Briggs 13.5 hp riding mower engine suddenly flooding?

Reply

  #1  
Old 06-08-15, 08:34 AM
Member
Thread Starter
Join Date: Dec 2001
Location: Duluth, GA
Posts: 76
Angry Briggs 13.5 hp riding mower engine suddenly flooding?

Son's riding mower was running well and suddenly shut off with a bang. Gasoline flooding the intake. Online info for mower number 13AC762F729 says the engine number is 752B2453G2 but a B&S search on this number comes up with 21B807-2453-G2 for this engine. Looks like a Nikki carb which we took off and examined. I found the float fuel shut-off valve allowed the float to go the whole way to the base of the carb before seating.

This carb has a plastic fuel fill section and jet suction tube that sticks down in the carb bowel and examining the full fill tube section I don't see any special seat for the shut-off valve to seat on. Should there be one? It only has the plastic to seat in and no way to make any float level adjustment. Looking at the rebuild kits for this type of carb I don't find any ring and seat listed that might go up inside this inlet tube.

Can't figure out what else may be causing the flooding and any words of wisdom would be greatly appreciated.
 
Sponsored Links
  #2  
Old 06-08-15, 10:30 AM
cheese's Avatar
Forum Topic Moderator
Join Date: Jul 2001
Location: USA
Posts: 16,815
There is no seat in that plastic insert, the needle just seats against the plastic hole. Usually when these carbs flood, it's because there is trash obstructing the needle or the o-ring above the fuel inlet on the plastic piece has broken or pinched. Be careful to not lose the brass jet down in the center of the plastic piece. It often falls out and the engine will flood badly while running without it.
 
  #3  
Old 06-08-15, 11:00 AM
Member
Thread Starter
Join Date: Dec 2001
Location: Duluth, GA
Posts: 76
Thanks Cheese. Understand how dirt could keep the valve from seating but I'm used to inlet valves closing when there about mid level in the carb bowel, this thing doesn't do that. Out of curiosity, I tried installing the fill valve above the slotted plastic in the float that the little head on the valve would fit into. This closed the valve when the float was moved up only slightly. The engine started and ran fine at idle with a little choke applied and no gas was flooding the intake. Since it no longer flooded everything, I'm assuming the multi-ringed O ring that sits on top of the plastic piece is still good. That brought me to trying to figure out what piece could have failed all at once.

Should add that I re-installed the valve correctly and it flooded everything again.
 

Last edited by sjc1701; 06-08-15 at 11:09 AM. Reason: Added note
  #4  
Old 06-08-15, 03:03 PM
Member
Join Date: Dec 2006
Location: Canada
Posts: 528
  #5  
Old 06-08-15, 08:12 PM
cheese's Avatar
Forum Topic Moderator
Join Date: Jul 2001
Location: USA
Posts: 16,815
Based on that, I'd say you should replace the needle then.
 
  #6  
Old 06-14-15, 12:00 PM
Member
Thread Starter
Join Date: Dec 2001
Location: Duluth, GA
Posts: 76
Well, I purchased a Nikki carb rebuild kit that included the plastic float and part the holds the float and main jet and main jet and 'O' ring. All did not go well. Put everything in and the engine wouldn't start. Eventually determined the shutoff solenoid wasn't allowing fuel to enter the main jet! I removed the plastic tip from the shutoff, re-installed and the engine fired right up. Ran well from idle to about 3/4 throttle, but from there to full throttle it would stumble like it wasn't getting enough fuel. Disassemble again and pulled out the main jet which allowed the engine to run from idle to full speed but was to rich. The hole in the main jet I received in the kit looked awfully small to me and it wouldn't run right with it anyhow, so what the heck, drill it out bigger! the smallest bit my son had on hand was a 1/16 so that's what we used. With that installed the engine starts fine and runs perfect up to about half throttle and it has enough load capability to run the blades and move the tractor at speed.... at least runs well enough to cut grass. Seems so close to being right but what to do. Is 1/16 still to small? to big? or is it something else that makes the engine stumble going on up to full throttle?
 
  #7  
Old 06-14-15, 05:35 PM
cheese's Avatar
Forum Topic Moderator
Join Date: Jul 2001
Location: USA
Posts: 16,815
Something else is wrong with the carb, but you will need another main jet once you get it fixed because you made the hole too big. You have some sort of restriction still from the sound of it.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes