82 Gs550, carb not pulling fuel/or petcock

[Johnhaley]

So I removed my tank to clean it up and replace the gasket and washers on the petcock. I tested the petcock for flow on prime and on on before putting the tank back on. I put the tank back and on the bike and it initially fills the line and bowls. IÂ’ll start the bike and run it on idle for 5 minutes and it starves. (Yes the vacuum line is connected) IÂ’m obviously somewhat of a novice and IÂ’m probably overlooking something simple. Any troubleshooting ideas?
Bike was running fine before I took the tank off.

thanks,
John

[rphillips]

What pos. is the pet cock in?? when starving.

[Johnhaley]

Prime and on

[rphillips]

Uh, Uh, Uh, Uh, Seems strange from what you did. Raise rear of tank & unhook fuel line from pet cock,. turn to Pri., if fuel flows full stream the problem is something farther down.

[Johnhaley]

Uh, Uh, Uh, Uh, Seems strange from what you did. Raise rear of tank & unhook fuel line from pet cock,. turn to Pri., if fuel flows full stream the problem is something farther down.

I thought it was strange too. I tested the flow on prime and it flows freely when not attached to line, if I attach the line and hold the tank up, it will flow also, but nothing in the on position when attached.

[rphillips]

There's "GOT TO BE" be vacuum on the small line at the pet cock to make the fuel flow when in "ON" position. That's how they work, when in "ON" no vacuum (eng. not running) fuel is automatically shut off, vacuum on (eng. running) fuel is automatically turned on. If you connect a piece of vacuum line to the vacuum port, you can lightly suck on it to see if fuel flows as designed in "ON" pos.

[Johnhaley]

There's "GOT TO BE" be vacuum on the small line at the pet cock to make the fuel flow when in "ON" position. That's how they work, when in "ON" no vacuum (eng. not running) fuel is automatically shut off, vacuum on (eng. running) fuel is automatically turned on. If you connect a piece of vacuum line to the vacuum port, you can lightly suck on it to see if fuel flows as designed in "ON" pos.

Roger that, the vacuum tube is connected, it has suction and yet no fuel flow in the ON position. Even in the PRIME position the flow will stop and the filter and fuel line will empty into the carb and a few minutes later the bike will quit (obviously). Perhaps the vacuum is blocked inside the petcock? Seems unlikely but that’ll be my next inspection.

[rphillips]

On Prime the fuel should flow full stream constantly, vacuum or no vacuum, vacuum has nothing to do with that position.

[Johnhaley]

On Prime the fuel should flow full stream constantly, vacuum or no vacuum, vacuum has nothing to do with that position.

Thanks, I understand the general functions of the system, what I don’t understand is why when I put the tank back on it would no longer function when no changes were made. It flows freely in PRIME and with good suction in ON, the line just stops filling. Does the system need to be downhill? (Gravity fed) As it is now, the filter on the line sits on top of the carbs making it almost parallel with the ground and not so much downhill. Will that effect the function?

[cowboyup3371]

Yes get rid of the filter as you don’t need it and it is likely too restrictive. The petcock has one and there are screens in the carbs as well.

[Johnhaley]

Yes get rid of the filter as you don’t need it and it is likely too restrictive. The petcock has one and there are screens in the carbs as well.

I was thinking about that, thanks!