Modern Vespa

Since we had this tiller in repair to fix cracked fuel lines, it never ran again. Checking on it yesterday, I found another cracked line and replaced it--but it still won't run.

There is a primer bubble (top right corner in the picture below) that is supposed to fill with fuel after you press and release a few times, but it never will. All it does is push air out one hose but not suck gas in when I let go. So I'm not sure whether one of the valves is not working, or even whether the hoses were connected incorrectly.

What the picture below shows are the two disconnected fuel lines:
The longer one is going into the primer bubble and was connected to a hole in the tank. When I press the bubble, it pushes air into this hose, but it doesn't suck in gas when I release the bubble.

The shorter hose was connected to the tank nozzle, partially visible just behind the end of that hose. This hose runs to the carburetor. Inside the tank, there is a little cylindrical housing, ending in this nozzle, and I believe there is a valve inside that housing. When I removed the hose from the nozzle, with gas in the tank, gas ran out of the nozzle for a moment and then stopped, reduced to a trickle of drops.

The third, black, hose runs from the primer to the carburetor. This is the only hose of which I am sure it is connected correctly.

My question is, where should those two green hoses be connected? Which one goes to the tank outlet nozzle, which one goes into the hole (also leading to inside the tank)?

I was trying to switch those two hoses but can't, they are the wrong lengths to get it switched. Those two hoses were replaced when it was in repair.

1 hose is the pick up, it will have the fuel filter (little cylindrical housing ) on the end of it. The other is the return line to the tank. If the fuel filter is clogged it will not pick up, the machine needs the filter as it also acts to keep the pick up in fuel regardless of the angle the machine is operating at.
Because the primer bulb isn't returning, more likely the problem is a bad diaphragm in the carb or a stuck check valve also in the carb.
Normally the longer of the two lines is the pick up, if you are not sure, pump the bulb and you should feel vacuum. Again if the is no vacuum, the problem is probably in the carb.
To avoid future problems, run the machine dry if you aren't going to use it for more than a month. Don't rely on stabilizer!

Cheers,
Rob

Thanks, Rob. There is, indeed, no vacuum in the primer when I let go. It doesn't suck in gas.

Could there be a valve in that primer bulb, to not allow gas to be pushed out, but to allow it to suck in? Could that valve be defective instead?

I think I can take the carb off and inspect and clean it. Would any malfunction there be caused by a clogged something, or could something actually be broken (and I might never detect that)?

Actually, from your point of one hose being the return line, I think that line is connected wrong--it goes to the end of the fuel filter. It should instead go into the hole of the bottom of the tank. So I think I need new hoses to be able to reverse them. That will be my next step, I think.

The hose connections were the culprit. Whoever messed with this cultivator did an excellent job: virtually every single hose was connected wrong. The primer couldn't suck in gas and couldn't push it to the carb.

It runs just fine now...

Glad you figured it out, its so hard to diagnose via the internet.
Now get out there and tear up some dirt!

Cheers,

Rob