Tecumseh HH100

IrvIA · Jan 13, 2013

Here's a story on what happens when your age and the old thinker shorts out. I'm back working on a 1968 John Deere 112 after leaving is set apart for about a year. The elecronic ignition must have quit before I bought it so they put points back in and a coil on it with plumbers strap on the back of the engine. I made a bracket for it and it fits nice. I redid all the wiring and fired it up. It ran poorly so I tested it and it
had weak spark. I'm thinking the coil is bad so I got a new one, put it on with the same results. I'd had enough for one day, so I go's to the house and complains to the missus about it. In the process a light comes on.....I never put a condenser on it.
Get's one the next day and it run's great!!
Now my question is... Have you EVER had ANYTHING that would run at all without a condenser?? Sorry for the long post, but I'd sure like to know!!
Irv

Anonymous-0 · Jan 13, 2013

Many years ago we had a military surplus Wisconsin single cyclinder on a water pump. We converted it from the military cap to a civilian Wisconsin cap and wire. It was extremely hard to start, wouldn't rev hardly at all. Because the engine had set, we figured the carb was the problem. Had it on and off several times, cleaned it out and reinstalled it, same crappy running. Finally a light bulb went on! Yup, the military cap had a condensor built in, the civilian one didn't. Added a condensor and it ran great!

IrvIA · Jan 13, 2013

Yep, I've had my carb bowl off three times too. The first time it NEEDED it.. full of rust flakes and the float was set incorrectly. Now the bowl leaks too, so back to the parts store for gaskets and a O-ring. I turned the gas tank off and on so many times now it leaking too. Sediment bowl gasket, I think. Hoo boy!
As for the condenser, how does it work without one? Just enough residual current in the coil?

MNGB · Jan 13, 2013

Last year that happened to me o a HH100 the coil that came with the engine had a capacitor mounted on the coil well I couldn't find the coil so I just grabbed another one an no spark figured it was a bad coil tried another same results finally the light came on and I found the other coil with cap istalled it had spark and the engine started up and ran good. No haven't seen one that would fire without a cap.
GB in MN

IrvIA · Jan 14, 2013

Is seems like my light is off more than it is on these days. <grin>
Irv

Anon · Jan 14, 2013

Did it once myself and yes it started hard but started-and it would only idle. As soon as you tried to give it throttle would quit.

joe csuti · Jan 14, 2013

With an electrical circuit that has an inductive load(coil)when the sw contacts or points open a back emf or spike voltage is generated up to 3X the supply voltage for a fraction of a second as the magnetic field in coil is collapsing

The function of the condenser is to absorb/quench this spike voltage to reduce voltage to as near 0V as possible before next close/open operation of points,this now gives max voltage buildup in coil primary & giving max hv to plug,without condenser or if condenser open/shorted voltage in primary of coil stays high & gives the same effect as points not opening,the condenser also prevents arching/burning of point contacts.

I've had the same experience as anon with several briggs eng with a bad/weak condenser,eng would be hard starting & only run rough at idle/slightly above & when you goosed throttle eng would die.

IrvIA · Jan 17, 2013

I've also had that when the condenser was bad, but mine wouldn't run at all, like you said, beause it was open/shorted. I was just confounded by the fact that it would run without one.
Irv

IrvIA · Jan 17, 2013

Thanks for the lesson on just how that all works. Kinda remember that from reading a Motors Manual forty years ago, but sorta lost the details.

Irv

Tecumseh HH100

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