Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  
MIspecial

onan no spark

Recommended Posts

MIspecial
I got the motor back in, added a electric fuel pump and changed the points. I did make a mistake, while trying to prime the pump and fuel line a bumped the lead from the coil to the points box. I smoked! I was going to change them any way. I change the point and tried to start the tractor but no go. I pulled a plug held it to the block and no spark. I installed the plug and check for power on the other side of the coil while cranking and none. Could I have fried the coil or condensor? What else should I check? Motor is a 19.5 onan cckb on a power max.

Share this post


Link to post
Share on other sites
StanD
Are you sure you still have 12 volts to the coil, in both the on & start position? Check ohm readings between Pos & Neg on coil. It should read 3.87-4.73 ohms. Check between spark blug leads with wires removed. Should be between 12,600-15,400 ohms. All readings must be made with all wires removed. This is out of the Onan manual. StanD

Share this post


Link to post
Share on other sites
D-17_Dave
First off, as Stan said, check and make sure you have 12 volts coming into the coil on the + side of the coil. If this is so then remove the points lead from the - side of the coil. Check the coil by turning the switch on and with a piece of wire or a screw driver ground the - post on and off and see if the coil produces spark. This will separate the points/condenser/ wire lead from the coil to help diagnose between the two sections of the firing circuit. If you have spark then trace out the bad wire, connection, or points/condenser problem. If you still have no spark then you have trashed the coil. Replace whatever bad components you find.

Share this post


Link to post
Share on other sites
Al
Hi, You should not be able to damage the condenser with 12 volts. Check you have 12 volts to the coil. Then connect a small test light or a voltmeter to the negative side of the coil. If you have about the same voltage on the negative side of the coil. If so the points are either, open, not making contact due to oil etc. If you have 0 volts or no light, either the points are closed, or the lead to them is pinched and grounded, or the condenser is shorted. Next turn the engine over the voltage should come and go. You can check the same thing by pulling the points open. When I trouble shoot a 12v ignition system, I just use a test light and put it on the negative terminal, then crank the engine. If the light flashes when the points open and close you already know you have the 12 volts to the coil and the points are working and you haven't wasted time making another unneeded test. Next I jump a condenser from the minus to ground, if I get spark, I just found the problem. Al Eden

Share this post


Link to post
Share on other sites
bobjohn
In electical work, I have found that if I let the smoke out, the componet will not work any longer. So, apparently, all electonic parts have smoke inside that does all the work... bob

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this  

×