Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Sign in to follow this  
babablacksheep

720 cckb ingition problem

Recommended Posts

babablacksheep
Hi. I have a 720 with the Onan CCKB and a wierd ignitinon problem. The tractor was hard to start after I used it the last time and turned it off outside the barn. Acted like the carb was flooding, blowing black smoke out the exhaust, etc. I managed to get it runing long enough to get it under cover and shut it off again. When I went to start it later, it gave one sputter and then refused to do anything. I pulled the carb, blew it out, adjusted the float and reinstalled. Same result. After numerous kind and considered comments about the ancestry of Onan engines, I put a spark tester on it only to discover that I was getting one flash when I hit the starter and that was it. I had to let it sit for a half hour before I could get another single spark. I'm leaning toward a bad condenser, but I've never had this particular problem before and wonder if anyone else has. I would appreciate any input before I take the muffler off so I can get to the point box without being a double jointed contortionist. Thanks guys

Share this post


Link to post
Share on other sites
JP
Onan's have a tendency to go through points (sometimes). It most, they're finicky as 'heck' on the timing. There's a few things to do; Check for oil in the box. You may need a new plunger, bushing, seal or all of them. Clean & Set your points to .020, THEN check with a timing lite. Get that out of the way & let us know what it does..... JP

Share this post


Link to post
Share on other sites
D-17_Dave
JP's got you on the right track. The CCK's have a history of points problems. I have witness'ed this on more than one occasion myself. The screws that hold the points inside the box will wear over time and slowly let the points close up and burn. When this happens the jumpy timeing will mimick several diff. odd running conditions that include carb problems and/or little power and so forth. The odd thing is most of the time I find that you still have resonable spark, but not steady enough to run properly. The coil may also be showing signs of a fault by giveing the points too much voltage burning the points prematurly. If you seem to go through severalsets of points in secesion I'd look closely at replaceing it. Most of the time the cil just goes completely out. If you want to cheat a little and try to elliminate the coil or isolate the problem as inside the points box then remove the wire from the coil on the - side and with a piece of wire short this term. to ground repeatedly and each time it should throw a great spark with the switch on.

Share this post


Link to post
Share on other sites
babablacksheep
Ok fellas. I finally got time to work on it today. The coil sparks just fine when you touch a wire from the negative to ground. The points, though a bit worn, seem to be are gapped OK and firing regularly. No skips. With a circuit tester on the coil wire at the negative termial and the ignition on and cranking it appears to have plenty of fire and the points doing fine. Output from the coil to the plugs is zilch, nothing, dead as a doornail. I took a coil from a parts engine I have and got the same result. Are we looking at the condenser not putting out enough to excite the coil to fire?

Share this post


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

×