[chasemillie]

I have a craftsman lawn tractor 24 hp mdl #917275684 that starts and runs fine until its warm then it will start to serge and stuter until it dies. If you let it set for about 3 to 5 minutes it will restart and then go through the same thing again in about 10 minutes. Any help would be great thanks

[ballengerb1]

Next time yopu get it to die try testing for spark immediately. Even though you know it is not going to start lets see if there is spark at the plug.

[Fog22you]

Hello,

My Craftsman tractor just started doing the same thing. Fuel line, filter, tank, carb etc cleaned and check. New plug. Dies after it warms up. Will restart immediately, but will not continue to run. Did the spark plug fix your problem? HELP! Grass is over a foot high.
Thank you

[ballengerb1]

I think bth you guys may have a bad coil that is over heating.

[chasemillie]

Found it. Engine wire harnes. Two diodes in the harness buy the carb in some black tape. Wires are the kill wire to shut off the tracker the diodes overheat and kill the mower. To test unplug the wires and mower will run for ever. However you can't turn it off unless you run it out of gas or touch the wires back to where they belong. Wire harness sears parts direct $100.00.

[sparkyguy545]

I also have a Sears Tractor #917.273372 (17.5HP) that suddenly has the Same problem. My schematic in the Owner's manual doesn't show the diodes you are describing. Does anybody know if they are on all models or just the model that Chasemillie has.

[crigby]

Hi,
No diodes are only used on certain models of certain brands. Their purpose is two-fold, but is to prevent voltage polarity/current flow in the wrong direction, and is there to protect the ignition modules if certain equipment is present.
The most common culprit for running 10 minutes and shutting down is fuel related. Either the fuel filter clogged or the fuel pump not able to keep up.
Peace,
Clarke

[sparkyguy545]

Interestingly, mine is small enough there is no fuel pump, the fuel line is only 12" long, and I've blown it out. The filter is new (I was hoping it was the problem), and the tractor is only about 18 months old. The butterfly & choke are as clean as new (I can see them with a flashlight) with filter removed. Compression is the same when Hot & Cold, which would tend to eliminate bad valve seating issues since it runs like a swiss watch when cold and for the first 30 minutes or so. Then it sputters & dies COLD. Since it runs so well for 30 minutes (doesn't even misfire) I can't believe the muffler would be clogged. Plus it's only a year and a half old. Minimal visible carbon on muffler. After dying, it sounds like there is zero spark. However, there IS spark, I just can't tell if it changes between hot & cold. After waiting for 15 minutes or so, it again runs flawlessly, then will sputter & die flat again. I need to cut my yard in two sessions, knowing it will die at the same approximate location each time. Wait to cool, then start again. I'm leaning towards suspecting that the coil is getting weak/bad when it warms up. There just isn't much left. I'm a gear-head from the '60's, and rebuilt my share of auto engines, but this simple one-lunger has got me stumped. If it has gas, air, compression and spark at the right times it HAS to fire, right.. . Wrong!

[crigby]

Hi,
I would tend to agree at the 30 minute mark that it is probably the ignition. Anything below 12 is definitely usually fuel. 12-15 is iffy. 15-20 is moving toward ignition as the cause. Above 20 has ignition as the prime candidate.
Peace,
Clarke

[sparkyguy545]

After an INSANE amount of time and testing, I eventually found it was the (almost useless) solenoid on the bottom of the carburetor bowl. It is SUPPOST to stay open while running and close only when the engine is stopped. It's function is to starve the engine of fuel when it is stopped. As a temporary test, I removed the solenoid, and plugged the opening with a short 5/16-24 (fine thread) bolt. (Careful if you do this because the fuel will continuously dump out the bottom of the carb unless you first disconnect the fuel line.) After this, the engine ran like a top and did NOT die after getting warm. In fact, it hasn't died once since then. Solution in my case.. . Replace the fuel cutoff solenoid. (About $50) If you need a quick, temporary fix.. . Pull it out and throw it away (also cheaper), but I'm sure not recommended by the mfr. Apparently, some solenoids will "open" when they get warm. Since they operate in a "fail-safe" mode they go to a "closed" position when turned off, or if they lose power. Lay-man's description.. . When the solenoid gets hot it will fail. This cuts off the fuel supply and the engine dies.

