Craftsman tractor intermittent start problem

sumdumgaiOctober 7, 2012

I've got a Craftsman 917.255470 that intermittently won't start. Sometimes when I sit down on the seat real hard, it'll start. Sometimes when I push up on the mower engage lever and let it slam down, it'll start. Sometimes when I just push the tractor a few feet, it'll start. Very annoying. Manual says there are three safety switches: Clutch/Brake (pedal up), attachment clutch (clutch off) and seat occupied (not occupied). I don't think it's the seat occupied switch. Where are the other two switches located and how can I test them? Thanks.

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rcbe(6)

to start your machine, you want the clutch/brake pedal full depressed; the seat switch depressed by your body weight; attachment switches/levers set to off; throttle cracked 50% (if a separate throttle); choke on ( if engine is cold).

If you have short legs, be careful not to slide too far forward during start to allow the seat switch to disengage.Or, if you don't weigh that much, try adding an extra weight behind you on the seat during startup.

If it still cuts in and out as described, try replacing the seat safety switch. Of all the posts I see here on craftsmans with similar start problems that is the most common cure.

    Bookmark   October 7, 2012 at 2:11PM
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mownie(7)

Please clarify what you mean by "won't start".
To some folks, cranking and starting are the same thing, but that is erroneous.
Cranking is the turning (spinning) of the engine that must be done in order for the engine to start.
Starting is what happens the first moment the engine begins to run of its own volition (and cranking ceases).
On your tractor there are in fact 3 "safety switches"
Of these 3 switches, only the attachment clutch switch (mow deck switch) can affect both Cranking and/or Starting.
The foot brake switch can affect Cranking (but it has no influence over Starting/running.
The seat switch on your tractor influences Starting/running but has no influence on Cranking.
If your engine CRANKS but will not START, the foot brake switch is good and that leaves the deck switch or the seat switch as the suspects.
Deck switch has 2 White wires and 2 Black wires serving it.
The 2 Black wires are the ones that affect Start/run.
The 2 terminals on the deck switch that have Black wires must be tested with an Ohmmeter or a continuity tester.
Test results for a good switch will show that there is continuity through the Black terminals when the deck is down, but no continuity when the deck is up.
If the deck switch shows continuity no matter if deck is down or up.............either the switch is defective or the operating linkage/mechanism is faulty or out of adjustment.
If the switch tests OK, then the seat switch is where your problem lies.
And the seat switch has a "shorting connector" built into the plastic connector body and thus will act like an unoccupied seat condition if the connector is unplugged from the seat switch.
If all teste point to the seat switch make sure that the seat switch operating linkage/mechanism is actually operating the switch far enough for the switch to open when the seat is occupied. Adjustment disorder is a fairly common thing to find with seat switches.

    Bookmark   October 7, 2012 at 2:25PM
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sumdumgai

To clarify, when I turn the key, nothing happens. When it works, I can actually start the engine while standing beside it (blade of course not engaged, brake pedal out, and with the little level below the mower engagement level up and set in place). In other words, I don't have to be sitting on the seat to start it. But when this 'no start' condition happens, it does not matter whether I sit on seat or stand - turning the key results in nothing, no crank, no starter solenoid click, nothing - as if a completely dead battery (which it is not). I'm not sure if the seat swith is supposed to act this way (start without being seated), but I don't think it is the problem. Some other switch must have a bad or weak contact because when I slam down on the seat or let the mower engage level slam down, it eventually starts.

    Bookmark   October 8, 2012 at 6:59PM
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bill_kapaun

You might want to go to searspartsdirect.com and download the manual for it.
Looking at the schematic, you'll see the ONLY thing on it that will click is the starter solenoid.

You simply have to trace the circuit from where the SMALL RED wire connects to the Battery + stud on the solenoid.
Then through the fuse to the "B" terminal of the key switch.

When in the start position, "B" is connected to the "S" terminal of the key switch.
Voltage then travels through the clutch/brake switch, then the attachment switch to the SMALL terminal of the starter solenoid.

A 12V test light would be IDEAL for this circuit.

    Bookmark   October 8, 2012 at 9:42PM
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sumdumgai

Can you tell me where the attachent clutch switch is located and how I would get to it? Thanks.

    Bookmark   October 15, 2012 at 8:42PM
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mownie(7)

Where mowers have a deck engagement lever assembly that mounts directly onto the deck, the deck switch typically is mounted on the deck and situates into the lever assembly parts on the deck.
Where mowers have an engagement lever that is mounted on the tractor and has linkage or a cable going to the deck.........the attachment clutch switch is typically mounted on the tractor and situated near the engagement lever linkage. Looking at the IPL it appears that your switch is going to be on the tractor and not on the deck itself.

    Bookmark   October 16, 2012 at 12:53AM
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bill_kapaun

Follow the WHITE Wire

    Bookmark   October 16, 2012 at 2:05AM
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bluemower

Here is another possibility. The ground wire for the starter solenoid is bolted tight to the frame, but is not making good continuity. On some of these, the ground wire is located on the rear of the mower, just inboard of the right rear tire. Reach over the tire with a wrench and loosen / retighten the bolt that connects a wire to the frame.

    Bookmark   October 16, 2012 at 9:49AM
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henhill

I have the same kind of problem- but now it won't start at all.(it does crank and every other thing has been eliminated as the problem) I even hired someone to come by, but they couldn't figure it out, either, except they said that there seems to be a short somewhere. I pulled a full wiring harness from another similar Craftsman that I use for parts, and when he switched out the ignition switch to this one, it fit the harness, Do you think it is worth trying to replace the harness with one pilfered from the other tractor? A by-pass of the kill switch failed.

    Bookmark   August 9, 2014 at 10:21PM
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bill_kapaun

There's a lot of ignition switches that have the same pin arrangement but differ electrically.

Look at the Owners Manuals for both tractors and see if the harness has the same part#..

I wouldn't replace a harness unless there was obvious damage.
I'd hone my troubleshooting skills.

Not sure why you say you have the same kind of problem?

    Bookmark   August 9, 2014 at 11:11PM
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henhill

I said that because starting was intermittent until one day it stalled and never started again. I went through the bulk of the "list" above, but nothing. I hired someone who said he thought it was an electric problem: there was a short causing something to kill the current before it starts. He tried to bypass it and installed a manual kill switch and an on/off for the gas line. We also switched out the ignition with the one from the other tractor. (It is much newer and a Briggs, not the Kohler) It started a few times and then wouldn't again. I figured that because I have been able to exchange the ignition that maybe I could exchange the whole harness. Bottom line is I don't want to buy a new mower (this one works great when it goes) but I can't afford to have someone troubleshooting at $70 an hour. I could buy a new harness, but am worried about the modifications he made to the old one.

    Bookmark   August 11, 2014 at 10:36PM
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bill_kapaun

"there was a short causing something to kill the current before it starts"

The current going where?

Without knowing the Sears 917.xxxxxxx numbers of your tractor and the one from the "replacement parts", one doesn't have a clue if you used the correct parts.
There's over 200 different schematics for Sears Tractors.

    Bookmark   August 11, 2014 at 10:45PM
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