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I have a Briggs & Stratton engine in my ~10 year old Craftsman riding mower (model 917.288561). Earlier this mowing season, I noticed the engine was progressively taking longer and longer to turn over, until one day I got no sounds or response from the engine at all when turning the key in the ignition. I finally got it to crank again by installing a new solenoid (I also replaced the battery and ignition switch on my way to isolating the solenoid as the problem). I was able to start the engine and mow a half dozen times, but the cranking at startup still ran very, very long.

Last weekend, I believe the new solenoid “died” - I heard a single click, but then turning the ignition (again) elicited no sounds or responses from the engine. I don’t know if it’s possible, but I wonder if I damaged the replacement solenoid with the excessive cranking. I had _another_ replacement solenoid lying around, so I installed it, and now I can again get to a cranking sound. But I feel like I’m not addressing the root cause here.

My next step is to purchase a sparkplug tester to see if (when turning the key) the ignition coils are sending spark to the sparkplugs or not (my engine has a pair of coils/wires/spark plugs), and maybe a feeler gauge to ensure the magnet is the right distance from the coil. I wonder if the ignition coils need adjusting or replacing. The spark plugs themselves are fairly new, I replace the plugs and all filters when I change the oil every spring.

My question is: does this (sparkplug tester and feeler gauge) seem like a reasonable next troubleshooting step? Am I missing anything?

I would start by making sure the choke is closing all the way. doesn't take much from complete closing to cause long crank issues.

Thank you for your reply. I’ve never replaced the carb on this riding mower...can the choke wear out over time? If it’s not closing completely, and I don’t see anything obviously wrong with the linkage from the choke lever to the choke on the carb, is it time to replace the carb?

You don''t say if you have a single throttle/choke control or separate controls. One the single control the cable has been known to slip over time and then not allow the choke to close all the way. I would apply the choke and then look into the carb opening to see if it is closed all the way.

The cable slips under the clamp
So you loosen the cable clamp, turn the choke on fully then close the choke with your finger and tighten the cable clamp again.

It is a single throttle/choke control, and you both were right! I loosened the clamp, held the choke closed with my finger, and re-tightened the clamp. Started right up on the next turn of the key, like it was brand new. I haven’t driven it yet, but I will this weekend. Thanks so much to you both!!!

Billylegend said:

I have a Briggs & Stratton engine in my ~10 year old Craftsman riding mower (model 917.288561). Earlier this mowing season, I noticed the engine was progressively taking longer and longer to turn over, until one day I got no sounds or response from the engine at all when turning the key in the ignition. I finally got it to crank again by installing a new solenoid (I also replaced the battery and ignition switch on my way to isolating the solenoid as the problem). I was able to start the engine and mow a half dozen times, but the cranking at startup still ran very, very long.

Last weekend, I believe the new solenoid “died” - I heard a single click, but then turning the ignition (again) elicited no sounds or responses from the engine. I don’t know if it’s possible, but I wonder if I damaged the replacement solenoid with the excessive cranking. I had _another_ replacement solenoid lying around, so I installed it, and now I can again get to a cranking sound. But I feel like I’m not addressing the root cause here.

My next step is to purchase a sparkplug tester to see if (when turning the key) the ignition coils are sending spark to the sparkplugs or not (my engine has a pair of coils/wires/spark plugs), and maybe a feeler gauge to ensure the magnet is the right distance from the coil. I wonder if the ignition coils need adjusting or replacing. The spark plugs themselves are fairly new, I replace the plugs and all filters when I change the oil every spring.

My question is: does this (sparkplug tester and feeler gauge) seem like a reasonable next troubleshooting step? Am I missing anything?

Click to expand...

Was having the exact same challenges - the only way I could get it to start was with starter fluid. Changed, fuel, filter, plugs, cleaned carb and replaced solenoid to no avail. Finally, removed solenoid, clipped off plunger, installed fuel shut off valve after carb and presto! Starts and runs like a champ, every time!

