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RodStayner

4040 Onan Issue

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RodStayner
It seems that my Onan is starting to act up lately. While mowing the last couple times, the engine would just die once while mowing. I kind of blew it off, until last night when the tractor died and it wouldn't restart. Thinking it just needed gas, I put more in the tank...no luck. The engine turned over just fine. I pulled the plugs, cleaned them a bit, still nothing. I said "heck with it" and went inside. :(! Of course, I just sold my Sunstar a couple weeks ago, and my wife was GLAD to remind me of that:) About 2 hours later, I go out and it fires right up! I am thinking that the fuel pump (it's still the original mechancial type) could be causing me some problems. I have thought about installing the electric type, but put it off since I didn't have any problems. I am on the right track or is there something else I should look at? The engine burns some oil, but normally runs just fine.

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tractormike
I have a 16 horse onan that runs very well but whenever it quits or acts up it has been a problem with the points. They usually just need a quick cleaning and away it goes for another couple of months. Years ago it had some fuel problems but I put a different carb on it and hooked up a small electric fuel pump and that solved that problem. My original carb had a vacuum driven fuel pump as part of the carb body and I had a lot of trouble with it.

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D-17_Dave
Your on the right track, but you need to identify the actual problem. To do this you need to check a few things. First crank it over and check for good blue spark. If it shows good then start the engine and pull the return tube from the tank. If the fuel pump is working well you should have a steady flowing stream of fuel returning to the tank while it's running. If not, then start looking for a restriction in the pickup tube, a weak pump, or other problems blocking the fuel sysyem. If you seem to have a good flow now then run it till it shuts off. Recheck the spark and the fuel flow. It sounds as if it's one or the other. It's cooling off now so it could help hide the fact that the cooling fins my be stopped up and the engine over heating. However with all the iron on these ONANs it's unlikely. But I would check the cooling fins for debris anyway. This should help narrow down the trouble so you can properly diagnose it. Then it should be an easy fix.

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babablacksheep
If it quit while mowing, wouldn't start, and then started just fine two hours later, it it probably the points or condenser. Condenser breaking down from heat, or points being flooded with oil. If the crankcase breather is partially clogged, pressure builds up and forces oil up around the o ring at the plunger. The ignition box fills with oil to the level that shorts the points and it quits. The oil will drain out through the gasket after it sits for a while so the engine will restart and run for a while until it happens again. Next time it quits, check spark right away. If there is no spark, crack the cover on the point box and check for oil.

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wilm169
Had the engine out of mine for a few weeks while fixing other things put the engine back in and will not start, checked points good spark, checked netural wire has good power and brakes, checked plug no spark, no spark out of coil. AHH HAW found the problem bad coil I assume.

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RodStayner
I do believe that my heat shields are in place. Hopefully I'll get to check it out today or early next week. I'll check for good spark and go from there... Thanks for all your help!

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Guest
Buy an electric pump from CarQuest. Part number: CPF 41501.

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aleman77x
I have been thinking of converting my 4040 to an electric pump (looked into it $37 from my local CarQuest store). How difficult is the switch? I wasen't sure where to start, I have a repair manual and CCKA manual, but need some help. I was looking for an old post , but couldn't find one. Any info would be appreciated.

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ambler
Could be the coil too. Check to see if you have spark when it stops next. Heat could be causing the coil to fail. Something in the laminations. Points and condenser wouldn't fix themselves. I hate intermittents.

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joeMA
rod i would be int. in knowing if you resolved your issue with int. shutdown, this is how my 4040 was acting all summer , had to use it for shorter periods each time until finalyparked in garage joinrd this club and began search for answers. in meantime snows about to fall , had to buy J,D. 140 and power ang. plow and hope its strong nuff to plow mr out. i am finally under impr. that my main bearings have tightened right up solid. i used to be able to lock elect. clutch and turn by hand , or small wratchet on pulley nut but now starter will hardly move and cant turn much. thanx.joema

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mikeb
Rod, I was troubleshooting a similar problem this past weekend on my powrmax loader. Would run fine then just stop. Because it stopped so abruptly, I thought electrics first, not fuel. Pulled a plug, no spark. Checked the hot side (+) of the coil with a test lamp (key on), no 12v. Wiggled the ignition switch, instant 12 volts to the coil: ran fine for a while then stopped again. Wiggled the ignition switch and it started right up again. Obviously I have a bad connection either inside or outside of my ignition switch: could be corrosion, could be those damn crimp connectors, could be internal to the switch. Something else for you to consider! :) Good luck troubleshooting and keep us informed of your progress. Mike Bennett Fresno, CA

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