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Briggs OHV Mower engines w/Plastic carburetor

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Briggs OHV Mower engines w/Plastic carburetor

Postby bgsengine » Sat Jul 28, 2018 1:40 pm

Second time I have seen this , nearly identical symptoms. Problem - Mower starts right up easily, runs approx 5 minutes and stalls out, restarts easily, seems to run fine except that stalling issue, May or or may not be accompanied by a lean surge or misfire. First teardown, find absolutely nothing wrong with carburetor or fuel system, clean fresh gas, everything clear. Trick is to do a "hot" teardown , when the carburetor is still warm and affected by engine heat..

The culprit - the venturi pictured here:
Image

When torn down and carb is still warm/hot , remove the main jet (as if to clean or replace) and tap the air cleaner side firmly on your workbench, voila, the result:
Image

non replaceable, non-serviceable venturi likes to fall out once it warms up, that loose fit allows air to bypass the venturi and you got a lean surge or a stall
How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)
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Re: Briggs OHV Mower engines w/Plastic carburetor

Postby KE4AVB » Sat Jul 28, 2018 2:30 pm

Yelp I have done replace a couple these carbs because of this. Definitely not fan of plastic carbs.
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Re: Briggs OHV Mower engines w/Plastic carburetor

Postby stienut13 » Sun Sep 09, 2018 6:41 am

The plastic jet cartridge holds the the Venturi in place. Take it all apart, remove cartridge, put Venturi in with the hole down and put the cartridge back in. That will hold it.
I like the idea, but the execution and functionality of the carb leaves a lot to be desired.
Went down that rabbit hole last week.
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Re: Briggs OHV Mower engines w/Plastic carburetor

Postby KE4AVB » Sun Sep 09, 2018 7:33 am

What Brian was referring is a loose fit once the carburetor is warm or hot. A slight plastic shrinkage problem which have seen on nylon gears mount on metal cores. The nylon shrinks and leads to broken gear rings. Same thing here accept there is nothing to cause it to break. It could always be lie the Poulan chainsaw gas caps that the plastic is swelling making it nearly impossible to get the gas off without pliers.

Anyway the only solution is to replace the carburetor as the OEM decided not to make this part available separately. It just like those Nikki jets that Briggs sells but not the teeny tiny o-rings where they are available if you know where to get them. But it funny that since I got them I have seen only one jet needing them. :lol: Just my luck. I still do a lot of Niki bowl gasket replacements which probably why I got 10 of them on the shelf that just came in.
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Re: Briggs OHV Mower engines w/Plastic carburetor

Postby bgsengine » Sun Sep 09, 2018 10:33 am

stienut13 wrote:The plastic jet cartridge holds the the Venturi in place. Take it all apart, remove cartridge, put Venturi in with the hole down and put the cartridge back in. That will hold it.
I like the idea, but the execution and functionality of the carb leaves a lot to be desired.
Went down that rabbit hole last week.


Actually that plastic venturi is not even supposed to come out at all,if it does, the carb is junk.
How poor are they who have not patience. What wound did ever heal, but by degrees? - Iago (Othello Act II, Scene 3)
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