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Discussion Starter · #1 ·
Hi guys
I have a B&S Quantum XLS50 Push mower with Cord Pull Start.
Engine number 12F802-1783-B1
I push the primer 3 times and it takes about 20 vigarous pulls to start.
I've checked primer bulb, inside the carb,air filter is clean, spark plug OK.
The Spark Plug Connector was a little rusty so i've scraped that with a screw driver.
The Gasket between the Air Filter & Carb was a little torn, I've ordered a new one. Could this be my problem ?
Should this model have a Gasket between the Carb & Engine ? There isn't one fitted, it has a sealing O ring but I can across this Carburetor Gasket 272199S Order now for same day shipping. 365 day return policy. RepairClinic.com
Should one of those be fitted between the Carb & Engine ?
Thanks For Any Advice :cool
 

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Yes, if the gasket is torn your primer will not work properly. When you replace the gasket make sure you take all the residue from the old one off. Plus, it does appear that there is a gasket between the carb and the engine block.

In the meantime, you may need to push the primer a few more times until you can hear/feel fuel being pushed into the carb throat.
 

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I've found on mine depending on how long it has been since the engine was run and the outside air temp 5 pushes on the primer works better at times. If it does not fire after a 2-3 pulls then give it another 1-2 pushes.

Any gasket leaks will lean out the air fuel mixture which is the opposite what you want for especially a cold engine. Replacing that being torn should make a difference.
 

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...Should this model have a Gasket between the Carb & Engine ? There isn't one fitted, it has a sealing O ring but I can across this Carburetor Gasket 272199S Order now for same day shipping. 365 day return policy. RepairClinic.com
Should one of those be fitted between the Carb & Engine ?
Thanks For Any Advice :cool
I made my first post on my iPod and did not pull up the diagram. Looking at the pictures on this site it looks like your engine originally only came with the O-ring for the carb to engine connection. So if the O-ring still looks fine I don't think anything would be gained by adding the flat gasket as well. But you do need to replace the air filter to carb gasket if it is damaged as that would let dirt bypass the filter and also could make the engine run a little leaner as it might slightly increase the amount of air coming into the carb.

Parts and Diagrams for Briggs and Stratton 12F802-1783-B1
 

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Discussion Starter · #5 ·
Thanks for the excellent replies guys ! :)
As I said, I've ordered a new gasket for beyween the Air Filter & Carb.
I've also ordered a gasket for between the Carb & Engine.
Would fitting this extra Gasket cause any problems ? The O ring does look OK

Thanks Again :)
 

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Discussion Starter · #7 ·
I've just fitted a new Air Filter to Carb Gasket but still got the same starting problem.
I've removed the Air Filter, looked through the Carb hole & pressed the Primer, I'm not seeing any fuel coming out of the Brass jet in the Carb.
The Primer Bulb looks fine, it has a manufactured hole in the centre of the bulb, which I could never work out why ?
Would i be better with a new Primer Bulb, one without this manufactured hole in ?
Thanks Again ;)
 

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....The Primer Bulb looks fine, it has a manufactured hole in the centre of the bulb, which I could never work out why ?
Would i be better with a new Primer Bulb, one without this manufactured hole in ?....
I think the internal passage design of the carb dictates whether the primer needs the hole in the center. I've always suspected that the ones with the hole prime when pushing (and your finger covers the hole) and the ones without the hole prime on the return stroke as the bulb expands back out.
 
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