Been searching but haven't found an answer to my problem. Craftsman twin 17hp rider Model 917.2559105 and has no spark. Found that I have a bad clutch switch so I jump that trying to get the engine started. Engine turns over fine but no spark to the plug, well sometimes it does and most of the time it doesn't. I have tested the solnoid and put on a new carb. The orginial carb didn't have much gas in the bowl when I took it apart to check the float. I got the mower to start one time and it ran for about 2-3 minutes then died.
Does anyone have any ideas?

Remove fuel line, place end into jar and see if gas flows freely.
I have seen no fuel give the impression of no spark.

Hi,
You have one too many digits in the model number! Leaving off the final digit, I get an 18HP garden tractor with a 3-speed transaxle that has high/low ranges. Sound like yours?
To the left of the air cleaner on the blower housing there is a threaded post with a wire plugged to a spade connector. Unplugging this will isolate the engine from the frame, and you can check the engine to see if it is the problem.
One of the most common problems with this engine is the fuel pump that is built into the carb. The bad thing is the way the engine is turned in the application. The flywheel/screen face rearward and the pump is above it. Three small bolts with either 1/4" or 5/16" heads were used to hold it together. Lots of small pieces in the kit including two very small springs. Can be a pain.
B&S part #393397 for engine 422437 0721-01.
Peace,
Clarke

Hi Crigby,

Weel the model number is off the front cover, digit for digit. Its also a 6 speed transaxle.
The carb is getting plenty of fuel as you can take the line off the carb and turn the engine over and gas will really pump out of the line. There is a pump located on the rear heat shield that pumps the gas to the carb. I changed out the carb figuring that the old one might be gummed up. I had the new one on hand and it was faster changing it out that trying to clean out the old one at that monment. The problem still might be with the solnoid or a switch. Need more information on how to check these things.

Thanks for your answer, I'll look for the threaded post

Hi,
Well, Sears and no cross-reference I know of has the slightest idea what to do with a Sears model number of 10 digits. They are generally 3 digits for the vendor (manufacturer) and 6 digits for the exact machine. Go back before into '70's, and before, and they have one less digit.
Got some engine numbers? Single or twin cylinder? Some of the machines have some unusual things done in the grounding circuit, but it takes a schematic for me to "see" it.
Peace,
Clarke

Switch can be tested with a continuity tester, or a light and a bulb.
If a fuel solenoid. You want to apply 12 volts to solenoid coil and see if fuel flows.
Keep Sparks and fuel separated.

Crigby,

Engine number is 422437, type 1281-01
Twin 18.0 HP IC electric start 44" mower, garden tractor
I am tending to believe that I might have a shear flywhell key. From the way that it acts sometimes a spark and sometimes not. I think it might be jumping time. Does this sound possible?

Thanks
Deerrack

A timing light will tell when it fires, if sheared, timing marks will show iratic.

Hi,
I show that no points were ever used in that particular engine. I do show that the old style armature was used on the first production of the engine which means that the separate magnetron was added to it.
You can look at the armature itself to tell in a number of ways. A points armature will have two legs for the coil spaced about 1/2" from the windings on both side and a black sheathed wire (the sheath is plastisized asbestos with a shellacked copper wire within) proceeding under the flywheel. The early Magnetron unit will have a white (generally) plastic trigger unit in one side of it. The unitized armature will have the black plastic extend nearly to the edge on one side (in the direction of rotation of the engine it will be on the side that the magnets sweep by first.)
A sheared flywheel key will cause a lack of fire completely almost always in a points machine, fire at the wrong time in a Magnetron machine.
The armature is under higher stress in this engine since the armature fires both plugs every time the piston comes up. This is common in Briggs and Tecumseh engines and si called "rascal" timing. They do not make power every time, but the design is simpler.
If you have isolated the engine and the fire is still intermittent; replace the armature with #394891.
I am a firm believer in finding out what is at fault; I always try to eliminate parts when I am not able to go right to the offending part, test and verify.
Having been at for over 35 years and subsequently trained and certified at electronics; I can tell two things drive you "nuts" and that is electrical troubles (especially if there is more than one) and one problem that gives a symptom that leads you to correct it (correctly) but leads you to another. I have seen four things fail at once in a very complicated piece of equipment. ( and I still have a pretty full head of hair.)
Peace,
Clarke
PS Thought about telling a story, but it was not quite apropos.