low spark

[Joe Williams]

this might be a dumb question but what causes low spark?

 

[jbratton]

Assuming you have a battery ignition:
Bad connection
Bad coil
Bad condenser
Bad spark plug

 

[mgonitzke]

What model tractor?

 

[HKCooper44]

Incorrect point gap can cause "low spark", as can a faulty, but not completely shorted condenser.

 

[gary noblit]

Joe,questions aren't dumb ...sometimes the answers can be....keep asking..

 

[kharvey]

Low battery voltage when cranking can cause weak spark. Not enough voltage going into the coil.

 

[Joe Williams]

What model tractor?

 

[Joe Williams]

105

 

[dschwandt]

I might add crappy, corroded, improperly spliced wiring w/corroded terminals at the switch and throughout the length of the wire.
Electrons do not like cruddy corroded conductors and get hot due to increased resistance and have a tendency to self destruct plastic connectors etc.
If your wiring is stiff as apiece of #9 wire and hard as a rock it's time for a new harness.

 

[Joe Williams]

should there be voltage on the plus side of coil when you turn on switch?

 

[HKCooper44]

should there be voltage on the plus side of coil when you turn on switch?

With the ignition switch on, the "+" connection on the coil should be battery voltage. The "-" coil connection goes to the points.

 

[Joe Williams]

yea i'm not getting any voltage to the coil

 

[HKCooper44]

yea i'm not getting any voltage to the coil

Do you have the model 105 wiring diagram? You can get it off of Google.

 

[Joe Williams]

thanks i dont have one ill look it up

 

[HKCooper44]

thanks i dont have one ill look it up

Print it out. It will be easier to use out at the tractor.

 

[gary noblit]

Joe, a jumper wire with alligator clips on the ends...one on batt. pos. ..one to pos. on coil should give you the answer....if it works it's connections or switch..

 

[lpalma]

Incorrect point gap can cause "low spark", as can a faulty, but not completely shorted condenser.

Points plunger made need to be replaced also.

 

[HKCooper44]

Pull the spark plug and rotate the engine to top center on compression and set your points to .020" (going from memory here). Rotate the engine a few more times, and if the point gap holds, your pushrod is likely OK. Mine is the original in my 60 year old model 100, and is still working fine.

 

[lpalma]

You cannot see the piston from the spark plug hole. Use the mark on the flywheel to determine TDC.

 

[HKCooper44]

Use a thumb. It'll be close enough.