Happy New year

I replaced my manual choke with an electic one on my 79 351m the day before yesterday. It worked fine. Today iI can't get a spark. Lots of juice in the battery, I tested all the wiring to and from the battery, solenoid and coil, appears fine. I changed the coil (one that I believe was fine from an old parts truck I had about 6 years ago, worked fine back then, not leaking now appears OK). Visually checked the distributor cap and rotor, dry and sound.

I have some testing equipment but am not really knowledgable about the duraspark system, should I be able to get power with the ignition on from the electic modulator(?) inside the distributor?

I noted on a post earlier in the week an opinion that the electricall systems weaken after time and would concider replacing with new (but not right now). Any further checks that any of you gents would suggest?

Thanks in advance

Greg
79 f100 351m c6 long box
76 Merc Marquis 400m

 

>I have some testing equipment but am not really knowledgable
>about the duraspark system, should I be able to get power
>with the ignition on from the electic modulator(?) inside
>the distributor?

No, the pickup is a sensor only.


>I noted on a post earlier in the week an opinion that the
>electricall systems weaken after time and would concider
>replacing with new (but not right now).

Heat gets to the module after a while. The aftermarket modules not made by Motorcraft seem to be of an inferior design or manufacture and are more sensitive to heat. Even Ford says to mount the module 1/4" above the mounting surface to allow cooling air to reach under the module.

>Any further checks
>that any of you gents would suggest?

I would suggest looking for a bad connection or a broken wire that you may have disturbed. There are two power wires leading to the Duraspark module, Red and White. The white wire should be hot when in start mode. The red wire should be hot when in run mode. The system is grounded at the distributor module.

I would suggest taking the "brain box", as some call the Duraspark module, and the distributor pickup to an auto parts store and have them tested. They have little computerized testers that test the modules.


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The + side of the coil schould be hot with the key in the run and start position. The red wire to the module schould be hot in run position.The white wire to the module schould be hot with the key in the start position.Using a ohm meter disconect the plug from the distributor and check between the orange and purple wires schould
be around 80 ohms.If a very high reading pickup coil is bad.And probably 1st try annother module.


Larry