Fuel flow issues

[Perazzimx14]

The SP is up and running and several times now going along it will simply shut off. Traced it down with the help of blue/clear fuel line that it seems the petcocks are not passing enough fuel. I have had the petcocks out and the filter are spotless, the screens on the carb fuel inlet are spotless, well over 1/2 tank and also checke the fuel cap for venting.

Yesterday turn right petcock on ride 10 miles to give blood. Get into parking lot shut off right petcock and go into building Come out an hour later turn right petcock on get on the bike and within a mile the bike dies. Turn left petcock on and nothing seems to flow. Turn right petcock to reserve and I can see fuel flowing on right side blue/clear fuel hose. Bike runs and rides fin for the 15 mile loop home.

Any idea's? Also these are new petcocks put on my the PO so I need to verify how long the reserve pipe should be. Which brings up another question how long should the reserve pipe be?

[Chuck in Indiana]

Sometimes, a picture is worth a thousand words.. better have a look at the selector valves.

[acogoff]

     Last season I had or have a similar intermitant fueling problem with the T3. Thought maybe vapor lock from poor -old gas- did not seem to be. Pulled one petcock- nothing wrong. Opened fuel cap while it was acting up and no change. Stuck a small wire in the VHB bowl vents for maybe a blockage there- inconclusive. Lastly I replaced the Yellow tygon type fuel lines I have been using as they were getting old and sticky like the plastic was breaking down. It still could be bowl venting though. And the carburetors have not been cleaned for 30K miles. In my case a full tank of gas would make problem all go away untill 1/2 or less in tank it could happen. Being the lazy type as long as the thing has got me where I am going I have not gone any further into it. Good luck figuring yours out.

[John A]

I was fooling with a hopped up Guzzi with 36 mm PHF's that was disappointing at full throttle.  Everything checked out and I was thinking that I couldn't even tune a gasoline engine.  I ended up drilling out the internal passages of the petcocks and banjos.  It helped but it's possible that I disturbed an unseen blockage in there somewhere.  It shouldn't have made a difference, drilling out the passages,  they don't flow that much fuel but it is gravity fed so maybe.

[bodine99]

Tank-bag blocking cap vent?? Are they vacuum operated? low signal closing valve? Pingle passes more gas!!!!

[Antietam Classic Cycle]

The SP is up and running and several times now going along it will simply shut off. Traced it down with the help of blue/clear fuel line that it seems the petcocks are not passing enough fuel. I have had the petcocks out and the filter are spotless, the screens on the carb fuel inlet are spotless, well over 1/2 tank and also checke the fuel cap for venting.

Yesterday turn right petcock on ride 10 miles to give blood. Get into parking lot shut off right petcock and go into building Come out an hour later turn right petcock on get on the bike and within a mile the bike dies. Turn left petcock on and nothing seems to flow. Turn right petcock to reserve and I can see fuel flowing on right side blue/clear fuel hose. Bike runs and rides fin for the 15 mile loop home.

Any idea's? Also these are new petcocks put on my the PO so I need to verify how long the reserve pipe should be. Which brings up another question how long should the reserve pipe be?

There should be no pipe in the reserve hole, the pipe in the main feed hole is usually ~ 50 mm total length.

Make sure the gasket inside the petcock isn't rotating with the lever and blocking off the flow or disintegrating and doing the same.

[Perazzimx14]

There should be no pipe in the reserve hole, the pipe in the main feed hole is usually ~ 50 mm total length.

Make sure the gasket inside the petcock isn't rotating with the lever and blocking off the flow or disintegrating and doing the same.

Yeah I worded that wrong about the reserve pipe but will check the 50mm lenght on the main feed. I'll also check the gasket hasnt squished or moved partiall blocking the opening.


To the others, No tank bag, brand new fuel lines 2 days ago, Petcocks pulled 2 days ago and filter screens are white and as clean as the day they were pruchased. Carbs were ultrasonically cleaned back in early February when I was going through the bike.