720 Won't Start

I had been using my 720 throughout the day to pull my garden trailer around with tools in it and it had been running well and consistent.  I pulled up to the garage to get a couple items and left it running at low idle.  It died on me before I returned, but sat there only a minute or two with the key on and electric fuel pump running.   Wouldn't start, so I figured it was flooded.  Let it sit for a couple three hours, and still would not start.  Took air cleaner cover off and gas ran out.  Pulled it into the shed and tried the next day.  Still won't start.  It has now been three days, and it does not want to start.  Has spark, and obviously gas.  Any ideas?  Just really flooded and need to let it sit for an extended period of time?  Thanks for any input.  Dave

Well, went and checked and there is gas in the crankcase.  I'll drain it and put new oil in.  Darn, just changed oil in it a couple of hours ago.  Hope that solves the problem.  Hope it didn't do any additional damage.  Thanks, Dave

I would also pull the plugs and spin it over to see if it spits out fuel. May have also fouled the plugs.

Well, it was raining today, so an inside job.  Changed the oil and filter.  Pulled plugs and turned it over with a little gas coming out one plug.  Cleaned the spark plugs.  Wouldn't even fire.  Tried ether in the air cleaner.  No fire.  Tried ether in the spark plug.  No fire.  I'm at a loss, now.  I'm not a carb guy, so hesitate to even to attempt to pull that off.  Any additional ideas? 

It has spark at the plug, so wouldn't that indicate fire at the points?

No new plugs.  Cleaned the old ones real good and checked the gap.  Just seems like it should at least try to fire when I use ether.  Going to get new plugs, though, and give that a try.  Thanks, Dave

well, my plan is to get new plugs tomorrow and we'll see how that goes.  thanks for the suggestions and help.  Dave

Make sure both plugs are firing. The bad thing is you were not close to the machine when it stopped. So what caused it to stop? You know now that the electric fuel pump overpowered the needle in the carb as you found fuel in the crankcase. But why did it stop? I would start with the carb, take it apart and see that there is no junk in it. Check the float level. If nothing is found out of the ordinary, go to the points, condenser. They require attention every 100 hours. The Onans are finicky, timing also needs to be correct. After those items have been checked, the coil would be next. Also, check compression. Matter of fact check that first if you have the gauge to do so. My Onans do not like to idle for extended periods(beyond a minute), it seams they go rich on fuel as they will puff black smoke and cough until I give them some throttle. Just my 2cents.

Yes you will need the numbers listed on the left hand heat shield tag. Sandy Lake or Jacks Small engines has parts for the Onan. They are a great little engine but can be a finicky. I’m still running the stock fuel pumps on both of mine. 1,200 hours on one and 680 hours on the other and they are 42 years old. I did rebuild the pump on the 1,200 hour machine 7 years ago while I had the engine pulled so I could paint the entire tractor. Replaced the points also. A good shop should have you up and running in no time. Let us know what they find.

A carburetor kit at Sandy Lake is $118.  Is that reasonable?  Just seemed on the high side, but if it is what I need . . . .

Well, got the carb kit put in.  Had to change oil and filter again as gas had leaked into the crankcase in the interim.  Got it to fire up and sounded pretty good just sitting there.  Got it home and tried it out driving it around.  At times, it wants to spit and sputter like it isn't getting gas and has an almost total loss of power.  Other times it will run pretty good.  Guess I'll just keep using it and trying it out to see how things go.  Thanks for all of the help.  Dave

No, didn't mess with points or timing.