Fuel delivery problem
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Grand HDF Member
Joined: Nov 2012
Posts: 3,784
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From: Pasadena TX
Fuel delivery problem
My wife's bike quit last week and I'm diagnosing my trouble today. This bike is carbed. The petcock is vacuum operated. I removed the fuel line to the carb and routed another line to a gas tank. I removed a gas cap, put the selector on main, and pulled a vacuum on the petcock. Nothing. I switched to auxiliary tank and some gas flowed, but soon quit after a cup full or so. I guess the next step is to drain the tank and pull the petcock. Maybe a clogged filter, maybe a failed diaphragm in the petcock. Is my reasoning sound, or am I overlooking something?
Seasoned HDF Member
Joined: Apr 2011
Posts: 6,185
Likes: 2,134
From: W. Texas
When you pulled the vacuum on it did it hold the vacuum ?? If not that's a problem to address.
Many of us have done away with the vacuum operated pet ****.
You will get a look at what filter it has when you pull the petcock.
Hard to imagine it could be that clogged with getting some fuel out on reserve.
WP
Many of us have done away with the vacuum operated pet ****.
You will get a look at what filter it has when you pull the petcock.
Hard to imagine it could be that clogged with getting some fuel out on reserve.
WP
Thread Starter
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Grand HDF Member
Joined: Nov 2012
Posts: 3,784
Likes: 100
From: Pasadena TX
Originally Posted by WP50
When you pulled the vacuum on it did it hold the vacuum ?? If not that's a problem to address.
Many of us have done away with the vacuum operated pet ****.
You will get a look at what filter it has when you pull the petcock.
Hard to imagine it could be that clogged with getting some fuel out on reserve.
WP
Many of us have done away with the vacuum operated pet ****.
You will get a look at what filter it has when you pull the petcock.
Hard to imagine it could be that clogged with getting some fuel out on reserve.
WP
Dirt don't hurt
Joined: Jan 2011
Posts: 21,065
Likes: 4,561
From: Haslet Texas
There are rubber parts that are in the OEM petcock that when they wear out you have to rebuild/replace the petcock before it will pass fuel no matter how much vacuum you put on it.
Seasoned HDF Member
Joined: Jan 2015
Posts: 15,990
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From: Sandy Eggo's North County
You don't say what year your wife's bike is. If it's a 1996 or before, then there's a recall for that petcock diaphragm. The original diaphragm doesn't like MTBE nor ethanol.
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Grand HDF Member
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From: Pasadena TX
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Club Member
Joined: Jun 2007
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From: Bedford UK
John, if the petcock is original it's almost 20 years old! I'd be inclined to replace it with a non-vacuum type anyway, while checking for other related problems. I have a Pingel, however the older factory stock style of taps are available new for much less.
