fuel not flowing except on prime

[kevxs]

so i did a little colour tuning and checked my sync on sunday and after putting the tank and everything back on I went for a ride but it stalled out soon after and I've been having to drive around with my petcocks on prime to keep it running. I haven't had a chance to take it apart again and make sure my lines aren't kinked or whatever but any other suggestions? the vacuum line is hooked back up to carb boot 2 to my vacuum octy should be functioning.

[BA80]

If you've only got fuel flow on prime the only thing it can be is a fubar octy.

[jetmechmarty]

Make sure there is suction on the vacuum line. Make sure there is no fuel in the vacuum line. Fuel in the vacuum line indicates a ruptured diaphragm. Make sure no lines are kinked. The vacuum shutoff valve is more likely to fail leaking than fail closed.

[jetmechmarty]

If you've only got fuel flow on prime the only thing it can be is a fubar octy.

Not FUBAR. If you desire, it can be fixed, and it's easy enough. Greg is probably one of those who hate it, so he'll call it FUBAR.

I'm am one of those too mentally deficient to turn the fuel off, so I like having the vacuum valve. I'm lucky I remember to shut the engine off.

[kevxs]

any diagnostic tests i can do on it besides checking for fuel in the vacuum line?

[BA80]

Not FUBAR. If you desire, it can be fixed, and it's easy enough. Greg is probably one of those who hate it, so he'll call it FUBAR.

I'm am one of those too mentally deficient to turn the fuel off, so I like having the vacuum valve. I'm lucky I remember to shut the engine off.

Ha ha ha, I took mine off the other day because I got tired of fixing it and it being in the way when I adjust the carbs. I hardly ever shut off the fuel and don't have a problem..........usually. Had a puddle in the driveway this morning though.

[jetmechmarty]

any diagnostic tests i can do on it besides checking for fuel in the vacuum line?

Get yourself some 1/4" hose. Put one to the vacuum port on the spider valve. Disconnect the fuel lines to the carburetors. With the fuel tank all hooked up, apply suction to the vacuum shutoff and observe fuel pouring from the two hoses. If you just suck on that vacuum line, you'll be able to tell if the diaphragm is ruptured. Use a long hose, so you don't risk getting fuel in your mouth.

Before you do that, disconnect the fuel lines from the tank and observe fuel pouring from each tap when you turn the fuel to ON. It's unlikely that both have failed, but check them anyway.