JD D100 Will Not Start

PapaDrew88

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Hello,

I'm Working on this JD D100 riding mower, 17.5 HP B&S OHV for elderly neighbor. Neighbor was cutting his grass and then it cut off and will not start back. Engine turns over fine. Mower is 10 yrs old and has been serviced annually.
1) Great Spark
2) Getting plenty of fuel (removed hoses and fuel flow is good, new air filter, fuel filter)
3) Removed fuel bowl and everything looks brand new inside bowl, no varnish
4) Removed spark plug and piston is moving in and out
5) Gas spits out plug hole when choke is on trying to crank
6) Oil level is good (mower serviced in Sept)
7) Verified fuel shutoff solenoid is working correctly
8) Did a compression test with and compression is 100psi
9) Shaft is turning all the way to main drive pulley but have not pulled flywheel off to check key

What am I missing? I feel it is something internal. Thanks for any suggestions.
 

bertsmobile1

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GEt new pug and a can of carb cleaner .
Give the engine a short shot of carb cleaner down the plug hole, replace the plug & crank the engine
It should fire once or twice
If not then the timing key is broken or a valve is stuck fully open

If so do the same down the carb throat
Should start.
If it does hen continue to give it short shots of carb cleaner for a minute or so.
If you can then the mower definately has a fuel supply problem

Let us know what you find
 

PapaDrew88

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Hi, thanks for the response. I sprayed a bunch of starting fluid in the plug hole and tried a new plug and still didn't hit. Sprayed it down the carb throat and also sprayed it into the intake valve. Also I checked the valves and they are moving in and out as they should. Valve clearance is correct. Also removed the flywheel and key looks brand new.
Maybe it is an internal issue and the timing is off?
 

bertsmobile1

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Take the blower housing off and note where the magnet is with respect to the magneto coil when the piston is closest to the head.
It should be just past 1 leg of the magneto coil if the cam is in time with the crank .
Also have a close look at the valve stems / rockers .
The valves are the same length so should sit at the same height when the piston is in the firing position .
F you find debris under the blower cover that is obstructing the air flow then a valve guide could have shifted .

ANd when ou said a "bunch" of starter fluid. I hope you meant a very SHORT SHOT like about 1/2 second because you can flood an engine just as easy with stater fluid as you can with pouring fuel down the plug hole or holding the choke on .
 

PapaDrew88

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Thanks again, Ill take a look at these suggestions, yes it was several short bursts of starting fluid but I done it several times throughout the troubleshooting process.
 

bertsmobile1

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If the valves are not working but the pug is firing at te right time then you should have gotten some sort of fire with starting fluid down the plug hole
Through the carb if the inlet is not closing\Through the exhaust if the exhaust is not closing
A single muffled fire then backwards if neither valve is opening .
 

PapaDrew88

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Hi Mr. Bertsmobile1,

I finally had an opportunity to look at the next steps of the troubleshooting process per your tips. I am enclosing some pics my findings. When the piston is closest to the head, the valves appear to be sitting at the same height. The magnet I assume is in the correct position in relation to the magneto. Also when I pulled the valve cover off, the oil seems to have a strong fuel smell, but not sure if that is normal since it is in the valves. I also bought a compression gauge and I have a compression of 100psi. I was going to send you a video of the mower turning over and the spark I'm getting but I am unable to upload it. I look forward to hearing your response Sir, thank you!
 

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bertsmobile1

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Take the valve photo from the other side
You are looking for the position of the end of the valve but laying the square on the edge of the springs, it should be parallel to the gasket face if the valves are at the same height.
oil that smells like fuel is caused by the float valve not stopping the flow of fuel into the carb.
The float bowl has an air vent in it which because of EPA regualtions is now internal so you can not see the fuel leaking.
IT dibbles out of the carb then trickled down the manifold into the engine then past the rings and into the sump.
IT must be removed before you try to start the engine
and of course the carb needs to be fixed .
 

PapaDrew88

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Thanks, I will check it out and take pic as soon as possible. This really means a lot, you are a great teacher.
 

PapaDrew88

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Hi Mr. Bert,
Here is a pic of the valves from the other side as you suggested. They look to be the same height. I have also left a picture of the carb in full choke position and throttle position at low speed.
I took the carb apart and checked everything. Carb looks brand new. There is no sediment or varnish build up.
The float is working properly and sealing off. No flow when fully seated. I blew out the orfices with a small air pressure and reassembled.
 

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