Craftsman FF/20 Hydrodrive Tractor Info.

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  #1  
Old 06-11-05, 02:40 PM
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Craftsman FF/20 Hydrodrive Tractor Info.

I have an old Craftsman FF/20 tractor that is in surprisingly good shape, but I cannot find manuals for it. The engine is an Onan B48G-GA020/38580, Serial # 1803529685. It is retrofitted with an electric fuel pump and has a Walbro carburator. I have located manuals for the engine and the snow thrower, but would like to find one for the tractor and mower deck. Sears, Onan, and a large number of other potential contacts inform me that the manual is long out of print and is no longer available. Anybody have any ideas?

The tractor has two problems. The first is that the battery discharges while running. I can probably fix that myself. The second is that after an hour or so of mowing in hot weather, the engine starts to missfire, backfire, and stall out. I suspect that it is a carburator float or needle valve problem, but am hesitant to work on it as I'm told the carburator is obsolete, I cannot identify part numbers on it, and parts aren't available anyway--to include Petersen Company Warehouse who bought all the Walbro obsolete parts.

Would appreciate any comments on how to proceed, to include what type of replacement carburator would work on the engine.

Thanks in advance.
JCCremer
 
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  #2  
Old 06-11-05, 07:15 PM
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DO YOU HAVE THE MODEL NUMBERS SHLD BE 1 ON TRACTOR AND THE DECK... BOTH DIFFERENT
 
  #3  
Old 06-12-05, 02:09 AM
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The shut down when hot sounds more like a coil or ignition failure, or possibly a fuel delivery problem from the tank...like a restricted cap vent.
 
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Old 06-12-05, 08:14 AM
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Sorry I forgot to give the model number for the tractor. It is Sears and Roebuck model # 917 254 820. Serial # 0451 BO1 385.

I'm unable to locate a model number or serial number for the mower deck. I'd assume that it would be somewhere on the deck housing, but examining it inside and out, I find nothing stamped in or engraved. It's obviously been repainted sometime in the past, so that might have covered it up. Where would I look to scrape the new paint off to see where I might uncover it?

On the misfiring malfunction when the tractor is hot, I've checked the gas cap cover venting (OK), checked the fuel lines and installed new filters (OK), and replaced the coil. Fuel pump is working well. No difference in running with either the new or old coils. I first suspected that it might be vapor lock in the fuel lines, but see no likely location for that to happen.

I also toyed around with the theory that bouncing around for an hour or so might cause bubbles in a partially filled fuel tank that could interrupt the fuel flow, but I tried topping off the gas tank when the misfires occurred, and misfires continued. That leads me to believe that it is likely to be a problem within the carburator itself.

FYI, I'm not a mechanic except by necessity when something isn't working right and it is fairly simple to repair.

Thanks for any advice/suggestions/help. I really appreciate it.
JCCremer
 
  #5  
Old 06-12-05, 11:10 PM
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The deck doesn't have a model# that I'm aware of, but could be mistaken.

Can you isolate the misfire to one cylinder or the other by removing one plug wire while the engine is running? Does the engine run fine for that first hour, and then start to misfire? Does this engine have points?
 
  #6  
Old 06-14-05, 04:30 AM
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The misfire virtually stops the engine, so I haven't been able to pull a spark plug wire while it is happening. After a few seconds of coughing and sputtering, it resumes running normally again until the next occurrence. I've checked both plugs, and they both are clean and dry, evidently firing equally and normally.
Yes, the engine runs normally for about an hour before an event takes place, usually on a hot day and when working over some fairly rough sloped terrain. Sometimes after a series of misfire events, it will run normally again as if nothing happened.
The engine has points, and I have the specifications for adjusting them. I've not messed with them, as Craftsman, in their engineering wisdom, has shrouded the engine so that getting access to it, and most of the parts on it, is a major disassembly operation. In short, the engine is virtually hidden within a multi-piece sheet metal envelope. I suspect that was done for air flow and cooling purposes, but it is not at all amateur mechanic friendly.
I have had the tractor into a repair shop (at significant expense, I might add) for other repairs and tune-up, so it runs well--except for this problem.
In all, I can live with the problem, but would prefer to fix it if possible.
JCCremer
 
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Old 06-15-05, 12:26 AM
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Ok, from your more detailed description, I would agree that it does sound like it could be carb related. Probably a small amount f water in the bottom of the bowl. Also, if the points enclosure had a bad gasket and got a bit of water in it, it could be turning into steam when the engine warms up and causing the misfiring. I would think this would be a problem that wouldn't go away after it exhibits itself until the engine cooled though, so the carb makes more sense (and thankfully, it's much easier to check).
 
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Old 06-15-05, 06:21 PM
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the owners manuals are not avail anymore but goto sears.com and goto parts.. put in tractor model number and you can print the pics and parts lists.... and the deck does have its own model number.. yours should be 917.253660 and there is a list of pt numbers and pics for it also....

and for engine pts and manuals try this site....

http://www.pplmotorhomes.com/parts/o...ngine-part.htm
 
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Old 06-15-05, 11:44 PM
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Thanks Bambiblaster, I didn't know the deck had it's own #. This is rarely seen on mowers nowadays.
 
  #10  
Old 06-18-05, 05:33 AM
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Many thanks, Cheese and Bambiblaster. I'll plug away at it as soon as time allows and let you know if there is any joy.
JCCremer
 
  #11  
Old 11-07-06, 12:54 AM
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Thumbs down Plugged with grass clippings - or vapor lock

I say clean out the cooling fins on the motor by removing the acres of sheet metal around the motor and the cooling vanes and blast it out with compressed air. Use a wire brush if necessary. It sounds to me as if you may be suffering from vapor lock. I have one of these mowers. It's a waste of good sheet metal around a good powerplant. I only used it to suck leaves with the attached leaf vac in the fall. Now the tranny is kaput. If I can't fix it easily - by cleaning up a stuck valve in the hydro for instance - I'm gonna pull the motor and use it on another project and scrap the rest. Good riddance. It's a horrid mower.
 
  #12  
Old 11-07-06, 03:05 AM
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That post is over a year old.
 
  #13  
Old 11-13-06, 11:38 PM
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And...

I added some info to it.

I also got my hydrodrive figured out. The gear range selector was in neutral. I didn't even know it had a neutral. So that's fixed. I know you all were rooting for me. So I've been sucking leaves today. Let the bells ring out! I'll keep you all updated on my progress since I know you'll all be in suspense & stuff.
 
  #14  
Old 11-15-06, 01:26 AM
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Exclamation Wow!

I spent the day sucking leaves! It was great, until the belt on the mower deck broke. And the recoil starter spring on the leaf sucker broke. Did I mention I'm broke?

This forum is so friendly. It's fun to post here. I've never had anyone help me with the dates on posts & stuff. It's great! I'll let everyone know how my mower repair goes.
 
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