Ford 640, no spark

pobox1589

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Long Time Reader, First Time Poster

Got a 1952 Ford 640 that will crank, but getting no spark at the plugs. Was converted to 12V, Negative Ground before I bought it (had it for 3 years), but recently installed a Pertronix Electronic Ignition as I was changing points every year before that. Recently had to replace the alternator and fan belt, but I don't think that should have affected it.

I got about 5 hours of use out of it this year before it sputtered and quit on me and hasn't started since. Was pretty confident about the fuel/carburetor system, and it's getting fuel to the carb, but I worked through that last year and am not too worried about that.

Battery has good charge, engine turns over great, but when i test the spark by pulling the plug wires off and hold it to the engine block, while running the starter, I get nothing. I've run the multimeter from every cord and connection that makes sense; most notably, between the ground and hot side of the coil and it's got 12 volts. Thought it was the coil at that point (have a high-performance coil on there now as it was recommended for the electronic ignition), but I'm still only getting 12V out of the top of the coil when I run the starter, so, of course, no blue spark when I pull the spark plugs off to test them.

Thus far, I've replaced (not all at once), the coil, distributor cap, and rotor button, hoping for a bad connection somewhere in there, but no dice. Additionally, I took the electronic ignition off and cleaned off the plate it mounts on in the distributor and cleaned that too. If it's a bad connection with the ground, I'm not sure where it's at.

It sounds like the electronic ignition isn't breaking the circuit, so the coil isn't sending the high voltage back through to the distributor cap and on to the plugs.

Any help that anyone can offer is appreciated. I'm afraid I"m going to have to take it to the shop if I can't get it fixed, but i pay for the education there. Thanks again.
 
Instead of checking for spark coming out of cap, check for spark going into cap. Pull center wire from distributor and place it near block. Check
for spark when turning over engine that way. Also, distributor is turning right? Hope this helps. You could install points and cond to see if maybe
your electronic ign went bad good luck
 
I would first call Pertronics for specific or more in-depth troubleshooting steps. But here are some general things to try that will not harm:

The module is just a switch. You can check for proper function by attaching a test light to the negative post of your coil and then ground the test light probe. If module is working, the light should flash on and off while cranking.

Also, ensure the pickup collar is firmly attached and rotates as engine turns over.

Improper or intermittent ground to the module cause many failures.
 
Roger, I pulled the center wire off the dist cap, held it to the block, still no spark. Distributor seems to be turning correctly (clockwise). Thanks!
 

OK, first off figure out what tractor you've got. The 00 series were built from '55 to '57. A '52 would be an 8N. Then do te steps for testing the electronic ignition as you've planned.
 
(quoted from post at 11:20:02 05/05/18)
OK, first off figure out what tractor you've got. The 00 series were built from '55 to '57. A '52 would be an 8N. Then do te steps for testing the electronic ignition as you've planned.
W rotation of distributor means that it is NOT an 8N.
Put points & condenser back, start it up and go to plowing.
 
(quoted from post at 10:36:09 05/05/18)
1955 Ford 640 (SERNO 91418, says 640 just above it). Sorry about the typo.

I have 1955 640 that's runs beautifully on the points and condenser. Before and after pics

15990.jpg
15991.jpg
 
First..Touch your test light or voltmeter to the coil with the ign switch on to see if you're getting voltage to the coil. No voltage to the coil you're never going to get a spark.
 
Just to close this out, I took it to the garage and they confirmed what I had thought, the electronic ignition module had gone bad. Reinstalled points. The ignition module was only 6 months old, so I'm going
to contact the vendor and try to get my money back. Thanks for the help, everyone, see you down the line.
 

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