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Have asked this a few times and still can not find out why.
5hp Briggs will not start getting gas pull the plug and ground it next to the plug hole and it runs put plug back in and it will not run.
20hp briggs twin same thing just pulling one plug and ground next to the plug hole.

Many have said no way it will run like this but it does.

And of course someone said could be your valves

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Theoretically, an engine needs three factors present and in the correct proportion to start and run properly - the correct air/fuel ratio (fresh, quality fuel is a must), sufficient compression (arguably 90 P.S.I. or better) and sufficient spark at the correct time. How bout you make a video of the engine running with the spark plug grounded next to the hole, as you claim, so we can see what you are talking about? And yes, it's probably the "valves".

Carscw said:

Have asked this a few times and still can not find out why.
5hp Briggs will not start getting gas pull the plug and ground it next to the plug hole and it runs put plug back in and it will not run.
20hp briggs twin same thing just pulling one plug and ground next to the plug hole.

Many have said no way it will run like this but it does.

And of course someone said could be your valves

Sent from my iPhone using LMF

Click to expand...

Funny you should mention this, my Briggs will not start and run unless I unplug the spark plug wire and keep it about 1/4 inch away.

Briggs engine running with no Spark Plug - YouTube

Gas engine running with no carb or spark plug - YouTube

Can you tell me how it works, posted the videos awhile back and no one could solve the problem. This is a old mechanic secret.

Rivets said:

Can you tell me how it works, posted the videos awhile back and no one could solve the problem. This is a old mechanic secret.

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no, i don't know - might involve some gasoline in the crankcase and somehow having the spark jump from the piston to the head - maybe some kinda insulating material on the head bolts so the head doesnt short high voltage to the cyl? secret wiring from the coil to the head?

maybe an internet search would find the secret

I'll look around too when i get the chance

RFouce said:

Funny you should mention this, my Briggs will not start and run unless I unplug the spark plug wire and keep it about 1/4 inch away.

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I had an engine do that once. Turns out there was a short in the plug wire where it came out from under the flywheel shroud. When I moved the wire to unplug it, I removed the short.

RFouce said:

Funny you should mention this, my Briggs will not start and run unless I unplug the spark plug wire and keep it about 1/4 inch away.

Click to expand...

Have you replaced your spark plug?
It's possible your plug Is shorted inside and this works because it makes the spark hot enough to jump the short

Very interesting, as i am on duty today i will replace the wire tomorrow and see if that helps, thanks all who replied.

RFouce said:

Very interesting, as i am on duty today i will replace the wire tomorrow and see if that helps, thanks all who replied.

Click to expand...

So did you try a new plug? That is the easiest thing to try first.
If you don't try that first but start replacing other more expensive parts you may be wasting your time!