Briggs won't start

[Snapper987]

I have a a Snapper mower with a 675 series L head Briggs. Recently the mower has been very hard to start sometimes taking 40 plus pulls. When trying to start after emptying the bag it felt like there was little compression. I would get put put put then a short pop. The mower will start ok on a few pulls when cold. It originally had ready start but was converted to primer carb 2yrs ago. Could this be a bad exhaust valve? If so would it be worth fixing. Machine is 8 yrs old.

Briggs and Stratton 675 quantum
126T05-0678-B3
Serial 08032756

 

[bertsmobile1]

A head gasket is about $ 5 after that it is all time.
So that makes it a no brainer.
L head parts are very cheap

 

[Rivets]

If I have seen it once, I've seen it a hundred times. Cause, float seat has swelled causing the needle to shut off the fuel entering the float bowl to shut off prematurely, which will mean there is not an adequate amount of fuel in the bowl for starting. My solution is to rebuild the carb and replace the float needle and seat. I set the float level on the rich side. A good service tech knows how to do this, and now all the members who say you can't adjust a Briggs float can now start hating my reply as has been done in the past. FYI, part number needed is 398188.

 

[Snapper987]

A quick update. I managed to get the machine started to mulch the leaves in back yard. Still have hot starting difficulty. Upon further inspection I noticed the mower will backfire thru carb and intake when trying to catch. I did several days ago remember hitting a log and the mower stopped dead. It restarted afterwards. Is it possible that the flywheel key sheared enough to throw the timing off enough to prevent a hot start.

 

[bertsmobile1]

A quick update. I managed to get the machine started to mulch the leaves in back yard. Still have hot starting difficulty. Upon further inspection I noticed the mower will backfire thru carb and intake when trying to catch. I did several days ago remember hitting a log and the mower stopped dead. It restarted afterwards. Is it possible that the flywheel key sheared enough to throw the timing off enough to prevent a hot start.

YES.
Depending upon the model , decompression can be via the exhaust or the inlet.
Most late models are via the inlet ( EPA strikes again ) so on those you can & do get little backfires through the carb when hot starting.
So some spitting back or backifiring through the carb is not proof positive that the key is off.
If the inlet valve lash has decreased ( rare ) you will get a lot of spitting back at low speeds.