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Craftsman mower with B&S engine, dies when air filter is installed

#1

D

dpnova

To further explain, last weekend when I tried to start my mower, it wouldn't. It didn't seem to have any pressure when I pushed the primer bulb. I removed the air filter, gave it a quick shot of starting fluid and it fired right up but died right away. I started it back up again and kept it running for about a minute by just giving it quick little shots of starting fluid. Once it warmed up it was fine and I was able to mow my lawn. Today I pulled the carburetor off, sprayed it with carb cleaner, blew out all the passages with compressed air, replaced the primer bulb and put it all back together. Now it primes and starts but won't stay running unless I keep pushing the primer bulb, so it seems like it's not getting fuel. I removed the air filter to look inside while it's running and discovered it will stay running without the air filter on. When I install the filter, it dies. It's a new air filter. Any ideas? I can usually fix just about anything but this one has me stumped. Thanks.


#2

reynoldston

reynoldston

dpnova said:
To further explain, last weekend when I tried to start my mower, it wouldn't. It didn't seem to have any pressure when I pushed the primer bulb. I removed the air filter, gave it a quick shot of starting fluid and it fired right up but died right away. I started it back up again and kept it running for about a minute by just giving it quick little shots of starting fluid. Once it warmed up it was fine and I was able to mow my lawn. Today I pulled the carburetor off, sprayed it with carb cleaner, blew out all the passages with compressed air, replaced the primer bulb and put it all back together. Now it primes and starts but won't stay running unless I keep pushing the primer bulb, so it seems like it's not getting fuel. I removed the air filter to look inside while it's running and discovered it will stay running without the air filter on. When I install the filter, it dies. It's a new air filter. Any ideas? I can usually fix just about anything but this one has me stumped. Thanks.
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Vacuum leak, plugged carburetor passage? I would say recheck your work because you missed something. It sound like carburetor to me. No shame in redoing your work, all the years I have been doing it I will still miss things and have to recheck my work at some times.


#3

EngineMan

EngineMan

Recheck the carb again, running better with air filter (new) removed shows its getting a little too much fuel. So check the list below.

Primer Bulb
Check Valve
Primer Line
Backing Plate Gasket
Restricted, Passage


#4

D

dpnova

Thank you for the suggestions. I'm going to order a carb kit for it before I take it apart again. I will post my results.


#5

D

dpnova

Two indications that indicate it was not getting enough fuel were 1) The spark plug was chalky white, 2) I could keep it running if I kept pushing the primer bulb.

I got the new carb kit and I took the carb apart and soaked it in carb cleaner overnight. The next morning I blew everything out with compressed air and put it back together with the new parts and now it starts and runs great. The only thing I noticed that I believe could have been the actual cause was the orfice in the new rubber replacement seat for the needle was twice the size of the old one. Why? Age deteriorated it, or possibly the ethanol in the gas swelled it up even though I have been using an additive that is supposed to prevent this? Don't know for sure, I'm just happy the mower is back to it's old reliable self.


#6

R

Rivets

I believe you are correct when you say that the possible cause is the float needle and seat. Your problem is very common and I replace them in 5-10 carbs a week. I do believe that the cause is the ethanol fuel. We try to get our customers to switch to fuel without ethanol and it has stopped the number of comebacks by 90%.


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