Tecumseh OHM90 9hp problems?

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  #1  
Old 11-21-06, 04:55 PM
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Tecumseh OHM90 9hp problems?

I have two polaris go karts with 9hp tecumseh motors on them. I changed the oil to 5w-30w for winter months and took one of the carbs off and cleaned because it was not running to good. Now it will die as soon as I depress the throttle. I put a new seat in the intake as the old one looked bad. I did not change the center gasket between the bowl and the carb. Could this cause the motor to die when pushing the throttle? It sound like the motor is flooding itself out? Any help is appreciated. Thanks Ron
 
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Old 11-21-06, 05:41 PM
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that is usually a good indication that there is a problem with the low speed circuit in your carburetor, it is probably not getting enough fuel when you throttle the engine and it dies. Check and make sure all the welch plugs are in place and that jets are clear.

What is the spec number off your engine
 
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Old 11-21-06, 06:35 PM
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The numbers on the motor are Engine model# OHM90 222302A Engine family YTPXS.3182AA Displacement is 318.
I have never seen a carb like this before. When you take the bottom bowl off(which is held only with a wire) there is a float, a pin, and a rubber seat that sets below the pin. It has one jet with a rubber ring on the bottom which set atop a spring. There are no adjustments and not many parts that I can see that would cause this. I am confused. I thought for sure the rubber seat would have taken care of the problem.
 
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Old 11-21-06, 06:44 PM
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Also the motor ran ok before I cleaned the carb. It was hard to start before so I took the carb apart and sprayed with carb cleaner and blew compressed air through out the carb. I put it back together with the new rubber seat below the pin and now it starts but as soon as I touch the throttle it dies. I cant even slowly depress the pedal to get it to move without it dieing. So something happened when I took the carb off to clean it. I assume the gasket between the bowl and the carb needs to be replaced. I am not to smart when it comes to this stuff. But I can usally fix about anything.
 
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Old 11-21-06, 08:30 PM
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On the side of the plastic float bowl there is a drain screw, remove this screw, there will be a small spring behind it, there is a plastic jet in there and behind the jet is another O-Ring that seals up against the jet. This O-Ring will swell up and close up and fuel will not flow through it. Inspect this O-Ring and if looks more like a flat rubber washer then an O-Ring, Replace it and see if that does not take care of your problem.

I have also had the welch plug come out of the side of the aluminum part of the carburetor, this plug covers access to the low speed jets on this carburetor, without this plug in place the engine will not run right, so make sure this plug is still in place.

Best of Luck....
 
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Old 11-21-06, 08:50 PM
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Thanks for the information. I had that plastic jet out and the o ring seemed to be ok. I will check those plugs. Its just weird that it ran fine before I cleaned the carb. It was just hard to get started before. Once started it ran fine. That rubber seat has a groove on one side. I assumed that the groove faced down.
 
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Old 11-22-06, 06:01 AM
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Smile Groovy Seat

If the seat had a groove in it, then it should be replaced. It should look like an O-ring, and in fact is identical to the one that is on the nozzle (same part number). When they get that groove in them they flatten out and can restrict fuel flow past them. When you look at this seat when out of the carburetor, it is not under any pressure, but once installed the spring applies pressure to it and it can flatten out even more cutting down fuel supply. Also if the O-Ring that is around the bottom of the nozzle is not sealing good, fuel will not be drawn up the nozzle as it should.

Make sure the float bowl gasket is in the proper position as the low speed circuit feeds up through it.

You can look at a parts breakdown for your carburetor at this site

http://www.partstree.com/parts/?lc=tecumseh&mn=640289-TEC&dn=10CA181640289-CA

Reference # 47 is the welch plug and # 37 are the O-Rings I am making reference to.
 
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Old 11-22-06, 06:12 AM
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The seat that I replaced is the one under the float pin were the gas first comes in. This seat was new and the mechanic at Rigg's said the groove goes down. This groove is there from the factory.
 
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Old 11-22-06, 06:19 AM
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Ok. I see the problem now. Thanks for the website. My carb does not have the main jet, spring or o ring. No wonder it did'nt work. Thank you so much for your help.
 
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Old 11-22-06, 06:31 AM
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Good thing you saw what I was talking about, otherwise I bet I was not making much sense. Yes, the seat for the inlet needle does have a groove in it and it does go down. Over a period of time the O-Ring by the main jet will flatten out and develop a groove in it also from the pressure of the jet resting against it, that is what I was talking about.

Best of luck...
 
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Old 11-22-06, 07:03 AM
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I think a overhaul kit for that carb is less than 20.00, it includes the entire bowl assy.
Can't recall for sure now but I think I had problems finding individual parts...?
 
  #12  
Old 11-22-06, 02:46 PM
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Talking

Alright were up and runing again. The local Rigg's (lawn supply) had all the parts by each. So I installed them just a few minutes ago. And I played with the speed a bit to see how fast they will go. I was impressed. The adults will have fun as well as the kids. I just bought these and the kids have not even driven them yet. Mostly because of school, basketball and swimming team. But they will be off for Thanksgiving and guess what they will be doing all day. Happy Thanksgiving everybody. And thank you for your help. Great site.
 
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