After much trying, mower will not start

[Dan357]

Hello,
I have a John Deere JS28 7800824
Briggs 128M02 0423 F1

What I have tried

Removed tank, fresh fuel, checked line
Removed carb, cleaned, looked really clean but did it anyway.
New plug, gapped at 30 thousands
Checked for spark
Oil is clean and full
Checked flywheel key
Checked coil. 4.5 ohms




Sounds and feels strong, but will not start even with starting fluid.

I just don't know what to try next.

Any thoughts would be great.
Dan

 

[MowLife]

I would check compression if all the things you did check work properly.

 

[bertsmobile1]

put some fuel / starting fluid down the plug hole and try to start it.
Might take a dozen or so pulls
Engine goes bang at least once = ignition timing & spark is good
Flame out the carb = stuck inlet valve
Flame out the exhaust might = stuck exhaust valve.

Do the same with fuel down the carb
starts & runs the fuel out = fuel supply problem
Does not start = valve problem

 

[Dan357]

I would check compression if all the things you did check work properly.

Thank you for the suggestion, could you recommend a compression tester? I know harbor freight and amazon are some choices, but I'm not sure what to buy?

 

[Dan357]

put some fuel / starting fluid down the plug hole and try to start it.
Might take a dozen or so pulls
Engine goes bang at least once = ignition timing & spark is good
Flame out the carb = stuck inlet valve
Flame out the exhaust might = stuck exhaust valve.

Do the same with fuel down the carb
starts & runs the fuel out = fuel supply problem
Does not start = valve problem

Bert,
Thank you, I will try those steps.
Dan

 

[raider820]

Hello,
I have a John Deere JS28 7800824
Briggs 128M02 0423 F1

What I have tried

Removed tank, fresh fuel, checked line
Removed carb, cleaned, looked really clean but did it anyway.
New plug, gapped at 30 thousands
Checked for spark
Oil is clean and full
Checked flywheel key
Checked coil. 4.5 ohms




Sounds and feels strong, but will not start even with starting fluid.

I just don't know what to try next.

Any thoughts would be great.
Dan

Check your cable. If everything else checked out, sounds like the safety switch is not opening enough to allow the mower to start.

 

[SeniorCitizen]

Did you know that, with a helper to do the cranking, you can check compression, spark and spark timing without any tools? Your thumb, your eyes, ears and the spark plug threaded portion touching the cylinder head is all that's needed.

If an engine has enough compression to start it will be difficult to hold your thumb/finger on the spark plug hole and keep it there through a compression stroke. Now for spark and timing. Watch the spark plug for spark and if timing is about right you'll see the spark at the exact moment your thumb/finger is blown from the plug hole. Keep doing this for a few compression strokes and you'll have it mastered. Scientific? certainly not, does it work? You bet it works, and I've been using that method for a few decades now.

OH, at the moment we're just wanting to determine if the engine will run and not concerned bout all that other safety shutdown crap. So go ahead 1st. thing for this test and disconnect the magneto ground wire that's often located on the side of the engine.

 

[Dan357]

Thank you for all of the information, I will try working on it again on Saturday, and let the thread know what I find.
Dan

 

[Dan357]

Hello
I ordered a compression tester off of Amazon, the engine has zero comprehension.
I tried several times, nothing.

I checked the oil and it's very clean.

Could this be a valve issue?

Thanks
Dan

 

[Luffydog]

Take the plug out take a screw driver and put it in the plug hole and feel it the piston goes up and down by turning the engine over slowly by hand.