Craftsman 2.3/16. I am muffed about the impulse

[skippymud]

Hello All

Looking for help. I have a really nice late production red Craftsman 2.3/16 with electronic ignition in hand that does not want to suck fuel

Carb is rebuilt properly and compression is excellent. Fuel line pressure and vacuum tested good at 15psi. Impulse line is clear

What else should I be looking for?

Ken

 

[heimannm]

That is a long fuel line, it can take quite a few pulls to get it going initially, I usually give them a little prime down the carburetor to get things pumping first time around. The impulse signal comes through the carburetor mounting flange, there is no separate impulse line. Do you have the carburetor gasket properly positioned with the impulse passage open?

Beyond that, if the reed is not sealing or the crankshaft seals are leaking you won't build enough pressure differential in the crankcase to drive the fuel pump. I think that model has a detachable cylinder, same story there; if the cylinder is loose the crankcase won't create the pressure differential needed to drive the fuel pump.

Are you sure the fuel pump diaphragm is against the carburetor body and properly oriented?

Mark

 

[skippymud]

Hi Mark

Thanks for your quick response and the info. The mounting flange is positioned properly (impulse hole aligned), reed valve seats nicely, and the diaphragm inside the Carb is mounted properly. So, the saw does run very well if I prime with a 40:1 mix from squirt bottle. With all this, I am thinking the crank seals are weak because once it does run, it runs very well

Ken

 

[skippymud]

Vacuum Test is holding 16in mercury. Pressure Test at 10psi drops very slowly. It takes 16 seconds for needle to fall to 5psi

So the seals are good and the rings, piston and cylinder are in acceptable condition to me

Although the ORIG fuel line held pressure just fine, I decided to put a new one in while I was at it. That ORIG line was really tight in it's meandering pathways through the body of the saw to the Carb. It appears someone in time past cut some off the tip(s) to ensure the line seals to the carb and filter in tank. That's my guess on why the line was so taut. Thanks again for the info! I will reassemble

 

[buzz sawyer]

I remember one saw I replaced the fuel line and the hole into the tank was so small it squeezed the line to where it actually restricted fuel flow. Does that saw has a plastic connector where it goes into the tank? If so, maybe clogged?

 

[skippymud]

It was the Walbro Carb that came on the saw all this time. I installed a Tillotson from a junked Poulan 25DA I have and it pulled fuel and ran like a champ. Since, and because I needed answers, I disassembled both carbs side by side to compare and realized that the diaphragm and gasket were reversed on the Walbro. The Walbro configuration is now correct and the saw runs great. Thanks guys!