1. Registration trouble? Please use the "Contact Us" link at the bottom right corner of the page and your issue will be resolved.
    Dismiss Notice

Coil Problems With Key Ignition On?

Discussion in 'Intermediate CJ-5/6/7/8' started by My_75_CJ5, May 6, 2021.

  1. My_75_CJ5

    My_75_CJ5 New Member

    I just bought a non running 75 CJ5. It turns over good but won't fire. I'm sure the fuel system and carb needs to be gone I've but it won't fire with fuel directly in the carb so I figured it would go down the no spark route.

    I have no spark with a spark tester. I pulled the coil and outside of the jeep and hooked up with the key in the off position, the coil primary and secondary resistance seems good.

    Once I turn the key into the on position, I get no reading from the coil.
     
  2. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    You should actually be checking for voltage, not resistance. With the coil back where it belongs & hooked up and the ignition on you should see battery voltage at the coil + terminal, at the coil - terminal it should jump up & down averaging around 6 volts with the engine turning over.
     
  3. My_75_CJ5

    My_75_CJ5 New Member

    Thanks. So I'm at just under 6V with the key on and it drops to around 3V when cranking.
     
  4. Howard Eisenhauer

    Howard Eisenhauer Administrator Staff Member

    Take a spark plug & connect it to the ignition wire that runs from coil to the distributor, run a wire from the plug's metal base to a good ground. Crank the engine over & see if you get a good strong blue coloured spark.
     
  5. My_75_CJ5

    My_75_CJ5 New Member

    Am I able to accomplish the same thing with a spark tester? If so, I didn't see a spark. But I will try again with a better ground and a plug.
     
  6. PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    No point to pulling a lot of parts until you've verified the basic tune up stuff.

    Clean points, adjusted to spec, for instance?
     
  7. My_75_CJ5

    My_75_CJ5 New Member

    I couldn't figure out how to get the cog(?) off after removing the cap, rotor and dust cap. I now feel comfortable doing it and will check out the points. Is there any way to tell if the condenser is good or bad without just replacing it?
     
  8. timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    IMO the best test for a coil is to borrow a working one from another car and try it.
     
  9. we did that with a lot of things from our '70 suburban, so we could narrow it down to certain things.
     
  10. My_75_CJ5

    My_75_CJ5 New Member

    I think I'll just have to buy one, cheap enough and I found the negative terminal is slightly stripped anyway. But I'll keep that in mind for the future, so easy to swap in and out.
     
  11. a lot of people also don't have more than just their jeep with an external coil