Hello all. I have a 75 F250 with a 300. I converted to a DS2 distributor 3 years ago. I tested my MSD box and it is good. I have good spark from the coil, but nothing to the plugs. The small module inside the distributor, under the rotor, does that go bad?

If so, where to get the best quality replacement? and how do I replace it?

Thank you for your help. k

 

D4PZ-12A112-A .. Stator aka Magnetic Pickup Coil (Motorcraft DU-1A) / Available from Ford & auto parts stores.

ALL 1974/79 Ford V8 vehicles with DuraSpark except 1979 LTD/Grand Marquis 351W with EEC (on board computer).

 

the magnetic pickup coil is what triggers your coil to spark, so if you have good spark at the coil, you have a problem between there and the plugs (coil wire, dist cap, rotor, plug wires, plugs)

 

I agree with dlburch, if you have spark at the coil the problem is in the secondary side of the ignition. My first suspicion would be the rotor. If you're testing the spark at the coil using the coil wire, that would mean the coil wire is good also. Doubtful all the plug wires would be bad so that narrows it down to the rotor or distributor cap.
If you didn't use the coil wire for the test that would also add the coil wire to the suspect list.

 

I tested spark at the plugs and had nothing. I tested coming out of coil and had nothing. I tested the msd box by disconnecting the magnectic pickup wires to the dizzy, from the msd box, turning on the key, and jumping the wires, as instructed by msd. Doing that I had good spark from coil to dizzy, but nothing to the plugs.

That tells me--and correct me if I'm wrong--that the magnetic module is not sending a signal to the box. I also noted that the cap and rotor are in a sad state. I will replace tomorrow and see if that is the blockage in the dizzy preventing current from reaching the plugs.

Thanks to Number Dummy for the part number. You offer a great service to the forum. Not to detract from N.D.'s efforts, but have read the Chrysler mag. pickup modules simply don't go bad, and am considering replacing with one. This dizzy was completely rebuilt 3 years ago, and if a module only lasts that long I'd rather go a diff. route.

kevin

 

if you are saying you were manually making and breaking the circuit through the low voltage side of the coil, then you wouldn't get any spark at a plug, UNLESS the rotor was aligned with one of the plug towers...then only that one plug would fire. If you don't have spark at the coil when cranking, then yes, the pickup COULD be to blame.

 

Oh boy! Thanks.

Overall, I was looking for something like this:

Troubleshooting a Duraspark distributor
As mentioned before on a duraspark system, the actual disruption of power through the coil is done by the ignition module, but in order for it to know when to switch on and off it needs input from the distributor. This signal is provided by magnetic pick up inside the distributor. A duraspark distributor has three wires in the connector: orange, purple, and black. The orange and purple wires are hooked up to the magnetic pick up and the black is hooked up to the hold down screw inside the distributor and serves the purpose of grounding the distributor to the ignition module.

The first step in testing the distributor is to touch one lead of your meter to the terminal on the end of black wire and the other to the distributor body. This should show a reading of 0 on the meter meaning a good connection between the black wire and the distributor. The next thing to check is the magnetic pickup. This is done by touching one lead of the meter to the terminal on the end of the orange wire and other lead from the meter to the terminal on the end of purple wire.

The reading on the meter should be between 500 to 1,200 ohms. If your reading is in that range switch the meter over to AC volts and spin the distributor shaft. This can either be done by hand if the motor is out f the car or by cranking the motor,with the key in the off position, if the distributor is still installed. When the distributor spins the reading on the meter should be around one volt AC. If you do not have around one volt AC than the magnetic pickup needs to be replaced. Some auto parts stores sell just the magnetic pickup, but many only sell full distributors.

Thanks to all.

 

When I look up the part Motorcraft DU-1A, I see there are two sections to the unit. There is the actual sensor that is screwed/attached inside the distributor, and another part connected to the former with wires. It looks as though it mounts outside the distributor?

I have the sensor inside, but not the unit outside! My sensor is wired directly to the msd box. I had my dist. rebuilt from J/Y by a distributor 'shop'. Can someone please explain what the part is that mounts outside the distributor. Thank you.

 

nothing mounts outside the distributor. the rubber grommet has a metal ear that has a screw inside the distributor...and the wires are all that are external to the distrib.

 

Thanks for clarifying that. I was looking at a bad photo and couldn't tell that the part I thought attached to the outside of the dizzy was actually the wire connection.

I am off to purchase an ohm meter and test my pick up, and will change if I need to. I'm happy to learn that the task can be completed without having to pull the dizzy.

I thought my stator/pick up would last much longer than 3 years. But for all I know the shop who rebuilt/recurved it may have used the original one, and that would make it 36 years old.

They seem to be getting difficult to locate, so, for the future and for trips, I found a NOS one on ebay for $20, motorcraft. It's always good to have a back up.

A couple of parts that do wear out quickly since going to the high energy ignition, is the cap and rotor. Max I get about 3-4 months out of them.

 

12A112 in pic =

 

Well, I tested the pick up. I have zero ground, no screw to plate, no wire. In the msd drawing they show to not use the black ground wire anyway. I will run the new to its own ground. The book said it should have 1 v when spinning. I got 3+. Ohms came in at 230 and that is in the range. Well, I'm perplexed.

I have tested the msd and it is good. I've tested the coil and it is good. I've tested the mag. p/u and it reads high, but I don't know if that means it is okay or not. I have now new cap and rotor. By eliminating the parts I know to be good only the p/u remains suspect. Time to install new.

I did find the plate that holds the p/u is all rusted. The retaining clip was off and the p/u wobbles. That must do wonders for my timing. I always assumed the timing fluctuated on the light b/c of the msd and induction type light. Now I'm wondering if it has been like this since the start. And I wonder why the garage based home shop who did the distributor won't answer his phone!

 

Normally I don't like to be surprised when doing mechanical work. All surprises in the past have cost me money. This was no exception. While prying out the magnetic pick up gear (stator?) I noticed I could pull it up 3". I didn't try but thought I could pull it right out.

I'm assuming that either the shaft snapped or I sheared the pin that holds the drive gear on, and possibly the gear is in the oil pan. I'll know more when I pull the dizzy.

Added later: I'm quite surprised that not one member with knowledge of distributors chimed in. I searched the web high and low and found zip. Numberdummy's diagram was the only source I could find.

 

A lot of us wait for fmc400 for all electrical questions because he is accurate and knowledgeable about trouble shooting these vehicles.

 

HEADS UP: I thought this might help some dent owners: The magnetic pick up assembly part # DU 1A (motocraft) is obsolete. Ford dealers sold it for $160. Now it is being made (guess where) overseas, and it costs $40. The original lasts about 40 years. When you pay about 1/4th the price, guess how long it will last? I would guess 3-4 years. But, the original Motorcraft ones can be found on ebay, NOS (new old stock). I got one for $20 in the original box.

It is easy to change, and can be done with the dizzy in the vehicle. Mark the position of the trigger gear before removal. Have one of those telescopic magnets handy for small parts. Tap the keeper pen down (used an old drill bit) and pry off the gear--after removing the dizzy housing (two screws, the cap, and the v.advance (two screws). If the module blocks the gear from coming out, just move the module with the v.advance action, or click the engine to spin the rotor/gear tooth out of the way.

With my new one I crossed the wires when soldering on the msd plug, and that caused the problems until I found the mix up.

Note: Yeps, I love the ease of the pointless ignition, but a set of points never failed and left me stranded. It may have made the engine run poorly, but I always got home with them.

Thanks to all for the help.