[crigby]

Hi,
If you do not want the expense or fallibility of the solenoid, replace it with part #691657 on that engine.
Peace,
Clarke

[sparkyguy545]

I was a bit concerned that permanent removal of the solenoid might cause premature wear problems with the float seat, since it would always have the upstream fuel pressure on it from the carb up to the fuel tank. On my tractor, it's only about 12" since it doesn't have a fuel pump. Therefore, I elected to actually get a (way too expensive) replacement solenoid. Probably a waste of money, but I was sure it would work. I searched a dozen Internet forums with this problem, found LOTS of similar complaints, LOTS of suggestions, but interestingly, none of the sites I looked at mentioned this #$%^$$ solenoid as a cause of problems. I only found it by eliminating everything else. Eventually, I realized that when it started to die, it still had good spark (I previously replaced the coil), I also replaced fuel filter, air filters, fuel hose, spark plug, checked compression (both hot and cold), verified the solenoid did NOT lose power when the engine died, disassembled carb float and seat, and I can't think what else. I ultimately noticed that when it died, it did so VERY quickly, and it die NOT act rich (no sudden black smoke) and the spark plug did NOT look wet or appear running rich. In my Ah-Ha momemt I concluded it MUST be getting starved for fuel. Without a fuel pump, I realized what that stupid solenoid actually does (how it functions) and concluded it was the ONLY thing that could possibly starving the engine of fuel. Therefore, REMOVE IT. I was a bit worried it might backfire on shut-down, but that didn't even happen. Basically, it appears worthless, except for my comment about fuel pressure on the float seat that I noted above. Sorry for the long post, but this was a HUGE problem for me to analyze (dozens of hours of trial and error). I've also talked to a few neighbors that have spent hundreds of dollars having places replace a host of other components and finally give-up. I just hope this helps others.

[crigby]

Hi,
The solenoid really has one purpose; shutting off fuel flow during the shutdown cycle. When the switch is turned off and no ignition is present to burn fuel, the engine is still spinning and the carb is still mixing gas with air. This unburned fuel/air mix can enter a hot engine or muffler and be ignited causing a backfire which OHV engines are particularly susceptible to having resulting damage from in the valve train.
Without one just idle the engine for 20 seconds before shutdown.
If you think your situation was time-consuming, try some of the commercial equipment with a few relays in the system where the solenoid shuts because a relay opens because of a bad switch somewhere in the safety circuit (Deere's Z-Trak had this going on for a couple of years so you had to know what serial numbers were affected.)
Peace,
Clarke

[sparkyguy545]

Agreed. I'm not into tearing down small engines, but I am a professional engineer and I've been a very avid "gear head" and drag racer as a hobby since the '60s. Figured, I've torn engines down, rebuilt them, hot-rodded 'em, etc. This tractor has just ONE cylinder with basically NO ignition (essentially a magneto & permanent magnet). If you mix correct amounts of air, gas, compression & spark at the right time and it MUST fire, right?? Well, kind of right.. . I guess 'm just not used to looking for stuff like a solenoid on a carb bowl on small-block Chevy's.. . But that's another story entirely. Hope someone else saves some time reading all this. Best wishes.

[paulydek]

5/16-24 (fine thread) bolt... part #691657... 50 dollar replacement solenoids...

All these options were either more time or money than I cared to spend. So I simply grabbed my wire cutters and snipped the plunger shaft off. Plungerless solenoid reinstalled, idle prior to powering off, and the mower is running like a top again.

[leroylucas]

I need to know how to set the valves on 17.5 briggs engine

[leroylucas]

What is the valve setting for briggs and Stratton 17.5 engine

[leroylucas]

What is the valve setting for briggs and Stratton 17.5 engine

Have to spin flywheel to start engine

[crigby]

Hi,
Perhaps the YouTube video would be instructive at:
Lawn Mower Repair Valve Adjustment - YouTube
Peace,
Clarke