Starting problem

[skybanker]

Does anyone have any idea why my Comanche 250 will not fire when cranking with the key in the "Start" position but will fire and start when the key is released to the "Both" position? It has also began kicking backward sometimes when you let up on the key. In fact, it kicked back and broke the starter case, which has now been replaced with a B & C starter.

[skipsouthernsky]

Dear Boyd,

Does your starting system use Mags with impulse couplings or with "shower of sparks"? Assuming it is shower of sparks, do you hear a buzzing when the mag switch is in the start position? If not, then the shower of sparks box is probably worn. You can replace it or take it apart and sometimes clean the points inside. There are several ways to disable the starter, but with the starter disabled, you should be able to hear the buzzing very clearly. With a good shower of sparks box, you can probably hear the buzzing even with the starter engaged.

If you have impulse couplings, then the mag will have to come off and be opened up to see what is wrong. Probably either a broken spring or broken pawl/stop pin.

One other thing, are you sure your problem is no spark? The same symptoms would appear if the engine is not getting any fuel. I guess if the engine kicks back, it is probably getting fuel, scratch that thought. You probably have shower of sparks and the box isn't putting out. That's why it kicks back. When you let off the start position, to the both position, the engine is still rotating and both mags are hot and firing in the normal advanced timing. That would cause the spark and firing of the fuel before top dead center and a resulting kick back.

Sincerely,
Skip Dykema

[skybanker]

Thanks Skip. I will have my mechanic check it out.

[JIMICS2452]

Check the mag timing and point gaps. That caused the problem on my 250 years ago. I am kind o picky about that now.
Jim Hiatt

[Chuck 88P]

Also, check the connector lead on the retard position of the left mag. Not the Plead to ground the mag, the other one, and it should be labeled retard. If you don't have shower of sparks you have an impulse mag and disregard this note. If contact is not bright silver, scrape the oxidation off lightly with a knife (it is just solder). I screwed around for a long time with mine until Bob Weber via a phone call put me on to the 5 min fix. The ignition switch will not let either mag fire except the shower of sparks circuitry in the retarded mode on the start position. This is why it won't fire until you let off of the start position on the switch. It is also why it kicked back, because you were firing at 25 dgrees advanced timing in regular run mode. If this is not it, you will need to go through the service manual trouble shooting procedure to verify that the shower of sparks works.

Chuck

[Bill Hix]

Had the same problem with mine. Found the distributer gear was warn enough that when the starter was engaged it would torque the gears apart resulting in the mag going out of time. When no load was placed on the mag it would work fine.