Fuel pump questions

[James Tidwell]

At 01:03 PM 12/10/97 -0800, you wrote:
>Fuel splash tends to generate large amounts of vapor that must
>go through the purge canister to eventually exit to the engine.  In 
>theory this should all be accounted for by the EFI system.  In practice,
>you can find driveability problems associated with large amounts of
>purge vapors.
>
>Jim Boughton
>jpb01 at ibm.net
>
>----------
>> From: Bruce Bowling <bowling at cebaf.gov>
>> To: diy_efi at efi332.eng.ohio-state.edu
>> Subject: Re: Re[2]: Fuel pump questions
>> Date: Monday, December 08, 1997 5:07 PM
>> 
>> > 
>> > The return line must have a min of pressure.
>> > All gas tanks have a line at the bottom of the tank, for the pick-up,
>> > and then various others, they can be mounted all over the place.  
>> > I beleive it was some Chry. where they had some mounted on the sides at
>> > about what would be 7/8 full.  On some tanks there is a large trapped
>> > air bubble, all I was making the point was not to let the return line be
>> > covered, if the return is sometimes covered the return line pressure
>> > goes up, the regulator can't bleed the pressure down, and the motor goes
>> > very rich.
>> >   Hope that better explains it   Bruce  nacelp at bright.net
>> > 
>> 
>> I have heard that the return line must exit at the bottom of the
>> tank, so there is no "fuel splash". I think I got this from the
>> JTR book. Is this true? Does it matter?
>> 
>> - Bruce
>> 
>> --
>> -----------------------------------------------------
>> <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>> -----------------------------------------------------
>>                  Bruce A. Bowling
>>                  Staff Scientist
>>    Thomas Jefferson National Accelerator Facility
>>     12000 Jefferson Ave - Newport News, VA 23606
>>                  (804) 249-7240
>> bowling at cebaf.gov  http://devserve.cebaf.gov/~bowling
>> -----------------------------------------------------
>> <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
>> -----------------------------------------------------
>
> Question: Isn't fuel vapor pressure a function of temperature or some
such thing? And if that is the case, then with a closed system (as in the
case of a gas tank with the lid on) the vapor would reach a certain
pressure and remain at that pressure as long as the temp remained the same.
Perhaps minor variations with sloshing, but always returning to the
appropriate pressure for a particular tem.