Unfortunately after a few months with no problems (maybe around a half dozen uses) I was in the middle of a job today and the mower just wouldn’t start again. LCD display shows me the battery is still working, but no sounds when the key is turned (new starter). Somehow I probably burnt another solenoid. Thanks to the fix suggested above (adjusting the throttle/choke cable), I wasn’t having long cranking times anymore, so I’m not really sure how it happened. I’ll get a replacement solenoid on Monday to try and swap it out, and update this post. Any suggestions are appreciated.

Before you start replacing parts willy nilly it is a good idea to work out what is wrong first
Otherwise you are just urinating up a wall .
So first of all
Can you rotate the engine by pressing down on the fly wheel screen and turning
If not then you need to look at the valve lash
Does the engine crank if you take the spark plug out ?
If you bridge the cables on the solenoid does the engine crank ?
If you bridge from the battery cable to the trigger wire on the solenoid does it crank ?

bertsmobile1 said:

Before you start replacing parts willy nilly it is a good idea to work out what is wrong first
Otherwise you are just urinating up a wall .
So first of all
Can you rotate the engine by pressing down on the fly wheel screen and turning
If not then you need to look at the valve lash
Does the engine crank if you take the spark plug out ?
If you bridge the cables on the solenoid does the engine crank ?
If you bridge from the battery cable to the trigger wire on the solenoid does it crank ?

Click to expand...

You are right, I need to be more systematic about it. Given the history of this problem with the two solenoids I’ve already replaced after swapping the battery, starter, etc, running all the multimeter tests - and facing the same symptom (key turn, LCD display but dead silence), I assumed it was the solenoid again. But you know what they say about assuming. I appreciate the list of things to check, and I will.

I have a couple questions please:
- is there a way to safely bridge the cables/posts on the solenoid? I’ve done it before with a screwdriver and there’s a pretty good spark
- bridging from the battery to the solenoid trigger wire - which wire is the trigger wire? I assume it’s not the hot wire coming from the battery or the wire leading back to the starter. It’s got to be one of the other two?
- do you want me to take both sparkplugs out? Alternate one and the other? this is a dumb question (sorry), but why/how would the engine crank without spark plugs?

Billylegend said:

You are right, I need to be more systematic about it. Given the history of this problem with the two solenoids I’ve already replaced after swapping the battery, starter, etc, running all the multimeter tests - and facing the same symptom (key turn, LCD display but dead silence), I assumed it was the solenoid again. But you know what they say about assuming. I appreciate the list of things to check, and I will.

I have a couple questions please:
- is there a way to safely bridge the cables/posts on the solenoid? I’ve done it before with a screwdriver and there’s a pretty good spark
- bridging from the battery to the solenoid trigger wire - which wire is the trigger wire? I assume it’s not the hot wire coming from the battery or the wire leading back to the starter. It’s got to be one of the other two?
- do you want me to take both sparkplugs out? Alternate one and the other? this is a dumb question (sorry), but why/how would the engine crank without spark plugs?

Click to expand...

Ok, so I can rotate the engine by pressing down on the flywheel screen and turning. So “check”.

I reattached the solenoid (I had detached it to get the part number) and accidentally touched the hot battery wire to the black solenoid post wire (trigger?) and the engine cranks. So inadvertent “check”.

I tried bridging the posts using the screwdriver and along with a nice spark the engine cranks. So “check”.

I tried turning the key in the starter, and miraculously it starts again. I’m scratching my head as to what’s going on here. One day, nothing (expect LCD display), today it starts normally.

your ground cable tight at both ends?

Crank = rotate
Fire = goes bang at least once
Sparks are fine, that is the prime function of the solenoid , to reduce the sparking from the heavy current draw
At the base of the solenoid will be 1 or 2 thin wires .
The dark colour will be a ground and the lighter one will be the power .
One or both could be switched
So check them for ground and jump from the battery cable to the other
If the solenoid trips and the engine cranks then the solenoid is fine
If neither wire is ground when all of the controls are in the starting position and neither are power then you have a cranking circuit problem

For safety reasons , always disconnect your black ground negative cable from your battery until you are ready to start actively testing your circuit. That will eliminate any accidental sparks .

