Stihl 034AV

[Mad Professor]

I’ll be doing a pressure test when I get the time. What is the reasoning behind a leak causing the impulse to not work properly?

crankcase suction/pressure is what make the pump diaphragm pump.

I know about the screen, fuel will flow to the metering side without the screen but with the screen it doesn’t flow. I tested it without the screen figured it wouldn’t make a difference just to see if it would run

Seems that the screen is clogged. Clogged screen = no gas to carb. Fix that first before you go chasing your tail........

Did you actually try to run it without the clogged screen?

 

[Homer6679]

I did try and run it without the screen, no dice

 

[Mad Professor]

Will it fire with a squirt of mix in the carb?

 

[Vintage Engine Repairs]

Your question and subsequent info shared is too vague, I’d suggest watching this and then coming back.

 

[Vintage Engine Repairs]

Pics of the metering and pump diaphragms. Both seem to be in good shape to my knowledge. Both are pliable

That metering diaphragm isn’t in good shape.

 

[Tobystihl]

034's are prone to impulse pipe failure over time!

 

[Homer6679]

A little belated but I got the 034 running today. After a tear down of everything but splitting the case, cleaned everything and put it back together it ran after a couple pulls on choke and some carb tuning. Vacuum test resulted in no leaks. I did notice that the tank breather screw was screwed all the way in. I backed it out a little was the only thing I changed other than cleaning. Could not letting the tank breathe or breathe as much have been my issue the whole time?

 

[pioneerguy600]

The grub screw style tank vents are not meant to be screwed/twisted in, they cut threads that way. They should just push in allowing air to bypass the grub screw around the threads but that won`t happen if the threads are blocked from cutting into the walls of vent line.

 

[Homer6679]

It’s not a vent line, it’s a plastic piece