Last year when I got this, it wouldn't run at fast idle unless choke was on. I replaced the carb, fuel, filter, etc and it ran great for the rest of the year. This year it ran fin until about a month or so ago and now to run at fast idle, it runs rich, with a bit of black smoke out the exhaust. If i slow the idle down, it runs smooth, just less power when mowing. Plug looks OK, just black and sooty, I added some Stabil and it helped a little, tried draining gas and using fresh stuff (no ethanol) but still running rich. Got a new air filter and another set of plugs to try next but open to ideas.. I suppose a different carb??
- Joined
- Sep 24, 2017
- Threads
- 266
- Messages
- 6,633
what Make and Model engine do you have on it?
www.lawnmowerforum.com
Hey New Members
from one member to another, welcome to Lawn World! Want to help us help you? Post your equipment's model numbers in your help thread. Saves us time, and gets you answers quicker. Don't know where to find your equipment Model & Type numbers? Here are links as well as pictures to guide you. Honda...
www.lawnmowerforum.com
I believe it is a B&S 19 hp # 31Q677 0134 B1 according to the valve cover no stickers on the motor, looks like they were removed before I got it.
carb is this from Amazon
https://www.amazon.com/dp/B07JFWZCTX?psc=1&ref=ppx_yo2ov_dt_b_product_details
Part number on carb was from an engine website (parts tree) and looked up part number on Amazon (594605)
carb is this from Amazon
https://www.amazon.com/dp/B07JFWZCTX?psc=1&ref=ppx_yo2ov_dt_b_product_details
Part number on carb was from an engine website (parts tree) and looked up part number on Amazon (594605)
update: I pulled the air filter and replaced it, the old one felt quite a bit heavier than the new one. ???? also put a new spark plug on. Hopefully trying it out later today...
Son cut the grass and it still seems to bog down when making turns with the blades engaged. The throttle lever acts flooded until it is about 3/4 back from fast stop. Choke seems to be shutting off correctly,maybe wrong jets in carb??
Son cut the grass and it still seems to bog down when making turns with the blades engaged. The throttle lever acts flooded until it is about 3/4 back from fast stop. Choke seems to be shutting off correctly,maybe wrong jets in carb??
Last edited:
Carb arrived today, hopefully get it installed tomorrow, drain the fuel and put fresh fuel in (just a good idea) and see how it works. I am thinking the carb I installed before said it would work, but it also said it was for a 18 HP motor instead of a 19 HP. This one says 18-20HP motor. but both carbs list the motor number in the description. We shall see if it helps.
bertsmobile1
Lawn Royalty
- Joined
- Nov 29, 2014
- Threads
- 65
- Messages
- 24,995
A carb is a carb is a carb
There is almost no difference between a carb for an 18 hp engine and one for 20 hp.
IF the choke size is too big then you get poor acceleration
If the choke size is too small then it will not idle down
If the main jet is too big then the engine will flood when accelerating
If the main jet is too small it will run lean at WFO
All carburettors are designed to supply fuel at around a 14:1 ratio ( 14 volumes of air to 1 volume of fuel )
After that is simply things like the size & position of the throttle lever compared to the governor arm movement .
The quick & dirty test is to slide the carb off the studs. bolts leaving the fuel line attached
Turn it sideways and blow high volume low pressure air through the carb from the air filter side
If the carb is functioning properly you should get a fine stream of atomised fuel bowing out the engine end of the carb .
There are only 2 aways you can be certain ( mostly ) that you get a good carb and that is to buy an original one from a dealer or a certified after market one from a non-franchied mower repair shop like Star, Scrubbie or myself
Every other source is a lucky dip with a 70:30 chance of you being unlucky
Alibaba is a good source where the carbs will usually work but they often do not know what the carb really fits and the information is often wrong
Carb arrived today, hopefully get it installed tomorrow, drain the fuel and put fresh fuel in (just a good idea) and see how it works. I am thinking the carb I installed before said it would work, but it also said it was for a 18 HP motor instead of a 19 HP. This one says 18-20HP motor. but both carbs list the motor number in the description. We shall
I could be tearing down the motor and do a complete rebuild to make sure it is dead on spec, but it starts and runs, so....
New carb seems to be working better than the last one right now, time will tell. The choke plate looks to have an extra hole in it, not sure that would make a difference once it starts and the choke plate is open, which is where it normally runs (mechanical choke) We'll drive it a few months and see how it works.
Thanks for the words of wisdom. bertsmobile1
I agree, for years I have rebuilt carbs for snowmobiles and I am just plain tired of doing it anymore (vintage sleds) When I first changed the carb, it ran great until it sat over the winter, and a few months after, it worked OK. suddenly it stated acting up and I did the drain and refill with fresh non-ethanol gas thing, ran chemicals thru it, etc. so we will see how this one works. I just don't have the desire to tear the carbs down and try to find out the factory jet sizes, etc. Just want to cut the grass which is growing too much because of all the rain.
I could be tearing down the motor and do a complete rebuild to make sure it is dead on spec, but it starts and runs, so....
New carb seems to be working better than the last one right now, time will tell. The choke plate looks to have an extra hole in it, not sure that would make a difference once it starts and the choke plate is open, which is where it normally runs (mechanical choke) We'll drive it a few months and see how it works.
Thanks for the words of wisdom. bertsmobile1
Last edited:
Well, second round of cutting grass and it seems to be working great! I may have gotten lucky and got a good carb, or it may run for awhile and have issues like the last one. We shall see. for now, I am happy.