Primer Blub Required For Each Start.


  #1  
Old 06-15-14, 11:12 PM
B
Member
Thread Starter
Join Date: Jun 2014
Location: USA
Posts: 2
Upvotes: 0
Received 0 Upvotes on 0 Posts
Primer Blub Required For Each Start.

B&S 12H807 1530-21 on a Snapper 21 Self Propelled walk behind. Installed carburetor overhaul kit #498260. Now every crank requires primer blub use before the engine cranks, it has no choke or jet adjustments. This mower sat for a long that so I can't remember if this is/was normal operating procedure. Once it cranks it runs fine. I did not replace the old primer blub, could that have anything to do with my issue? TIA for any help received.
Bob Helms
 
  #2  
Old 06-16-14, 05:38 AM
M
Member
Join Date: May 2006
Location: Iowa!!!!!
Posts: 3,853
Received 36 Upvotes on 35 Posts
For other than normal operating temps on an engine it will need a richer mixture from somewhere - either a choking system or a primer system.

Does yours have a choke of some kind or is it just the primer bulb? A choke would have two plates in the carb throat - a throttle and a choke plate. The latter would be to the air intake end of the carburetor.
 
  #3  
Old 06-16-14, 09:13 AM
G
Member
Join Date: Jun 2006
Location: United States
Posts: 2,296
Upvotes: 0
Received 31 Upvotes on 29 Posts
While it is running spray/dribble some carb or brake parts cleaner behind the carb, if the engine tempo changes the carb to intake gasket may be leaking and it is sucking air from there rather than through the carb. Have a good one. Geo
 
  #4  
Old 06-16-14, 10:48 AM
B
Member
Thread Starter
Join Date: Jun 2014
Location: USA
Posts: 2
Upvotes: 0
Received 0 Upvotes on 0 Posts
This engine does not have a choke. It only has a primer blub. There's only one plate in the throat of the carb, managed mostly by the governor. The breather / carb assemblies have new gaskets. The primer bulb was not replaced. Priming is required to start even when the engine has just been shut off. The owners manual states that it should start on it's own while warm but cool weather may require repeat priming. Thanks for your help.
Bob Helms
 
Attached Images  
  #5  
Old 06-16-14, 01:09 PM
M
Member
Join Date: May 2006
Location: Iowa!!!!!
Posts: 3,853
Received 36 Upvotes on 35 Posts
The bottom line is the mixture without the primer is too lean to start on.

Not changing the primer bulb may be a problem if there is some kind of air leakage around it.

If what Geo suggested doesn't get you any answers, there could be a restriction in the fuel passages in the way of varnish since it has sat for some time. that can be cleaned out with Sea Foam.

A lawn mower should have an air filter. Make sure that is a good one. It will provide a certain amount of ramp up to the vacuum in the carb throat and get you a richer starting mixture.

The other possibility is a weak spark which needs a richer mixture than normal to fire.

I guess, if it was mine, I wouldn't spend too much money to fix it if I could get it started with the primer.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: