17.5 hp MTD Yard Machine turns but no start gahhh!

Smallenginesidiot

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Hey all, I’m new here and am having a lot of trouble with a mower (17.5hp 42 in deck yard machine MTD) I just picked up. Long story short, it worked when I bought it (when he jumped the battery), we put it in my truck with a forklift, I unloaded it at home, replaced the battery with the standard mower battery found by the mowers in Home Depot, it didn’t start, tried jumping the battery, didn’t start. When I turn the key the engine turns maybe once per second, consistently, failing. Mower in neutral, blades disengaged, seat safety wires disconnected and he showed me the mower starts like that in front of my own eyes. I haven’t messed with the older gas or oil to drain and replace or anything.

This has been my first run in with trying to diagnose an engine, and it’s been a pretty ignorant and in the dark process haha. Things I have done: I saw the wiring from the battery to the engine etc. was pretty old and jacked up, so thinking that was the problem I ran current straight to the starter (I believe) with a battery jumper and turned it on- same thing happened as when I turn the key. Next I talk to my neighbor, get a spark plug tester from him. It lights up in sync with every failed turn of the engine, so the spark plug is good, correct? I poured a tiny bit of gas down the air intake because I read if it starts temporarily it means “yada yada” is the problem, it didn’t start which is why I’ve forgotten what that’d indicate (spark plug?).

I have a multimeter and most basic tools, I’d really like to fix this problem myself I just need a good talk down and pointing in the right directions. I can upload pictures as well if that would be helpful!

I should mention, it’s completely missing an air filter, I obiviously intend on replacing before I go out running the mower, but i didn’t think it’d be preventing it from starting, right?

Sorry for any ignorance and million thanks to anyone who might have a moment to share some advice. Appreciate it

Fin
 

Darryl G

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I would start with draining and replacing the gas. If it's been running without an air filter that's not good at all. May as well pour sand into the engine.
 

Boobala

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You said you replaced the BATTERY, ... did you install the NEGATIVE terminal to a cable (usually BLACK) that goes to the frame of the machine ??
The POSITIVE (usually RED) cable should go to one of the LARGER terminals on the starter solenoid.

Now lets get your machines model numbers, should be a sticker under the seat or on back of tractor, your engines info should be on the engine itself.
see example: GET INFO.JPG..... post the information so we can find the manuals to help you.
 

Smallenginesidiot

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You said you replaced the BATTERY, ... did you install the NEGATIVE terminal to a cable (usually BLACK) that goes to the frame of the machine ??
The POSITIVE (usually RED) cable should go to one of the LARGER terminals on the starter solenoid.

Now lets get your machines model numbers, should be a sticker under the seat or on back of tractor, your engines info should be on the engine itself.
see example: View attachment 36414..... post the information so we can find the manuals to help you.

Yes, thick red wire to the positive terminal and thick black wire to the negative. I’ve swapped batteries before, but I do think cleaning the terminals might help (but doesn’t seem like the whole problem). Here is that info: 1AB1EA8F-790E-4908-A48A-63262053F258.jpg

I would start with draining and replacing the gas. If it's been running without an air filter that's not good at all. May as well pour sand into the engine.

Yeah... I wasn’t even aware of what one was until I went looking. Not ideal but not much I can do about the past abuse other than not buy something like this again in the future. I’ll try changing the gas because that needs to happen regardless
 

Boobala

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GREAT for the mowers model number... (you need to save that pic and keep it safe, you will need it EVERYTIME you order parts for the MOWER !! )

Now ...... Annnnd the mystery engine numbers arrrrre ???? .........

OK I just checked your mower manual, and it looks like you have the Briggs & Stratton, eng. ( 17.5 HP )
I"m going to start a new post (in this thread to make life easier..
 
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Boobala

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Make sure the battery is fully charged (12+ volts)
Be sure the engine oil is full...( not OVER-filled )
Remove the spark-plug... now using jumper cables... connect the Neg. battery cable to good frame ground and take the cable from the Pos. battery terminal and touch the cable post on the starter, the engine should spin fairly fast, ( no sense in trying to trying to start if the engine has other issues.

If that much is good, replace the spark-plug, BE SURE ALL the battery cables ends ARE CLEAN AND tight! especially the NEG. (ground) cable ..... check the solenoid wires, and make sure the solenoid (if mounted to the frame ) is touching BARE metal ( remove and clean if necessary, now try to start the mower as a "normal procedure with the key, " does it spin normally, or does it rotate a bit and then seem to "hang at a certain point" .....if it "hangs" then try adjusting the valves (see enclosed link for your Manual, see Section 1,..Page 21 ).. after adjusting valves, see if engine rotates easier now ( normal start with key procedure ) sitting in operators seat,.. blades disengaged .. push clutch pedal (if equipped)

after we get this far (if engine rotates normally) push throttle wide open ( but NOT on choke if single lever !! ) put a SMALL amount of gas in the carb throat and try to start .... POST your results !

https://docs.google.com/file/d/0B6NaqjIxWV1ybEN0LWo3azl6OUU/edit

Still need the ENGINE numbers !! see top of valve cover or engine shroud on engine
 

BlazNT

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Lifting a mower with a Forklift can break things. Look for your safety switches that could be damaged or dislodged from lifting with a Forklift.
 

Boobala

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Lifting a mower with a Forklift can break things. Look for your safety switches that could be damaged or dislodged from lifting with a Forklift.

Good thinking on that point Chuck !
 

Tinkerer200

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Lifting a mower with a Forklift can break things. Look for your safety switches that could be damaged or dislodged from lifting with a Forklift.

My first thought too BUT as I understand it the engine is spinning good and has spark. Never the less first thing I would do is disconnect the Kill Wire from the terminal on the throttle box OR Kill Wire may come out the cooling shroud on the opposite side and simply unplug. Then try starting. Be aware that you will have to have an alternate way to shut the engine Off IF it does start. Ground Kill Wire terminal with jumper, shut off gas, pull plug wire for instance.

Walt Conner
 
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My first thought too BUT as I understand it the engine is spinning good and has spark. Never the less first thing I would do is disconnect the Kill Wire from the terminal on the throttle box OR Kill Wire may come out the cooling shroud on the opposite side and simply unplug. Then try starting. Be aware that you will have to have an alternate way to shut the engine Off IF it does start. Ground Kill Wire terminal with jumper, shut off gas, pull plug wire for instance.

Walt Conner

No I don't think the engine is spinning good... He mentioned that the engine turned over once per second and he did have a spark.....

I was gonna reply to take the spark plug out and then see if the engine turned over like it should, but Boo beat me to it..

I also think he needs a valve adjustment.... If it's a OHV engine, which I think it is......

Thaaaaanks once again for that reply Tink from a couple weeks ago ~!~!
 
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