Also a remote starter button works better than a screwdriver when trying to jump the solenoid.

Sorry for the late response, I only get to work on the lawnmower on weekends. First let me respond to the suggestions above (for which I am grateful, so thank you) and then I will share what my experience lately has been.

To @Scrubcadet10, thank you - but I’m a newbie and not sure which two ends of the ground cable you’re referring to. The end on my battery is tight and the ground spade connected to the solenoid is tight. I’m fairly sure the other ends of both cables is tight too but I’ll double check tomorrow.

To @bertsmobile1, thank you - I’m pretty sure the thin wires attached to the spades at the end of the solenoid are correct based on Sears videos and diagrams I’ve looked at. The thin white/power end is on the same side of the solenoid as the thicker red hot wire from the battery. The thin black/ground wire is on the same side as the thicker black wire with a red strip headed to the engine block. I’m sorry, I’m not sure what you meant when you said “jump from the battery cable to the other”, if you could please clarify I’d appreciate it.

@Rusty Knuckles, thank you.

Here’s what I’ve noticed lately with the mower. When it’s “cold” (been sitting), it cranks and fires right up like new. BUT, once I drive it around for a while and use it (I scoop up leaves with it lately), and turn the ignition key off, it will NOT crank or fire again when I turn the ignition key back on. As described above, I get power to the tiny LCD window but nothing else, no sounds, nothing. Like it’s dead. I’ve experienced this “cold start only” phenomenon at least 2-3 times now, consistently. Frustrated and needing to continue my massive leaf job today, I grabbed a screwdriver, turned the key and jumped the solenoid, and it cranked, fired, and started right up. I finished the job by just leaving the mower idling lightly while I emptied my leaf bag instead of turning off the ignition. As a test, once I parked it back in my shed for the day, I turned the ignition off, waited a beat, and tried turning the key again - and again, with the engine ”hot” nothing except the tiny LCD display. I bet if I try to start it tomorrow morning (cold) it might work.

One other thing I’ll mention is that I noticed that the screw holding down the solenoid to the mower frame was a tad loose today and I tightened that, but it didn’t make a difference.

Any clarifications to the questions above are appreciated, and any comments on my experience above are appreciated too. Thank you for your patience with me.

The solenoid is just a switch
It is electrically controlled and works by an electromagnet closing a pair of big contacts which are usually held open by a big spring .
This happens very quickly which avoids the creation of a massive spark as you got with your screwdriver across the top cables.

For the electromagnet to work it needs connection to both the + & - sides of the battery
On some there are 2 thin trigger wires at the base to make these connections
On others there is only a + trigger wire because it grounds via the mounting bolts / screws as the metal part of the body is not insulated from the magnet coil
This type are highly prone to corrosion making the - connection bad .
To test the single wire type you make a good ground connection to the metal part of the body then jump from the battery cable to the trigger wire .
Every time you make the connection it should give a loud klunk and if the connection to the starter is good and the starter itself is good, the engine should crank.

The single trigger wire does a full loop on most mowers as it starts from the power feed to the key switch, which is generally on the battery cable of the solenoid ( to save wire ) , then goes through fuse to the key switch then from there to the PO switch followed by the brake switch then back to the solenoid on the trigger terminal .

IF your solenoid is not activating then there are 3 switches to be tested plus the wires between them
So when you turn the key & nothing happens you need to check that you have battery voltage at the + trigger terminal .
THis needs to be done 20 or so times to verify it is working properly all the time .

The 2 trigger wire solenoids work exactly the same except the - trigger wire can also be switched .
You check that by testing for ground with the key off , the brake off & the PTO on
If you have ground in all those situations then it is just a ground wire and for the purpose of checking the + trigger feed you jump this terminal directly to the battery - to avoid any problems with the ground wire giving you wrong results
If the solenoid activates normally when the ground terminal is jumped then the ground wire is what is being naughty .