1973 - 1979 F-100 & Larger F-Series TrucksDiscuss the Dentsides Ford Truck
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Had the truck running fine until today, cranks just fine but won't fire at all. I've got 12V at the coil and at the end of the plug wire running from the coil to the distributor cap. When i pull a plug out and try to see a spark out of it I get nothing. I also don't think its the ignition because I'm alone and when i try and start it to look at the plug I have to turn it to run and jump it at the solenoid. I also don't have a test light. What do you think I should check using the multi-meter I have?
I've got 12V at the coil and at the end of the plug wire running from the coil to the distributor cap.
Clarify this part a little more... you have voltage to the coil, that part is clear, but you state you have voltage coming out of the coil at the post as well?
How did you check that?
Now, to substitute the DMM for the test light, turn the DMM to DC volts, hook your positive to the TACH side of the coil and the negative to ground. Now try and start the engine, the DMM should pulse between 0 and 12 telling you whether the module and pick-up are good or bad.
Also in the meantime you can test for OHMS on the distributor leads, the wires should be orange and purple and the scale is 500-800 ohms.
It's a little hard to do by yourself without a test light, but if you have alligator clips for your multimeter, you can do it. Set your meter to read DC volts. With the coil connected, connect the multimeter between the TACH TEST terminal of the coil horseshoe connector and engine ground (clean unpainted metal on the block). Use the key to crank the motor over, and the meter should flash between 12 volts and zero.
This is equivalent to connecting a test light in place of the multimeter and watching for it to blink. If your multimeter doesn't have clips, you're going to have to have a friend crank the engine over from the cab while you hold the meter in place. To do this test, you have to use the key to crank the engine over. You can't jump it at the solenoid because you need the ignition switch to power the ignition module for this test.
EDIT: looks like Josh and I posted at the same time.
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