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Discussion Starter · #1 ·
Olcowhand already knows of my issues I am having with the Onan but we still haven't gotten it figured out. When I first put the Onan Performer 20hp in the 1655 it did great. Then with all the tractor shuffling we have been doing I had it setting outside for a couple days. Of course those couple days is when we were getting hammered with rain. The problem with that is the gas tank/fuel level cap is missing the plastic lens and it acts basically like a funnel for the water to get in to the tank.

Ever since it sat out is has been acting up. There wasn't that much gas in it and I added a little dry gas to help disperse the water that might have gotten in. I figured I would just run the gas that was left out of it and then refill with good gas and not park it outside anymore.

I used the 1655 a good bit yesterday with loading mulch in the garden cart my wife was towing behind the Massey 12H. It was driving me nuts and I finally had enough and was bound to fix it. The symptoms are it idles perfect, once in a while it will sound like it misses at idle but not too often. When you rev it or put it to full throttle it misses a lot more, sounds just like it is running out of gas. It gets even worse when it is under load ie; lifting the bucket or driving around.

So I finally had enough and pulled it in the garage, pulled the carb off and cleaned it completely, also blew air through all of the passages to make sure they were all clear. The float height was set really low and I set it to specs and I thought for sure I found the problem. Put it back together and still the same thing.

So this time I took the carb off again and cleaned it again just to make sure I didn't miss anything. Didn't find anything other then just cleaning it for the second time. Put it back together and it is still acting up.

So now I figure the 3rd time is the charm and it has to be something either with the fuel filter or the gas tank. I pulled the gas tank off and drained it, pulled the petcock out and took that apart and cleaned it as well. The petcock did have some crud in it so I was hopeful that was my problem. While the carb was still on the engine I fired it up to run that last of the gas through the line and bowl. While it was running I checked the line on the inlet side of the fuel pump and it had pretty good suction, granted I didn't hook up a vacuum gauge.

With the fuel lines being ran empty, I pulled the fuel filter off and replaced it with a piece of straight hose line to splice the hoses for the time being. I pull the carb off for the 3rd time, I figure why not because now I have it down to a 5 minute job. Triple checked everything with the carb and still didn't find anything unusual. The only thing that I couldn't do was remove the one welch plug because I didn't have a replacement. So I put it all back together and still the same thing.

At this point in time I am ready to yank the Onan off of it and chuck it or take a sledge to the carb. I know it is going to end up being something simple and I will wanna kick myself in the arse. After this last time, I pulled the spark plugs to make sure it was firing on both cylinders and the plugs looked great, almost on the lean side, would like to see a little more tan color to them. I did notice that when the engine is running and you rev it up the fuel that would come out of the emulsion tube(don't really know what it is called) kind of just dribbled. I don't see how the dribble would atomize correctly.

Anyway that is my saga, I am going to replace the fuel pump with a spare I have even though I am pretty sure the fuel pump is good. Is there something else I am missing? The engine fires right off, faster then it ever has. I know it is fuel related, for some reason though I just haven't gotten it.
 

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Red Tractor Nut & Diesel Addict
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Does choking slightly help in any way when it starts this George? If not, you may wanna put a timing light & watch the strobe for any breaks in the light. Could be an erratic spark. Coils going bad will do fine at idle, then break down at anything higher. I know it sounds like fuel to me also, but won't take but a minute to check for erratic spark.
 

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Electric Tractors
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I have the same problem with my neighbors WH 16hp Onan. Gas cap broken when it rains water gets in, tractor sits outside all the time. His surges won't run smooth without the choke on. Last spring solved the problem by cleaning the main jet out with torch tip cleaner and some spray carb cleaner, was able to do this without removing the carb from the engine. Just pull the top off, all the shrouds that are in the way of the drain plug on the carb and cleaned out the jet without removing it. Worked great got a smooth running engine at all speeds and loads on it. Now it's gone back the same way again so time for another cleaning.
 

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George, Does your Onan have points and condensor or is it electronic ignition? The Onan in my Sears will drive you nuts getting it to run if it gets left out in a rain. The vents in the hood allow water to drop down on the ignition cover and it becomes very hard to start and run well until it is completely dried out.
 
