| Re: [GMCnet] Fuel tank Sending Unit [message #76816 is a reply to message #76805] |
Tue, 16 March 2010 09:03   |
 |
mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma:
|
Senior Member |
|
|
| GMCWiperMan wrote on Tue, 16 March 2010 06:03 |
Gene,
I've got a question about the last drawing, showing the Aux tank almost
completely filled when going downhill: With the vent line almost centered
fore and aft on top of the tank, won't the absence of a vent behind that
point keep the gas from filling much above that level?
|
I am not Gene, but I'll take a shot at this answer.
It puts fuel into the vent lines. Probably why they put int a fuel/vapor separator. Other than when you first top off, it probably doesn't happen that often. (How many have driven around with bad gaskets around the fuel senders?) It would take a pretty steep hill.
Not exactly what you asked about but related:
My thinking on why GM picked the front tank as the Aux tank.
On rolling hills, the system “pumps” the fuel into the front tank. To explain; on a down hill, fuel flows from the rear tank into the front tank. At the bottom of the hill (as the road levels out) the only fuel to return is the fuel more than the level of the connecting plumbing. (About ¼ tank.) If the switch from downhill to uphill is quick enough, it will “trap” even more of the fuel. (Not many of us drive our GMC's on roads like this... other than Rick D.!) This works best for rolling hills as it keeps at least ¼ tank in the front tank... if you have the fuel. It doesn't work as well on long uphill pulls.
End result is when you are low on fuel, you might need to swap back and forth a few times to keep from running out. It tells you that you should have stopped for fuel sooner.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
|
|
|
|
GMCforum
Search
Help
Register
Login
Home
