petcock
Thread Starter
|
Intermediate
Joined: Mar 2011
Posts: 43
Likes: 0
From: Alabama
petcock
guys trying to remember, on fuel petcocks with vacumn if you turn fuel on or reserve should fuel start to flow, or does engine have to be turning over to create vacumn to make fuel flow?
Road Captain
Joined: May 2007
Posts: 579
Likes: 1
From: eastern NC
your kidding right?
If you have a petcock then you have a carburetor with a float, the fuel flows out of the tank by gravity and the float shuts the fuel flow off when it reaches its set point.
The engine has to be turning over to pull fuel through the venturi in the carb and into the engine.
If you had fuel injection there would be no petcock and there is an electric fuel pump inside the tank.
If you have a petcock then you have a carburetor with a float, the fuel flows out of the tank by gravity and the float shuts the fuel flow off when it reaches its set point.
The engine has to be turning over to pull fuel through the venturi in the carb and into the engine.
If you had fuel injection there would be no petcock and there is an electric fuel pump inside the tank.
Thread Starter
|
Intermediate
Joined: Mar 2011
Posts: 43
Likes: 0
From: Alabama
Well this one starts flowing as soon as fuel is on or reserve..no cranking req. this dont seem right..I thought that was the purpose of the vacumn line
Trending Topics
Tourer
Joined: May 2009
Posts: 389
Likes: 3
From: Third Coast TX
Turn the petcock to off, remove the fuel line from the petcock and loosen the petcock just enough to be able to turn it so you can access the four phillips screws on the back side where the vacuum diaphragm is. Hold the diaphragm housing to the petcock while removing the screws, there is a spring that will try to push off the housing you are removing. As you remove the housing from the petcock, notice where the spring is in relation to the diaphragm? Put the spring on the other side of the diaphragm and reassemble.
Here's a link with photos..you can do this while it is still installed in the tank : http://crapmods.com/phpBB3/viewtopic.php?f=16&t=8954
Last edited by Freebee; May 15, 2011 at 07:54 PM.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Road Captain
Joined: May 2007
Posts: 579
Likes: 1
From: eastern NC
You have a "Failed Ptecock" there's a reversal procedure to bypass the vacuum diaphram take like 15min. however it will be manual off / on from that point on.
Turn the petcock to off, remove the fuel line from the petcock and loosen the petcock just enough to be able to turn it so you can access the four phillips screws on the back side where the vacuum diaphragm is. Hold the diaphragm housing to the petcock while removing the screws, there is a spring that will try to push off the housing you are removing. As you remove the housing from the petcock, notice where the spring is in relation to the diaphragm? Put the spring on the other side of the diaphragm and reassemble.
Here's a link with photos..you can do this while it is still installed in the tank : http://crapmods.com/phpBB3/viewtopic.php?f=16&t=8954
Turn the petcock to off, remove the fuel line from the petcock and loosen the petcock just enough to be able to turn it so you can access the four phillips screws on the back side where the vacuum diaphragm is. Hold the diaphragm housing to the petcock while removing the screws, there is a spring that will try to push off the housing you are removing. As you remove the housing from the petcock, notice where the spring is in relation to the diaphragm? Put the spring on the other side of the diaphragm and reassemble.
Here's a link with photos..you can do this while it is still installed in the tank : http://crapmods.com/phpBB3/viewtopic.php?f=16&t=8954