Wiring My PMGR Starter

[RPM 1,247]

Disclaimer: I'm no auto electrician. I'd rather stack BBs than trouble shoot electrical issue on a car.

Several years ago I installed a late model (80's) style PMGR starter cuz I falsely thought I had a bad starter. When the motor got up to temperature the starter would barely turn over. I fingered it was the stock rebuilt starter getting heat soaked. Turned out to be a bad pristine looking battery cable from the fender solenoid to the starter. Starter problem fixed. Or at least I thought. 

This image is how my PMGR starter is wired, and what @Mach1 Driver asked to show. My battery is mounted in the trunk, with the 12 inch ground cable secured to a stud I welded to the chassis. The 12v positive battery runs up the right side interior to the stock location fender mounted solenoid. I have no fuses or diodes in the battery or starter wires.

I've been plagued with starter gear teeth being destroyed, and sometimes the starter mounted solenoid goes bad. One time both went bad. 

Just for info, another (bad idea) non-stock part I swapped is a Tuff Stuff 1  wire alternator. 

If this isn't enough problems to discuss, I can add some more electrical issues in having. Too much harassment on my lack of skills will result in being flagged as a spammer :)

Edit:

I just remembered shortly after installing my first Performance Automotive PMGR starter, the starter gear stayed engaged to the starter ring gear. It made a hell of a racket that can't be missed. PA replaced the starter, and I've not had one do it again.

 

[Mach1 Driver 597]

Wow, I'm in awe. You've replaced 10 starters in 4 years- this has got to be driving you nuts.

The drawing is the way Ford connected the early PMGRs and is nothing extravagant. Do you have a sense that this is some bizarre mechanical problem or something else? 

The battery is in the trunk and the starter solenoid is up front in the usual place. The fact that the battery is in the trunk makes me wonder if that isn't a contributing factor. What gauge is the red cable? The flip side is that the steel chassis as a negative conductor is nowhere near as conductive as a copper cable, and the battery is 15' further away through various weldments.

I know that most people don't like dealing with electrical issues. Do you think you could manage a voltage drop test? It might help explain something. We can take this discussion off line if you prefer.

[RPM 1,247]

Ya, at least ten starters, probably more. Driving me nuts? No, it's a short putt. I've come to expect it, and named my 69 Rosanne. As in Rosanne Roseannadanna, it's always something. I am getting mighty tired of working on the same problems.

At some recent point I've begun to believe it's something other than the starter. My first couple of starters were Ford. But somehow got hooked into the lifetime warranty crap at O'Reilly's. I think I got sucked into them when I bought one while on a road trip.

The battery in the trunk has also crossed my small mind. The voltage on the battery post and and the solenoid are always the same when checked.

The red wire is #2 USA made copper. I do have a #2 ground copper wire mounted at the chassis ground next to the battery that travels under the car and mounts to the transmission. And three other engine to chassis grounds.

I will absolutely accept your help and will do, or attempt a voltage drop test. There are around five guys who've been in the loop of Roseanne's problems, and are flummoxed at the cause. Not that they  compare at all to your knowledge.

I think you should know of this electrical issue also. When I added my factory (with Sanden type compressor) AC a couple of years ago, I noticed I was only getting around 10v at the compressor. Among other things I checked the voltage drop from the battery thru the solenoid, fuse box, ignition switch and AC switch.  It dropped from 13.9 at the battery to 12.25v at the fuse box, and 10.3v at the AC compressor. 

As small a volume of traffic this site has, we'll keep it here. The more eyes the better.

Thanks brother.

 

[Mach1 Driver 597]

I can't take credit for this one, it's from Woodchuck on VMF. Since it has a picture you will need to go to my Google Drive folder and open the Word file: Starter Solenoid.doc. Woodchuck is usually right, and I've only had to butt heads with him occasionally. With this you can perform a voltage drop test of the entire starting system.

https://drive.google.com/drive/folders/10FqYlsGT1XXr8B5TCF9WAASkU4vdPtuJ?usp=sharing
 

[jmlay 91]

[RPM 1,247]

Cool, thanks guys. I'll see if I can get to that this week.

