Petcock vacuum?

[hornetgod13]

I have troubleshot a fuel delivery problem down to the petcock vacuum. A new fuel pump, and a rebuilt petcock have not improved the problem. I did test the petcock after it was rebuilt. While manually sucking on the vacuum hose, it will open and allow fuel to pass however, on the motorcycle it will not. The vacuum hose is intact and free of blockage. It holds pressure if I pinch it however, if I blow in the vacuum line down through the intake vacuum metal lines when its un-pinched, it merely hisses and does not hold pressure. Is it common to have vacuum leaks effect petcock operation?

[hornetgod13]

I realized the lack of petcock vacuum and blow back leak down was most likely due to the carbs being removed at the time of the test. Once everything is reassembled, I will test the petcock operation again.

[hornetgod13]

I found a pinched/colapsed vacuum line under the carb/black manifold mat. That line also had a hole melted in it. Replaced the line and reinstalled the carb. I have plenty of fuel flow from the petcock now.

[kane67]

Hi,

Was it the ”orange” hose?
https://www.google.com/search?q=gl1500+ ... gU0VL4OjeM

Br, kane

[hornetgod13]

Yes, it was the orange hose. Right at the 90 degree bend.

[kane67]

Ok, orange hose goes to ECU so a fresh good hose may improve engine behavior...

[Wing--Man]

Hornetgod:
You will find a PIN HOLE right at the red arrow.
Either get a new one or NAPA has thicker wall hose by the foot. Tho you will need a longer piece than OEM for the extra loop.

Check the LARGE hose directly in front of the carburetor on the same side, you may find the same issue.



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