Craftsman tiller vapor lock or ...?

[nomad289]

I inherited a 24" Craftsman front tine tiller with 5hp Briggs and Stratton engine. ~20+ yrs old.

It will start (only using starter fluid) and after a brief idle, it will run full speed and till for about 5 minutes with the choke closed ~1/2 way. Once it is warm it will not run at full speed; although it will start at idle. My guess is vapor-lock or fuel line constriction, what should I do? Blow air thru the line, remove carb and fuel lines, etc ???

It has fresh gas, ran carb cleaner thru the intake, lubricated governer spring, cleaned air filter, etc...

B&S 5 HP.
Model 130202
Type 1907-01
Code 87010210

Thanks in advance.

 

[RandyT]

something that may sound unrelated but the older 5 horse briggs are notorious for floating the intake valve and causing low compression. As the engines warms up the compression gets lower and makes for hard running, can also effect starting. The carb diaphragm may also be weak and need replacing as well as making sure the fuel tank is clean and the fuel pickup is not clogged.

 

[gauthier]

probably needs carb taken off and cleaned and fuel tank cleaned,or,new carb and fuel tank.

 

[nomad289]

Thanks for the advice...
Sounds like I"ll need to pull the carb, check fuel intake, and delve into carb rebuild/replacement if it's not a simple plugged fuel line. Pretty old machine for the effort...
Thanks

 

[gauthier]

Yeah,but it was free,right? and the older the better to work on and get running,they make things cheaper every year,what was a cheap tiller 20 years ago,is something they don't even make now,would cost to much,not meet all the latest epa or what ever guidlines.

 

[Egon]

Twiddle with the high and low carb jets but remember where you started from.

 

[nomad289]

You're right, since it was free I have nothing to lose by trying to fix it...
Does the carb diaphragm act as a fuel pump, operating on the pulsating intake stroke vacumn?
Or does the fuel flow up to the carb via capillary action or venturi effect?
Does the carb have a float bowl and needle valve?

Guess I have some research to do...or take it apart to see how it works...

 

[jbarker855]

If you have the carb I think you have, the diaphragm acts as fuel pump.
If you have the one where carb is bolted directly to top of fuel tank, there is no float bowl and no needle valve. If you have to have choke halfway closed to get it to stay running, the carb certainly needs attention. Maybe only adjustment, but probably needs cleaned. Have fun with it.
-Jay

 

[nomad289]

Yes, I have the carb on top of the gas tank. Thanks--now I understand the purpose of the large tube...it must be the vacumn tube to the fuel pump diaphram. Now that I have a vague idea of how it operates, I"ll be in a better position to disassemble/clean and fix the cause of the problem. Thanks all.