[det0326 192]

I can see voltage drops causing high current killing starter solenoids but in all my time (and I am old) I have never seen low voltage break starter/ring gear teeth or starter snouts.  Some how I believe this is timing related. While I don't know you personally Bob, I do know from reading your post that your timing is set with a timing light and is spot on. Not sure how you are controling timing but could the advance in your distributor be sticking or if using a aftermarket box could it be at fault?

[RPM 1,247]

My ignition is all Henry Ford circa 1969. Points, condenser, Motorcraft distributor, timing set at 18°, no vacuum advance.

Motor is a 393W with a 3.85" stroke, AFR heads, with 10.2cr.

A couple of guys have mentioned that the stroke and compression ratio might be a stain on the starting system. But the M code 351w came with 10.7cr. 

I've got an issue with my motor where it fouls two to four plugs during city driving, but not on long trips. As the plugs start to foul it takes longer crank before it starts. The starter failures seem to occur during these longer cranking times. With fresh plugs it starts up right away first moment I turn the key.

I've had the intake manifold off three times for various reasons and the gaskets have not shown signs of leaks. The valves have been lapped, and Viton seals installed. The stock AFR valve guides felt good when checked.

I have a coil cut off switch, and have on occasion not turned it on until it cranked for a second or two. It seems to start easier this way. 

I've got a freshly rebuilt 5.0 roller motor in my 56 F100 that just might get yanked out and put in the 69  :) They said build a Mustang, it'll be fun!

Oy...

 

[det0326 192]

I had the OEM starter on my 351w in the beginning and had the same problem as you mentioned about heat soak because of headers. I changed to the PMGR starter and that seemed to fix the issue, my engine had a CR of 10:1 with AFR heads. Another thought crossed my mind. Do you have a 157 tooth flex/flywheel or 164 set up. While the 157 tooth should not cause your issue it would add extra stress on the starter.

[RPM 1,247]

I have a 1986 E6ZR-AA 157 tooth 50 oz flywheel, that was balanced to my 28 oz flexplate weight because the first machine shop added weight to my flexplate when he balanced the motor.

[det0326 192]

Has this flywheel been on the engine the entire time you have had starter issues?

[RPM 1,247]

No. I also had starter issues with the FMX and flexplate before I put in the toploader. And I like the way you think.

[RPM 1,247]

Welp Terry, be careful what you wish for. I hope I don't fry your brain with my voltage drop numbers.

1-  2.3v drop

2-  went from 12.6 to zero

3-  12v drop

4-  1.5 drop

5-  .25 drop

6-  .25 drop

Before doing the test I checked the battery voltage. While looked at the digital gauge, the hundredths number was dropping by a hundredth each second. And cuz I'm not an erectrician, I don't know if this is normal. 

Bob

[det0326 192]

Bob if test 1. was a 2.3v drop test 4. should have been equal or a little more of a drop than 1.  You may want to check those two again.

By the way a 2.3v drop is not good. Maybe time to run a copper cable  from batt grn to engine block

[Mach1 Driver 597]

1. Lets make sure we are on the same page. Before doing the test, switch the meter to ohms, connect the leads together and move them around to be sure there are no internal breaks in the probe leads. Be sure to switch it back to DC volts before doing the tests. You installed a new starter, and it is cranking the engine over when you do these tests? How are you making the connections at Bat+ and the front solenoid terminal? Since your battery is in the trunk and the solenoid is up front, you need to connect a wire solidly to B+ and run it to the front, make a good meter connection, and then the other probe to a good connection on the front solenoid terminal. I would stick a short piece of stranded copper wire under the solenoid nut and tighten it up. Then make a good meter connection to that. Make sure the test probes are tight in the meter.

2. It looks like the solenoid is really good.

3. If it was 12v across this cable when cranking, then the starter wouldn't turn.

As Dave mentioned, the numbers don't make sense. 1+2+3= 14.3v, which is more than the 12.6v of the battery, and that doesn't leave anything for the starter- in fact its an impossible number- its negative. This would say that the cable from the back to the front is essentially open. The total of 1+2+3 should be no more than .3v, which leaves 12.3v for the starter (.3+12.3=12.6). These numbers are in a perfect world, and we don't live there, but so far these are really bad. Try again my friend.

[RPM 1,247]

I rechecked them all and not much changed. 

I do have a #2 copper ground from the trunk battery ground stud to the tranny tail housing.

Even though I ain't much of an electric guy, one trick I was taught and use regularly is the ohm check. Both leads are inserted fully. 

