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mike_sdak

917 choke problems

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mike_sdak
Hello everyone. I posted last year in regard to my 917 Allis, with the kt-17 kohler engine. It only runs on full choke. Now, being a bit of a procrastinator, I am dealing with the problem again this summer. Last year, I ran a tank of gas with carb and choke cleaning additive through the engine. That didn't help. I also added a new fuel filter, a replacement for a modern briggs engine, made by mtd, I think. If I recall, the posts in response to my message included some suggestions like, 1. check gas tank screen 2. maybe worn throttle shaft 3. tighten screws on manifold Any other thoughts? I notice the fuel filter never fills entirely full, maybe 80-90 percent, with a bubble at the top side. This should be totally full, shouldn't it? Could the fuel filter be restrictive? Thanks <again> for any help you may offer.

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mike_sdak
The gas cap should be ok - I removed it, and it didn't change the situation. I have not checked the manifold gasket. The previous owner mentioned tightening <I think> the fuel pump mounting screws to help it with a similar problem a few years ago. Maybe it is a gasket problem?

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HubbardRA
I think that most likely you have a major varnish build-up in the main jet of the carb. Carb needs to be taken apart and the jet cleaned. That would be the first thing I would do. I have run into this a lot with the fuel we have nowadays. There is no way this will clean itself by running it. Anything you put into the tank and can still run the engine, is not strong enough to remove the varnish buildup once it hardens.

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npalen
Another thing you might check is the looseness of the throttle shaft where it enters the carb. The one on my Onan CCKB was pretty sloppy so I slipped a 1/4" ID oring over the shaft with a light compression spring on the shaft also to hold the oring against the side of the carb hopefully preventing air leak. I can post a picture of this if you think it might help. Nelson

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mike_sdak
a brief update, after tearing a few things apart: 1. The gasket between the fuel pump and the block was broken and leaking. However, I only think this caused it to leak oil. 2. The manifold gaskets, on each cylinder, are permatex or silicone. I didn't take the manifold off, yet. I would like to try other avenues first. However, if the permatex was applied properly, I wouldn't think the gasket would degrade with time? Maybe I should pull it off anyway, and replace with kohler gaskets, I don't know. 3. Is it possible the fuel pump would be getting weak? I also added a fuel filter, as mentioned before. I don't know if this would be restricting flow, possibly? I don't think a fuel filter was factory installed. I am considering just replacing the fuel line with a length of new fuel line w/o a filter. 4. I pulled the gas tank off to look at the fuel screen. I didn't see one, but it looks like the o-ring on the bung fitting is shot. I don't know if this would contribute to the problem. Am I correct in assuming an air leak in the fuel line wouldn't cause my problem? 5. There was a little play in the throttle shaft, I don't know how it compares to a new carb. 6. The more I think about it, It may be varnish in the carb. jets, as HubbardRA mentioned. I hate to pull it off the engine. However, it may be my best shot at the problem. Thanks for any thoughts you can offer.

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tec2484
quote:
Originally posted by mike_sdak
2. The manifold gaskets, on each cylinder, are permatex or silicone. I didn't take the manifold off, yet. I would like to try other avenues first. However, if the permatex was applied properly, I wouldn't think the gasket would degrade with time? Maybe I should pull it off anyway, and replace with kohler gaskets, I don't know. 4. I pulled the gas tank off to look at the fuel screen. I didn't see one, but it looks like the o-ring on the bung fitting is shot. I don't know if this would contribute to the problem. Am I correct in assuming an air leak in the fuel line wouldn't cause my problem? 5. There was a little play in the throttle shaft, I don't know how it compares to a new carb.
Most permatex and silicone won't hold up to the heat of a cylinder. Some of the o-ring may be hung up in the main jet. With it running try spraying carb cleaner around the shaft and see if the engine sounds different.

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mike_sdak
Thanks for all of the guidance, it has helped a lot. Another update: I replaced the full length of the fuel line between the tank and the carb., with no filter at all. I also replaced the fuel pump-to-block gasket with hi temp permatex. I re-gapped the spark plugs to .025 (they were at, maybe .040). The engine now runs strong at full throttle, with no choke. However, it still exhibits two problems: 1. Hard starting, and, 2. short-lived Periods of surging/coughing/backfiring every 5 minutes or so when at full rpms. I think I might have a batch of bad gas? It reminds me of running year-old mixed gas (leftover from an outboard) in a farmall H when I was young - it exhibited the same periodic sputtering. Thoughts?

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mike_sdak
An update: I removed and cleaned the carb, replaced the manifold gaskets, carb. mounting gasket, and any other damaged gasket I found. It runs like a champ. Thanks to all who replied, I can now catch up on my mowing. PS: With the engine running so well, I broke the mower drive belt when cutting heavy grass. Does anyone know the proper terminology and size for this belt? I checked the guides on this site, and a simplicity belt guide, but I find conflicting numbers. The belt goes from the PTO clutch to the mower deck. Is this the "cross drive" belt?

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