I posted the below write-up on another forum. I tried to provide as much info as possible to including all the trouble shooting that I did. It was obvious that those that responded to my post either didn't read the whole post or just scanned it. Initially the the tractor would surge at slow RPMs. Weeks later it wouldn't start. As you can see from the write-up I eliminated an electrical problem as the fault by bypassing the carb by putting gas straight down the throat of the carb. The carb and fuel pump were disassembled cleaned and reinstalled with no change in the problem. The write-up also reflected that after the carb was cleaned and reinstalled I was unsuccessful in getting the tractor to start. I then removed the top of the carb while the carb was still attached and there was sufficient gas in the bowl. As before I could get it to start by putting a little gas down the carb throat. I concluded that it was not an electrical problem but a fuel problem. Fuel was getting from the gas tank all the way to the carb bowl. So it would appear that it is an internal problem with the carb. I'm suspecting I didn't clean the carb well or there is an internal leak in the carb. Is there an area in this carb that needs extra attention and is a typical problem area to get completely clean? I understand my original post is indeed lengthy and some won't want to take the time to read all of it. Any help is appreciated.
Below is my original post:
First off this is what I have:
Craftsman Lawn Tractor model 917.270812 with a Briggs & Stratton model 42E707 type 2631-E1 code 9905035B engine.
Here's the problem:
The tractor had been running fine for years then for no apparent (at least to me) reason it started surging at Idle and low RPMs. At higher RPMs it would smooth out. At idle it would smooth out if you choked it a little. OK so it was running a little lean. I made a mental note (not a good idea for me) to remove and clean out the carb. I was too busy and never got around to it - ah heck all I had to do was pull the choke out a little - right.
Well finally it just wouldn't start at all. It would turn over like a champ but wouldn't fire up.
The battery had a full charge and YES it had gas in it. LOL!
I checked for spark at the plugs and there was.
Thought it wasn't getting gas to the carb so I checked the fuel lines and filter and they're good.
So maybe a bad fuel pump? I pulled the fuel line off the pump and gas flowed out the end of the fuel line at the pump end. This was checked after checking the fuel lines so they were empty of fuel so pump must be working.
I put a little gas down the throat of the carb (didn't have starter fluid) and it fired right up and ran great until it ran out of the gas I'd poured in so that eliminated a possible electrical problem.
So now I finally got around to doing that long awaited carb cleaning. I pulled the carb off and disassembled the carb and fuel pump. Cleaned out everything. I've had this unit since the 1990s and there was hardly and debris in the bowl. This was it's first cleaning too. Ran small copper wire through the jets and any small orifices and used compressed air to blow everything out. I reassembled everything and reinstalled the carb.
With a full charge on the battery it turned over like a champ but it still would not start. Nothing changed. It'll turn over but not start at all. Got starter fluid now so I gave it a shot and it momentarily ran until it ran out of the starter fluid. With the carb still installed I pulled the top of the carb off to see if it was getting gas. The bowl had plenty of gas in it so the pump was working fine. So electrical is fine and it's getting gas to and into the carb but that's as far as it gets.
So.... I must not have done a good enough cleaning or it's a bad gasket/internal leak? Any Ideas. The carb is the one that has four screws that hold the fuel pump on. It's not the three screw version. Before I throw money at a carb gasket kit is there a problem area on these carbs that frequently cause this type of problem? I know the kits aren't that expensive but its the down time waiting for the kit that's the problem. If there is a problem area in these carbs that I need to re-clean I can get to that right away.
Your help/advice is appreciated!