I ran a jumper cable from the battery to the front where I used the voltage meter. And turned the motor over while checking the voltage drop.

Here are the numbers from the second test. 

1-  2.0v drop

2-  12.1v drop

3-  12.6v drop

4-  1.3v drop

5-  .22v drop

6-  .16v drop

Think I'll check all terminals and connections, and make new wires from the solenoid to the battery.

[Mach1 Driver 597]

A 1990s Ford PMGR will draw:

Starter Current at 1500rpm: 308amps (390amps would be a fail)
Starter Current at 750rpm: 523amps (600amps would be a fail).

Looking at a chart for starter cable, that only goes up to 300 amps, and for a length from 4 to 28 feet, it says use 1/0 gauge cable. Another chart says for 250 amps (the max on the chart) use 1/0 gauge for 6-12' and 3/0 gauge for 14-20'  

2 ga is good for 4' at 225 amps, or 13' at 150 amps.

Your last test in #2, and #3 indicate an open circuit for the solenoid and the long cable, so the motor shouldn't be running. You either have bad connections or need to use another meter. Do you happen to have access to a good analog meter like an old Simpson 260 or a Triplett? This type of test causes lots of electrical noise that can frazzle an electronic meter, unless its a really good one like Fluke.

 

[Midlife 838]

Quote

I do have a #2 copper ground from the trunk battery ground stud to the tranny tail housing.

No!  The tranny tail housing may not give a good ground to the chassis: please re-locate to the unibody.  This may be the source of your problem.

[RPM 1,247]

5 hours ago, Midlife said:

No!  The tranny tail housing may not give a good ground to the chassis: please re-locate to the unibody.  This may be the source of your problem.

Just for clarity, in addition to that ground wire at the transmission tail housing which connects to a lug next to the battery in the trunk, the battery connects to the chassis at that lug in the trunk. I also have three engine block grounds to the chassis in the engine bay.

[RPM 1,247]

Terry, the best I've got for analog testing is an AWS SPR-300 plus, and an old Sears Penske automotive analyzer model #161.21042.

Back ten years ago when building the 69 I just bought the trunk battery cable kit online which was sold for this purpose. I figured it was up to the chore.

[Mach1 Driver 597]

Well they're what ya got so why not give 'em a whirl. Does the last one do DC also? It looks like the Sears unit can measure to 0.2v.

Reserve judgement on the wire gauge until you get a good measurement, but from everything I read, it's undersize. 

[RPM 1,247]

Okay, some new numbers. I'm pretty sure I said I'm not an electrician. Tonight I was on the phone with a fellow Mustanger buddy when I was starting the test. When I questioned him about the voltage drop on the #1 procedure on Woodchuck's chart, he told me the number I was looking for was the cranking volts, not the drop difference from before cranking and while cranking which is what I had been listing as the value. 

I used a new digital volt meter for the latest test.

1-  .95

2-  .00

3-  .19

4-  11.80

5-  .23

6-  .20 

Terry, I was told that Woodchuck's chart is for a chivy with one solenoid. What measured values do you think should be expected with my stock fender mounted solenoid and a solenoid on the starter?

[Mach1 Driver 597]

OK, I'm not judging here, I just want to understand- what was the number you were calling "drop" and how did you get it?

I took your picture from post #1 of the wire diagram and marked it up . Go to my google drive and get this file:

"Bob's voltage drop test.docx"

https://drive.google.com/drive/folders/10FqYlsGT1XXr8B5TCF9WAASkU4vdPtuJ?usp=sharing
 

 

[Nos681 2]

I prefer to use the battery (-) for all measurements.

 I understand the convenience of test points.

I like the marked up drawing Mach1driver.

 

WC’s picture can make it confusing when wiring does not match the “as built” wiring…even for an electrician.

[RPM 1,247]

Judge away Terry, most of my friends do :)

An example would be the #4 of my first test where before cranking the volts at the battery connection (forward big lug) on solenoid measured 12.6v and 11.1v when cranking, I came up with a 1.5v drop, instead of giving an 11.1 value.

The cable from the + battery post in the trunk to the solenoid is pretty close to 15 feet.

In your Word post questions, to which starter terminals is #3 measuring, B to C? And which terminals is #4 referring to?