17.5 hp MTD Yard Machine turns but no start gahhh!

Boudreaux In Eunice La. said:

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 ~!~!

Click to expand...

Well Bo, more heads will prevail ! from what I found, he's got the OHV, like mine, good lil engines EXCEPT for the BACKFIRE upon shut-down, but I found if you bring it back to idle and let it run a few min. that will usually eliminate the loud "BANG" associated with this model Briggs, I sorta like it at times, ( scares the schitt outa anything or anybody near-by !! ) .. :laughing:..:laughing:

Hey all, sorry for taking awhile to get back here. I had my neighbor who lent me the spark plug tester come take a look at it with me. We sprayed some ether into the engine and it’s started running for a bit, then I turned it off and the starter kept spinning, we had to disconnect the batterry and the wires were getting all hot, it was freaky like a ghost machine! We determined after looking and seeing a bunch of blown wires and melted casings that it must have been on its last electrical legs and all the jumbling from being lifted and driven in the truck bed sent it over it’s edge. I definitely got played when I bought it and wish I’d taken a closer look, ******.

Anyway, it looks like I’m going to have to go wire by wire and replace them. What would really help me out with that is some sort of wiring diagram? I can go get that engine number if that’s needed, but would you all know where to find something to help me get an idea of things like that?

There is some phenomenal help here on this forum, thank you all!

All mowers are basically wires the same and they are not particularly difficult to wire up. if you can read wining diagrams.
The cranking circuit goes S on ignition switch through PTO switch through brake switch to solenoid trigger wire.
A simple daisy chain
The kill circuits are all in parallel
Seat + PTO
Seat + Brake.

Briggs did a book called "Alternator repower guide" and in it are the basic wiring diagrams of all mowers.
Toro put out the "Demystification Guide " which explains how all of the circuits work and has the wiring diagrams for Toros in it.

Most switches are double with 4 terminals in them.
Inside is a plunger with some brass on it so it either makes or breaks contact between the terminals FLAT TO FLAT.

Disconnect the wire going to the magneto before you start.
The cranking circuit is a power circuit, all others are ground circuits.
If you accidently hook up power to the magneto kill wire you will destroy it so leave it disconnected till you have finished then hook a test light between the kill wire & ground.
Go through ever operation ( spark plug removed so the engine does not start ) and make doubly sure the lamp never so much as blinks .
Then hook the test lamp to power and make sure it glows everywhere that the engine should stop.
When you are sure it is right, hook the coils back up.

I've taken these from the MTD shop manual for the 600 series mowers ( which I believe you have ) you will have to enlarge them, with your puters zoom feature to get a good view, hope this is helpful, keep us up-dated .......

View attachment 36484...View attachment 36485..

.View attachment 36486..... same as first one but changed rotation to save your n

RE-posting these because they are NOT showing up in my previous thread (THE SITE is the problem) something changes a viewable pic into non-viewable ..?????

these are the same pics, but I rotated one in the past posting to view it easier, (that's why 3 pics) it's rotated her though. ... Boo

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