Briggs engine

[dogdayz]

I have an OLD Roper yard tractor with a snowblower attachment that I use in the winter. It's probably 30+ years old but still works. The problem is it only runs with the choke almost fully closed (summer or winter). Even when it warms up the engine dies if I open the choke. I have tried tweaking the carb and it doesn't help. This summer I bought a whole new carb but it still needs to be choked to run.

Any ideas?

(There is good fuel flow, the air filter and fuel filter are clean)
The engine is a 16hp Briggs twin cyl.

[Terryl]

Does it have a foam type air filter??

[dogdayz]

It has a pleated filter that is covered with a foam pre-filter. They are both clean but even with the filters removed it still has to be choked to keep running.

[Terryl]

Sounds like it's getting too much air, the air/fuel mix is not right, it might be getting too much air and the engine is starving for fuel. (your not doing this with the air filter off are you?)

To test this go get some carb cleaner and spray it directly into the carb (small squirts only) when you open the choke, (after you get it started) if it runs then you may need to adjust the needle valve(s) on the new carb.

Carefully screw the needle valve in all the way till it stops (gently) then back it out 1-1/2 turns to start. With the air filters on.

And one last question...Did you torque the carb mounting bolts? if not then you may have an air leak around the carb gasket, usually 12 to 20 foot pounds, you can look this up on the OEM site for that engine.

[Terryl]

One other possible problem is a bad fuel pump or leaky fuel pump to valve cover gasket, the fuel pump runs off a vacuum supplied through one of the valve covers, if this gasket has a bad seal it wont supply fuel to the carb as needed.

I had this problem with my yard tractor, has a 22 HP brigs on it, a little bit of non-hardening form-a-gasket fixed it right up.

[dogdayz]

I guess I'll try playing around with the needle valve again.

[Terryl]

Do this with the air filters on, (engine off) and again start with it all the way in then back it out 1-1/2 turns, then try and start it, adjustments are done in small increments, try adjusting it out slowly, if that does not work then go the other way..

Another question...Did you get an OEM carb or a clone?

[The Noof]

My guess is the original carb had dirt in the main metering system, and your replacement carb is not jetted correctly for your application.Does it have adjustable low & high speed mixture adjustments, or only low speed?If it has only 1 mixture screw, that's for low speed only.

[runamok]

If the engine will run but not off choke then main fuel jet is blocked.Just needs a good cleaning.

[Terryl]

It's a new carb as he mentioned.

And if he didn't get an OEM carb then the new carb has a jetting problem, I would pull the jets out of the old carb and clean them, but be carfull as to what you clean then with, a correct diameter carb jet cleaning tool should be used, a paper clip or that may fit is not a good idea.

I find that some cases like this are due to spiders getting into the small spaces in the carb and trying to build a nest.

Also I always try to buy OEM carbs for my small engines, (if I can find them) the clone stuff does not always work right, and it that case swapping out the OEM jets may fix a problem with a clone carb.

[dogdayz]

It's a new carb so shouldn't need cleaning.

It's a B&S clone carb.

Can't see any mixture adjustments, but there is a big hex screw on the side, maybe a mixture adjustment under that. I'll have to take a look.

(I junked the old carb)

[runamok]

I was referring to old carburetor

[dogdayz]

hxxps://www.amazon.ca/Carburetor-693480-Replaces-Briggs-Stratton/dp/B07TQ5W9YG/ref=cm_cr_arp_d_pl_foot_top?ie=UTF8

[The Noof]

hxxps://www.amazon.ca/Carburetor-693480-Replaces-Briggs-Stratton/dp/B07TQ5W9YG/ref=cm_cr_arp_d_pl_foot_top?ie=UTF8

There's probably a mixture adjustment under the hex nut.Turn it counter clockwise to richen the mixture

[dogdayz]

There's probably a mixture adjustment under the hex nut.Turn it counter clockwise to richen the mixture

I'll try to check it tomorrow. Thanks.