6.75 briggs trys to start dies

Hello, I just joined this morning and this will be a long post, sorry for that. The #'s off of the engine are 126T05-3216-81-10040756. This is my daughters Lawn Boy with this briggs engine. They asked me to look at it with the problem of not staying running. I brought it home and cleaned the carb, same problem. Ordered a new carb, exact same problem. Took the flywheel of and cleaned magnets, installed a new briggs flywheel key. Same problem. Ordered a new ignition, installed it and a new plug, same problem. Installed a new head gasket, same problem. I then lapped the valves, thought one might possibly might be leaking, put it all back together. Exactly the same. It fires when you pull the rope but won't stay running. Open the choke (held open with a screwdriver) it will start but dies after several seconds and never picks up like it is going to run. I read threw 30 pages of posts but didn't see this problem. I don't know what else to try, I'm looking for advice. Thank you I went out and bought her a new mower this morning but I would like to resolve this so I can sell this mower. I drained the fuel and added new, still the same.

Well Bill I don't blame you for wanting to fix and sell... Get some of that money you threw at it back..........

Make sure the 2 bolts that hold the carb plate, not the carb itself , but the plate that the carb bolts to are tight.

Next take the air shroud off and check the intake tube bolts....... Make sure they are tight......

Did you check for valve lash/ clearance when you lapped them ??

I wish I had the mower in front of me ..........

Let us know Mon Ami ~!~!

The parts that you bought new, are they OEM Briggs or fleabay cheapies ??

If you read through the 30 pages then you should have seen the following because it gets posted 5 times a day.

Arm yourself with an in line spark tester and a can of carb cleaner.
Hook up the spark tester then remove the plug.
Spray a VERY SMALL amount of carb cleaner in the plug hole.
Pull the starter.
THe tester should flash and the engine should fire a few times.
If it does the spark timing is good.
do the same but spray the carb cleaner down the carb throat.
If it fires then the valve timing is good and the valves should be sealing.
DO the same again but this time shoot some very short shots of cleaner down the carb throat
If you can keep the engine running for 30 seconds or longer by doing this ( it will be rough ) then the problem is no fuel getting into the engine.
All the time keep your 3rd eye on the spark tester which should always flash while the engine is revolving.

That engine is going on 9 years old........ The fuel line is probably bad on the inside of it... That is common.......

Or your tank nipple is clogged up with all the old junk that E gas causes......... 3 small bolts and 1 bigger one on the side of the engine holding it on ..........

A 3 minute job to take it off to check it and give a good cleaning..............

I just had one of these auto-choke models. The problem was the thermostat/air vane system. Clean the Tstat pivot point, then spray lube. Make sure the metal Tstat arm is located between the 2 sets of marks on the black plastic air vane. Check the air vane spring, too - may be stretched out. I tested the tstat with a hairdryer to simulate muffler getting hot and watch the arm move and decrease choke.

Thank you for the replies, I will get it checked out and post back. Probably won't get to it today but I will let you know what I find.

dougand3 said:

I just had one of these auto-choke models. The problem was the thermostat/air vane system. Clean the Tstat pivot point, then spray lube. Make sure the metal Tstat arm is located between the 2 sets of marks on the black plastic air vane. Check the air vane spring, too - may be stretched out. I tested the tstat with a hairdryer to simulate muffler getting hot and watch the arm move and decrease choke.

Click to expand...

Doug,,,,, What do you mean by T Stat arm being between 2 marks ???? The L head models for the EZ start auto chokes the T Stat arm stays toward the front of the engine...... It controls the air vane arm when the engine cools down..

Let me know Mon Ami ~!~! Plus Tard ............

Boudreaux, the one I had....the air vane hook has 2 sets of marks to keep the tstat arm centered. Front to Back and Left to Right. I had to bend tstat arm a little (triangle became a little smaller) to be centered.

I checked the choke thermostat with a heat gun and it moved forward, it didn't seem to move very quickly but it did move all the way to the front. I checked the intake manifold and the bolts did tighten some. Still does the same thing however. Waiting for the spark tester to arrive to check that out. The aftermarket coil I had installed was somewhat different in shape and wouldn't let the choke vane move properly. I put the original back on, it does fire but won't keep running.