Weak Spark (1 Viewer)

[Aussie 25]

I have a FJ45 1977 that has a weak spark. Have put new condenser and points, set gap at .45mm, leads test good and cap looks ok and changed the coil. Hoping someone may have had this problem before.


Give me a diesel aneyday.

 

[edwjmcgrath]

How are you measuring the weak spark? From a sparkplug wire?

Try pulling off the HT wire from coil to middle of distributor and check the spark from that wire to frame while cranking. If that is a strong spark, that will tell you that either the rotor, distributor cap, or plug wires are the problem.
Do you have a ballast resistor? How are the connections on that? Those can easily be loose and cause weak spark. Try just bypassing that resistor (briefly for a test only) to see if that is the problem.
Then to see if the ignition switch is the problem, replace the positive feed to the coil with a direct battery connection (again, briefly for a test only).

 

[desertpat]

Engine Well Grounded?

Is your engine block well grounded to the frame?
Easy to check out.
cheers

 

[LOOMER]

how can you tell a weak spark from a strong spark?

 

[edwjmcgrath]

If you can get a half inch spark that is blue, constant, and makes a nice crack, that is a strong one. A quarter inch or less and reddish and intermittent is a weak one.

 

[Aussie 25]

Fixed It

Thanks for your help. I done all the sugested checks, no good, last one was hookup a seperate battrie and it ran well. Rehooked up orignal battrie and i noticed the amp gauge was showing a discharge with the engine running, Disconed the voltage regulaitor and fixed the problem.
The fix, fitted a new voltage regulaitor. I havent struck this before.
Thanks again for the help.