4:59 AM

I had my first Ignitor fail because I didn't realize I couldn't leave the key on for extended periods of time without damaging it. I was testing some electrical stuff in the car and should have unplugged the Ignitor, but didn't. The car started up fine and drove to the gas station (3 miles away) after I got gas it would not restart. I know some of the ;later Ignitor variants have protection for that type of failure built in, but not sure which model you have. When I pulled the failed one it was pretty obvious heat had gotten to it. Just something else to look at.

**Posted by BobE** 7/01/2024 7:09 AM

First thing to realize that intermittent problems can be a bear to resolve.
You tested the primary side of the coil, the secondary side (+ terminal to center tap) should be about 10,000 ohms. I’ll email you a "how to test" an ignition coil.
Check all your wiring to the coil to ensure good connections. You may want to try jumping +12v from the battery terminal on the starter solenoid to the + terminal on the coil. If it starts, there is an issue with the wiring between the ignition switch, and/or the starter solenoid. Remember, when starting the engine, a wire on the starter solenoid is providing full +12v to the coil.
That resistor block you installed could be intermittent, jumping around it would tell.
If you have a coil to replace just for a test would be good to try.

**Posted by wsinsle** 7/01/2024 9:35 AM

You could put a jumper from the battery to the coil when running. This will let you know if you have a bad connection going to the coil maybe heating up when running. Will have to remove the jumper to shut off the car.

**Posted by Cab4word67** 7/02/2024 7:03 PM

I mite have located the varmit. I reinstalled my fuel pressure gauge just to make sure this isint fuel related. Car started and backed ot of garage there it sat all day. Went to start and no fire just crank. Hand held says rpm, but after 4 trys I went out while key was on and fuel is at ZERO. Now I have to figure out why no fuel with a new pump. Also i need to figure out what signels the fuel pump relay and maybe install a bypass switch.

Last edited by Cab4word67 (7/02/2024 8:03 PM)

**Posted by GPatrick** 7/02/2024 7:37 PM

The fuel pump prime runs for 5 seconds and the pump stops until the system sees RPM. This is a safety measure to ensure that the pump shuts off from a stall or accident. Depending on your fuel pump the pressure can drop quickly if there is not a check valve. You need to check pressure when it is running, not sitting. You can have a helper turn on the key and you can confirm pressure during the fuel pump prime. You can also check to see how quickly the pressure drops when the prime stops. Note that if you crank it several times without turning off the ignition the pump will not prime again and the cranking fuel will quickly drain the pressure. There have been some cases of a faulty fuel pump relay so you may want to reseat it and confirm that it is working consistently.

To clarify the pump will not turn back on until the ECU sees the crank to run RPM (usually 400) has been exceeded. During cranking it is relying on the residual pressure after the prime. If the ignition is not turned off and back on, there probably won't be any fuel pressure.

Last edited by GPatrick (7/02/2024 7:42 PM)

**Posted by TKOPerformance** 7/03/2024 5:24 AM

Is there an inertia switch in the system? I've seen them get jostled and turn off causing the fuel pump not to run.

**Posted by BobE** 7/03/2024 6:32 AM

GPatrick – Just an FYI, I have the MSD Atomic 2 EFI system. I have a relief valve installed that maintains about 60psi, and I installed an inertia switch (not included with the Atomic 2 system). The Atomic 2 system does not shut off the pump at a high pressure.

**Posted by GPatrick** 7/03/2024 8:54 AM

The Sniper uses an internal or external fuel pressure regulator so pump pressure should be limited to the regulator setting. It doesn't shut off fuel at high pressure. The activation of the pump with the exception of the initial prime is based on RPM and the "crank to run" RPM. There is no reason an inertia switch could not be incorporated into the Sniper's fuel pump relay trigger wire or the main pump wire. Unfortunately the Sniper does not sense/monitor fuel pressure (the Super Sniper can) so it can be tough to diagnose fuel pump problems, clogged filters, or blocked or open regulators.

There is a small blue wire that provides a ground trigger to the fuel pump relay. The large blue wire feeds the pump. A bypass could be incorporated using the ground trigger. This would allow the pump to be activated when the ignition is turned on but in the interest of safety I'm not sure I would recommend this.

**Posted by Cab4word67** 7/03/2024 10:25 AM

Just got off the phone with Holley tech. He said I can go into the computor (not the handheld) and change the 5 sec time outout to any time i want or just cut the triger wire off the relay and put it to ground like they do on race cars.

**Posted by GPatrick** 7/03/2024 11:20 AM

Doesn't sound like it is broken or that there is a fault so I don't know why you're focused on the pump prime rather than identifying the root cause of the problem/issue.

**Posted by Cab4word67** 7/08/2024 6:46 PM

Patrick the root cause is the pump prime curcit comming from the ECU as Holley stated. It is not always turning on. Problem is It will take 12 weeks for them to fix and I want to drive my car so this is a easy fix grounding the relay and adding a 4-6lb oil pressure sending unit and relay for the safety . Since I grounded the relay the car starts every time now. As tested sometimes the curcit would not turn on when the key was turned on but the handheld would.

Last edited by Cab4word67 (7/08/2024 6:53 PM)

**Posted by BobE** 7/09/2024 6:29 AM

Cab4word67 wrote:
Patrick the root cause is the pump prime curcit comming from the ECU as Holley stated. It is not always turning on. Problem is It will take 12 weeks for them to fix and I want to drive my car so this is a easy fix grounding the relay and adding a 4-6lb oil pressure sending unit and relay for the safety . Since I grounded the relay the car starts every time now. As tested sometimes the curcit would not turn on when the key was turned on but the handheld would.

I suggest you verify the EFI fuel pressure requirements, I believe the Sniper system needs about 60psi to function.

**Posted by Cab4word67** 7/09/2024 10:10 AM

Yes did that, new pump 60 PSI when on. Pressure gauge installed to verifie pump funtion