5hp Briggs Will Only Run On Full Choke

[DaveDSR]

My 5hp Briggs and Stratton Horizontal, diaphragm carburetor, mechanical governor, will only run on full choke. It's been out of service for 20 years, and I'm trying to revive it. I couldn't get it to run at all with the original carb even after a thorough cleaning. I just installed a new, in the box, Briggs and Stratton carburetor, part number 498298 (original carb is 492611). The gas is fresh, the oil is fresh and the gas tank was cleaned. The engine started on the first pull with the new carb, but will only run on full choke. As soon as the choke shutter breaks contact with the casting wall the engine stumbles and dies. The engine is model number 132232, type 2238-01, code 88042127. I would appreciate any help toward a solution.
Thanks,
Dave

 

[Fish]

On those models, in the top of the fuel tank, is the carb "bowl". And those over time can get rusted out, and develop
holes, even small ones, and not hold gas, or may hold gas for only a short while, and let the thing only run on choke, as the fuel leaking out leaks too fast to let it run on anything but choke.

I have repaired tanks in the past by removing all of the rust, and patching the cup with JB Weld, as a decent redneck repair.
Not sure about long term results.

 

[DaveDSR]

On those models, in the top of the fuel tank, is the carb "bowl". And those over time can get rusted out, and develop
holes, even small ones, and not hold gas, or may hold gas for only a short while, and let the thing only run on choke, as the fuel leaking out leaks too fast to let it run on anything but choke.

I have repaired tanks in the past by removing all of the rust, and patching the cup with JB Weld, as a decent redneck repair.
Not sure about long term results.

Thanks for the reply.
I'm pretty confident that the "carb bowel" is okay. When I took the old carb off the "bowl" was full to the overflow.

This engine is on a small portable generator. 20 years ago it replaced the original engine, and was used to run a circular saw on a job site for 1 day only before being stored under a bench in a wood shop. Except for the fact that it doesn't run properly, it is in like new condition.

Any other ideas on what might be wrong. I'm stumped.

Thanks again,
Dave

 

[bertsmobile1]

Start with some fuel down the plug hole.
If the engine is fine you should get 1 to 3 fires
Then try some down the carb throat.
If the valves are working it should run 15 sec to a minute the run out of fuel
If both of these work fine then your carb is just not as clean as you think it is.

Did you remove the gauze that covers the main jet housing then check you can see, blow or squirt through the main jet ?

 

[Rivets]

You have a pulsa jet carb, which means the first thing I would check is, did you adjust the mixture screw on the carb to 1 1/4 turns out for initial adjustment? Once it is running you then adjust for best operation. Second, did you replace the carb to tank gasket? If you didn’t it may not be sealing, allowing air in, not allow the pump to operate properly. Third, I know you said you installed a new in the box carb, but it may have been sitting around for some time and the pump diaphragm may need to be replaced.

 

[DaveDSR]

Start with some fuel down the plug hole.
If the engine is fine you should get 1 to 3 fires
Then try some down the carb throat.
If the valves are working it should run 15 sec to a minute the run out of fuel
If both of these work fine then your carb is just not as clean as you think it is.

Did you remove the gauze that covers the main jet housing then check you can see, blow or squirt through the main jet ?

Appreciate the reply!
You got me thinking. I reread my original post on this thread, and realized that I made a mistake. The engine wouldn't run at all BEFORE I cleaned the original carb. After I did my "thorough cleaning" it ran with the choke wide open, but it surged, or searched, or hunted badly. If I applied a little choke it smoothed out a little. More than a little choke killed it. If I held the throttle linkage steady when it was running with the choke wide open it ran fine, sounded good. Adjusting the idle mixture screw from shut to ready to fall out made no difference. I guess my cleaning wasn't as thorough as I thought it was.

Both the original carb and the new carb have a welch plug sealing the end of the main jet housing. The only place there could be gauze would be covering the screen on the end of the pick up tube on the new carb. I don't remember seeing anything removable there.

Any other suggestions would be appreciated.

Thanks,
Dave

 

[DaveDSR]

Thanks for replying.
The new carb has no adjustment screw, the old carb has an idle mixture adjustment screw but adjusting it through about as wide a range as possible had no effect.
I did replace the tank to carb gasket with a new Briggs and Stratton part. The surfaces that the gasket seals were clean smooth bare metal.
I'll take a look at the diaphragm. Other than cracks or tears is the anything else I should look for?

Thanks again
Dave

 

[DaveDSR]

Appreciate the reply!
You got me thinking. I reread my original post on this thread, and realized that I made a mistake. The engine wouldn't run at all BEFORE I cleaned the original carb. After I did my "thorough cleaning" it ran with the choke wide open, but it surged, or searched, or hunted badly. If I applied a little choke it smoothed out a little. More than a little choke killed it. If I held the throttle linkage steady when it was running with the choke wide open it ran fine, sounded good. Adjusting the idle mixture screw from shut to ready to fall out made no difference. I guess my cleaning wasn't as thorough as I thought it was.

Both the original carb and the new carb have a welch plug sealing the end of the main jet housing. The only place there could be gauze would be covering the screen on the end of the pick up tube on the new carb. I don't remember seeing anything removable there.

Any other suggestions would be appreciated.

Thanks,
Dave

 

[DaveDSR]

Thanks for replying.
The new carb has no adjustment screw, the old carb has an idle mixture adjustment screw but adjusting it through about as wide a range as possible had no effect.
I did replace the tank to carb gasket with a new Briggs and Stratton part. The surfaces that the gasket seals were clean smooth bare metal.
I'll take a look at the diaphragm. Other than cracks or tears is the anything else I should look for?

Thanks again
Dave

 

[bertsmobile1]

Then the main jet is still blocked or the fuel level is too low in the bowl