Repair Help? - Briggs & Stratton 135200 series L head engine

[dburkard]

Briggs & Stratton 135202-1127-e1 (ybsxs.2061.hc 274679)

It is a 5 hp single cylinder L head mounted on a Snapper tiller ... it has run flawlessly for 8 years (other than hard to restart when hot) ran it out of gas the last use ... filled it up and not it will not start ... it will fire once (one pop) and with that sometimes send visible flame out the carb every 1 in 10+ pulls, but nothing close to actually catching ...

We have removed air filter (same results), added gas directly in carb (same results), refilled the oil level to full, pulled spark plug cleaned it and brushed the contacts (same results multiple times), used starter fluid in the carb (same results multiple times) ... ideas, help?

 

[Willl]

Popping out the carb ?, just a thought, check the key-way in the flywheel.

 

[dburkard]

'popping out the carb' is the sound when it starts to fire ... ie it only one 'pop' or fire, nothing like getting close to catching ... I get some visible flame about once every 10+ pulls ...

 

[Travelover]

I'm wondering if the intake valve is hanging open a little. This would give you low compression and allow the firing through the carb that you are seeing.

 

[6thgpSF]

I'm with Willl, check the key on the fly-wheel russ

 

[Jim Thompson]

Most likely the flywheel key. Have you tried a different plug?

 

[dburkard]

Note that this is a magento engine:

I have the air filter off ... I have poured gas into the carb (as well as starter fluid) and after it blows most of it back out the carb for 5 or so pulls then I get flame/pops like it is trying to start for the next 3 to 5 pulls, but never more then a couple pops. I have removed the spark plug and cleaned it and poured gas (as well as starter fluid)direct into the chamber with the same results ...

First question -> is the flywheel key the part that is "in" the magneto sticking out towards the fly wheel? If so it is still there and there is a small gap of a millimeter or 2 between the pin and the flywheel ... If that is not the key, then where do I find it exactly? (I have the parts list with diagrams, and it shows the fly wheel key in the diagram as the magento, but does not show where it actually sits ...)

2nd question is that when I put gas in the carburetor or starting fluid I get flame / 'pops' like it wants to try to start after 5 or so pulls and then the pops stop after a couple of pulls ... it almost seems like i am not getting any inflow of gas into the carb/combustion chamber ...? Or perhaps have something causing a leak in the chamber ...? I have not tried to pour oil direct into the chamber ... to see it something is leaky and the oil might block it enough to have better results ... just not sure if it is leaky why it would be from one use to the next ... is it advisable to try to add oil to the chamber to 'test' for small leaks? If so then how much oil and any particular weight oil??

When I ran it out of gas perhaps gunk in the bottom of the tank clogged something along the way .... I have hesitated to take the carb off as there are a lot of connections etc and I did not want to be have a problem reattaching it as I do not have the repair manual for the engine to help make sure I get it all back together correctly ...

 

[TonyMcD]

The flywheel key is in the center of the flywheel. It fits in a slot in the crankshaft and a slot in the flywheel. You can't see it till you remove the nut and washer from the flywheel. Some engines you can see if the key is sheared or partially sheered, but you may need to remove the flywheel to tell.
It doesn't take much to shear the key, and can save from having more serious engine problems. ( like hitting a stump with a pushmower when the blade comes to an abrupt stop, the key shears keeping the weight of the flywheel from twisting the crankshaft, etc...)

Like said above, maybe a stuck valve, or possibly clogged exhaust?

 

[dburkard]

THe flywheel key is intact and I am getting good 'spark at the spark plug. Looks like it is the valve or something in the carb / chamber ... any advice of what specifically to do / check?

 

[Travelover]

Do you have a compression gauge? As I recall you need about 100 PSI to start easily.