Briggs 13hp wont start

Hey,

I got a lawn tractor for free that have been sitting outside for a few years. The electric start gear was worn so i replaced that. Drained all the old fuel and cleaned the carb. Ive checked the sparkplug and it got spark and is wet of fuel. But i havent replaced it. I will do that tommorrow. But i still dont think its the sparkplug fault because on the first try it acctualy started for a few seconds. I would really be thankful if someone could help me!

Thanks!

Sorry for my bad english. English ist my first language.

The carb may still need help. If the plug is wet, it could be flooding, or the spark may be questionable. Something to try-

Remove the spark plug, Shut off the fuel, and crank the engine for about 15 seconds to blow excess fuel out of the cylinder. Reinstall the plug, turn the fuel on, and re-attempt to start. Avoid using the choke. Post results and we'll go from there.

Your English is just fine, better than some people born speaking it! Welcome to ATLTF!

Will try that tomorrow with the new sparkplug and post results.
Thanks!

Also might want to make sure you have compression.. is air blowing out your intake when cranking, is it super easy to turn by hand?

So i bought a new sparkplug today and i cleaned the carb. I also did as you doc told med to do. But the engine still dosent want to start. I only got some backfire thru the airfilter. I also tried removing the sparkplug and sparying a littlebit of quickstart gas and test to start it but it didnt help. So it seams like it's not sparking when it's inside the engine.. But i ruined the drive clutch so i need to order a new one before i can do anything.
And i also maked sure it have compression.

Thanks

Valve lash or cam timing is off

How do i fix that? I dont have so much experince with mower engines.

Check for spark. Remove the spark plug, and connect the wire to it. Wearing a glove, hold the threaded part of the spark plug tight against a bare metal part of the engine- like a head bolt or part of the aluminum block or head casting- and crank the engine as if to start it. Spark should be bright blue, and consistently firing on each revolution of the engine.

Report results and we'll continue on.

Yes it has spark that was the first thing i checked. Checked today again with the new sparkplug and it is still got a blue nice spark.

Thanks

Okay- so when you put fuel (or starting fluid directly into the spark plug hole and put the plug back in, you get no fire at all, save for backfiring?

If I have that right, You're down to compression and timing. You save you've got compression. How did you test it, and how many PSI was it?

Timing- the best spark in the world won't fire your engine if it comes at the wrong time. Here's what I want you to check: There is a rectangular but of alumimum called the "timing key" that indexes the flywheel to the crankshaft. There are grooves cut in both of them, that this key rests in. This key, in it's slots, sets the ignition timing, as it dictates when the magnet on the flywheel passes the coil.

To check the key, you have to remove the big nut that holds the flwheel to the crankshaft. Generally, you can tell without actually removing the flywheel. If the key is intact, good. If the flywheel has rotated on the shaft, the key will have been sheared in two. So, what you're looking for is a square bit of aluminum between notches in both the crankshaft and the bore of the flywheel. If the key is in 1 piece, the notches (keyways) will be lined up with each other. If the key has sheared, the notches will appear out of alignment, and the ignition timing will be off.

Also to add to what doc said. Valve lash can be a factor, and so can be cam timing.. it can skip a few teeth on the came and cause problems. +what doc said.

Exactly nothing happends exept backfiring and it comes fuel up in the airbox. I pretty sure the compression is good cause it was pretty hard to move the flywheel with my hands and i compared it to my other working mower. When i removed the flywheel to change the ring starter gear it looked like new, not worn at all.

So only thing that could fail now is the timing?
I really appricate the help

MaCKiiN97 wrote:

When i removed the flywheel

Ah-HA!!!! Dingdingdingdingding!!! We have a winner!!!!!

I'm going to jam $50 into my USB port that says, "when you bolted the flywheel on, you did NOT manage to torque it to the specified 150ft-lbs, and the timing key sheared".

This is DEAD common. Folks tighten the nut to "tight enough", and *poof*... Key sheared.

Check it, so I can get my $50 back. LOL

I dont tighten mine to spec.. Just tight as hell.. lol torque to spec.. I have my evil methods but they arent for others lol

TroyBilt Pony wrote:

I dont tighten mine to spec.. Just tight as hell.. lol torque to spec.. I have my evil methods but they arent for others lol

So... YOU'RE the guy I curse out profusely when I get something used, and set to work on it! LOL

Doc Sprocket wrote:

TroyBilt Pony wrote:

I dont tighten mine to spec.. Just tight as hell.. lol torque to spec.. I have my evil methods but they arent for others lol

So... YOU'RE the guy I curse out profusely when I get something used, and set to work on it! LOL

Yep. On these small engines. I dont worry much as a i got spares for everything but a crank flywheel and block lol.

lol hope it was so easy, going to check when i get home from school :)I used one of those things you plug to the compressor to tighten the nut, but atleast i dont think it's to lose. I have always used them on my dirtbikes and it have worked just fine.
One of those http://images.staticjw.com/ver/6616/mutterknackare.jpg

Thanks! Will post results when i get back home!

In English, we call that an "impact gun".

You'll have to let us know what you find. It's the most reasonable explanation I can think of...

Removed the flywheel today and the key was broke and the flywheel have rotated half a cirkel. Im gonna order some flywheel keys and a new drive clutch for the starter.

Thanks a lot! Will post results when i get the parts

I have GOT to start betting with real money... 

Yeah lol thanks again

Kidding aside, you're welcome.

I don't know how people break them. Ive pushed my engine to its limits and never had a prob.

I told you how they break them. By not sufficiently torquing the flywheel nut down.

The other time it happens, is when the engine comes to a very abrupt stop. It is for this very reason that the keys are aluminum, not steel. It is an engineered weak link, and protects the crankshaft. To draw an example- picture a push mower. You're happily cutting away at full bore, when you accidentally hit that city water shutoff valve that sits a little higher than it should. The blade goes from 3600 RPM to 0, faster than you can swear at it. That flywheel has a hell of a lot of inertia behind it, and desperately wants to keep spinning. So the key shears and prevents the flywheel from twisting the crankshaft in two.

If I had a nickel for every shorn timing key I have had to replace due to either of the two above reasons, I'd have really heavy pockets. Work on enough of them, and eventually you goof too.

Incidentally, I have found probably 50% of the time, it's on a Briggs, with the ball-type recoil clutch. Most people do not have the special tool required and therefore cannot torque it to spec, or even decently tight.

I'm not immune, either. A couple years ago, I was working on an 8hp Briggs-powered snowblower with an intermittent spark problem. With the points under the flywheel, I had to pull it off several times. Somewhat frustrated and hurrying, I had whipped it back together for probably the fourth time, to test it again. You guessed it- didn't snug that dang ball clutch down hard enough. RIP!

I will use the torque wrench next time I was thinking if i should torque it down but i decided to use the impact gun because i have never had a problem with that.