New coil no spark

[beg]

I have a Lawn boy model 4600 with the f motor which has a ground terminal on one of the screws for the coil and a terminal on the coil itself. I installed an aftermarket coil for an f motor but have no spark Is this new style coil being shorted out somehow or did I get a bad coil out of the box? I bought 3 of this style coil and installed the other 2 with no problems but the 4600 must have a different wiring system.

 

[jp1961]

Did you try switching the wires from the plunger switch?

Jeff

 

[beg]

the two wires are in a harness with a plug but I can switch the terminals around at the coil end and see what happens It may have been hooked up wrong from the PO

 

[motoman]

I do not know your machine. If it only uses a coil, voltage higher than 1/2 volt ( like battery voltage) will destroy the stuff inside. This problem apparently kills many Briggs Magnetron coils. If you search this forum you will see evidence of newly purchased coils dead on arrival. IMO especially the really cheap ones .

 

[Phototone]

Early "F" engine coils were grounded to run. Later "F" engine coils were grounded to stop. The earlier coils are no longer being made. Your replacement coil is most probably the grounded to stop variety and it can still be used on the earlier "F" engine mowers, just turn the on-off switch to "OFF" to run, and "ON" to stop. I know it is confusing. But try the coil with the kill switch set to the off position. I bet you get a spark.

There is no battery. It is a self-contained magneto-type ignition module with no points, on an "F" engine. Excited by the magnets in the flywheel. Even it you have a model with electric start...the whole battery-charger-electric-start system is totally separate from the ignition coil/magneto. There is a separate coil, totally independent mounted near the flywheel that generates a charging current from the magnets in the flywheel. Not connected to the running of the engine at all, and the engine can run just fine with all the electric start stuff removed.

 

[beg]

I have one of the early converted f motor setups and yes off is on but this one a model 4600 has the bail flywheel brake system it cant be too hard to figure out its only 2 wires and its being shorted out somehow. I will get to it this weekend and see what the deal is and put a reply to this post to assist other forum members who may run into this issue.

 

[Phototone]

I have one of the early converted f motor setups and yes off is on but this one a model 4600 has the bail flywheel brake system it cant be too hard to figure out its only 2 wires and its being shorted out somehow. I will get to it this weekend and see what the deal is and put a reply to this post to assist other forum members who may run into this issue.

OK then, the coil should fire with the harness for the bail break switch disconnected. If it doesn't, then the coil is bad. Normally, I test a coil by clamping the flywheel brake off with a visegrip on the handlebar, remove the sparkplug, and keep plug wire connected to plug, ground plug against side of motor and spin flywheel by hand, fairly quickly. It should spark with every revolution of flywheel. You can test the brake/bail kill switch by using a multitester and read the continuity between the wire that connects to the coil, and ground. With brake bail disengaged (no braking on flywheel) there should be no continuity, with the brake engaged there should be a dead short. (This is with the wired disconnected from the coil).