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Discussion Starter · #6 ·
I am pretty sure it is electronic. Only weird thing is it has a condenser on the negative side of the coil. I would think with electronic ignition you wouldn't need the condenser?

I will put a timing light on it and see if the light breaks up at all. At least if anything I can definitely rule that out. When it was sitting outside it had the hood on so water couldn't really get on the engine itself. The thing starts right up, I haven't tried choking it partially to see if it improves the stumbling.

I also used my air gun cleaning brushes to clean out any orifices I could fit them in which includes the main jet. I used to have a set of torch tip cleaners but I can't find them. Will have to get another set.
 

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Red Tractor Nut & Diesel Addict
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The P series are all electronic ignition. I have only dealt with one P engine with ignition problems, and it was only affected at higher rpm's. It would cut out only a little bit though, then shut off like you turned the key to off. Just thought as you said George, to use the light just to definitely rule ignition out.
 

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Do you have new spark plugs in it?
IMO unless the gap is bridged, cleaning old spark plugs doesn't work,
sometimes drying them off helps but usually a plug that is too wet engine won't fire at all, yours is running.
 

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Discussion Starter · #10 ·
The plugs are in great shape and dry. They are burning clean and there is no wetness on them at all.

I just came in from putting the timing light on one of the cylinders. It is definitely something with the ignition/coil. It is doing the missing/roughness at idle today now. While it was sitting there idling, when it would miss you could see an irregularity in the timing light. I have a spare coil which I am going to try. The thing I don't understand is why there is a condenser on this engine? I just went through the manual and there isn't anything shown about a condenser? I am wondering if I should remove it or keep it?
 

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Discussion Starter · #11 ·
coop said:
does it run good cold? or does this problem exist in all temps?
All temps. Engine cold or engine hot.
 

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NUTNDUN said:
The plugs are in great shape and dry. They are burning clean and there is no wetness on them at all.

I just came in from putting the timing light on one of the cylinders. It is definitely something with the ignition/coil. It is doing the missing/roughness at idle today now. While it was sitting there idling, when it would miss you could see an irregularity in the timing light. I have a spare coil which I am going to try. The thing I don't understand is why there is a condenser on this engine? I just went through the manual and there isn't anything shown about a condenser? I am wondering if I should remove it or keep it?
Disconnect the condenser and try it, what do you got to loose.
 

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Red Tractor Nut & Diesel Addict
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I'm not sure if it's an actual condenser, or a suppressor for radio signals. If just a suppressor, you could remove it, but not knowing, I wouldn't run it without it.
Are you SURE it's an electronic ignition coil? The replacements for the old points style coils look pretty much the same.
 

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Red Tractor Nut & Diesel Addict
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George, in my pdf service manual, in the schematic, it shows it to be a condenser, so you need to use it for sure.
 

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Discussion Starter · #15 ·
Alright, why is it that you know yourself to check the simple things first but you never do it that way? I am going to go beat my head on one of the trees I cut down yesterday until it is permanently embedded in my brain. I went out to start removing the condenser and here the positive side was loose. I pulled the nut off and put a lock washer on, started it up and she is perfectly fine.

Time to go beat my head....
 

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Discussion Starter · #16 ·
I wanted to say thank you all for your help. I am glad that it did turn out to be something simple. The timing of events I think is what made me go directly to the carb. I still should have known better.

Back to beating my head....
 

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What kind of gpark plug wires go yous guys use, the coil on my 16 hp has pins that stick into the wire while my 24hp performer has regular type ends on the wire
 

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NUTNDUN said:
I wanted to say thank you all for your help. I am glad that it did turn out to be something simple. The timing of events I think is what made me go directly to the carb. I still should have known better.

Back to beating my head....
Glad you got it solved and banging your head on a tree hurts, I know.
 

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Discussion Starter · #20 ·
coop said:
What kind of gpark plug wires go yous guys use, the coil on my 16 hp has pins that stick into the wire while my 24hp performer has regular type ends on the wire
There are two different types that were used. The Onan 16hp that was in the 1655 when I got it had the coil with the thread on where the wire just stuck out a little to make contact. The B48 that was in a Case 448 and the Onan Performer 20hp I have in the 1655 now had the regular automotive ends on it. It all depends on the coil.
 
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