Hello, new here.

I have a 17 plus year old 18HP B&S rider. When I crank the mower, it runs good and strong. However, when I engage the blades, you can tell it looses stamina, and when you cut, especially thick grass, it really bogs down. No smoke or anything like that. I often have to stop and let it catch up before going on. Cutting 2 acres, this is not fun.

I thought it may be the idle adjustment, so I adjusted that till i was blue in the face. nothing.

2 things to note.

I have to always run the mower with full choke, otherwise it will die.

I have adjusted the idle scew while its running, all the way in, and all the way counter clock wise (without removing it), and it doesnt seem to change anything. At full throttle, adjusting the screw has no affect to idle.

I dont mind running in full choke, but I would like to get around the bogging down. What could that be?

thanks

EDIT: Could this be caused by a weak governor spring? I have the front cap off while cutting, and when it bogged down, i jumped off and took a look, and noticed the spring/lever slowly moving back to place, and when it did, it was back to running strong again. I assume thats the governor spring, maybe I should replace that first??

Your first problem has to do with your carburator, having to run your engine on full choke is not a good thing as your engine will starve for air under load. You probably need to take the carb apart clean it out really good and install a rebuild kit. If your engine has a fuel pump then its probably best to rebuild that while your at it. Please provide us with the engine model and type located on the top of your engine shroud.

Ok, will get model info in a couple of hours when I get home.

I did take the carb off and apart last night, it was very clean and float seemed perfect. It has a fuel puemp which I also took apart and appeared good and clean too. But thats not to say it doesnt need a good cleaning/soaking, which I didnt do.

This could also be caused by an air leak, right? could the gas tank cap vacuum problems I have read about cause anything like this? The gas cap is busted, and extremely bad shape, but may be completely unrelated to any of this.


Your first problem has to do with your carburator, having to run your engine on full choke is not a good thing as your engine will starve for air under load. You probably need to take the carb apart clean it out really good and install a rebuild kit. If your engine has a fuel pump then its probably best to rebuild that while your at it. Please provide us with the engine model and type located on the top of your engine shroud.

If it's a 17HP twin cylinder I would think it is only runing on one cylinder. Pull sparkplug wires one at a time to see if it is running on both cylinders.

Your gas cap is defiantly an issue, if your tank isn't venting properly then it can cause problems with the flow of fuel. I don't think the cap is your whole issue though. Check the intake manifold bolts and make sure they are tight, an are leak can cause your motor to run leaner which in your cause you need to use the choke to even out the mixture of fuel/air. Make sure you also check what Tommy suggested as that is another possibility.

Ok, thanks for the info. Was dark when I got home, so will have to test things this afternoon.

tommy, it is the 18HP twin cylinder.

I did get the info on it, here it is.

Model 422707
Type 1214 01
Code 91012832

Ok, need some help. Bought the carb kit.

I soaked, sprayed, blew passages out, etc...

put back together, cranks, runs about 10 secs, and then dies.

I am missing some parts, I am sure. I know now from looking at the parts list now online, I didnt put in the seat with the needle, only the needle. The parts fell out when cleaning, and didnt realize it was there. So i know that is wrong.

I didnt replace the welch plug, do I need to? I cant tell where its supposed to go, but I didnt look hard for it.

I didnt use the foam washer, do I need to? Where does it go if I do need to use it?

Other than that, I am pretty sure everything else is together right.

thanks

well, I think I am hosed now. I pulled carb back apart, and the old seat was still in there, so that wasnt the problem. I kept reading you should replace the seat on a rebuild, so i tried to get it out, and it wont budge. the more i tried, the worse shape the seat is in, and is now unusable, and will NOT budge. I think I am done with this thing, i was only tried to get it to last the season anyway...