[Cousin Andy]

My Sabre's Briggs 14.5 Intek AVS (65 hours) is having some strange problems:

-A bit harder to start than normal
-Bogs under load a lot worse than before
-Blows black smoke when getting bogged down
-when throttle is set to low idle, it lopes, almost sputtering out. Kind-of cycling.

I have replaced the spark plug and I am about to replace the air and fuel filter as a first line measure. I will also check the jet in the carb to see if it's clogged.

Anyone have any other insight? Other things to check? The only other problem I've ever had with this mower is the valve cover gasket, but that was bad from the factory.

Thanks in advance!

 

[Greg]

Cousin Andy,

Welcome!

What year is your Sabre? Only 65 hours? Have you changed the oil lately? Any unusual color?

Model number on the Briggs?

Let us know if the new filters and plug had an effect. Have you adjusted the valves?

Greg

 

[aegt5000]

Black smoke when bogged, hard starting, bad idle.
Sounds like an air filter to me.

 

[MGM]

Choke closed may have come loose or moved or is stuck if an auto choke.

Clogged air cleaner (as stated before)

Float bad or trash in the float valve not letting it close all the way and you are getting a bit of over flow out of the bowl vent flooding the carb all the time.

All would cause a flooding condition (too much fuel).

Black smoke = too much fuel
Bogging = could be from too much fuel
Loping idle = could be from too much fuel
Hard starting = could be too much fuel

A clogged main jet or idle circuit would cut the amount of fuel getting to the engine making it run lean. (Less fuel) with different symptoms

A float valve stuck open just a little would let fuel overflow into the carb through the bowl vent flooding the carb screwing the mixture all to heck through the entire range. On a gravity fed carb (no pump) this could let fuel flood the engine even with it not running, letting fuel get into the crankcase and oil as well.

A dirty air cleaner would increase the vacuum on the carb like closing the choke and well cause the carb to pull more fuel out of the bowl through the jets and idle circuit (rich mixture/too much fuel)

The choke half closed, check the choke cable where it attaches to the choke control arm on the carb if it has a manual choke if not check that the choke opens after the engine has started if it has an auto choke if it is not opening after the engine is started and the throttle lever is not in choke position the reason it is not opening needs to be located and corrected.

A choke issue or clogged air cleaner would let the engine start when cold but would soon flood the engine with excess fuel and would cause it to be hard to start after the first time until the engine was shut down and the excess fuel allowed to evaporate then it would start right up again and again flood out with all the problems you have.

Just a few things to look at.

Bob

 

[Cousin Andy]

Thanks for the ideas, everyone. I went ahead and changed the air filter, fuel filter, and took the bowl off the carb. Turns out there was a dog hair (?) stuck up under the needle valve, I guess that was the main problem. Air filter was pretty dirty too, but it's only been on 9 months. Of course, half my yard is dirt when we're in drought conditions.

Another strange development was the severely cracked and deteriorated fuel lines. The mower is only 3 years old, I would've expected the rubber lines to last longer than that. Luckily I had some spare hose in the garage, and fixed that up.

I guess I'll start doing like I do on my cars, replace the fuel line yearly!