Love This

[Greg Hermann]

>I think you should check the temp of your fuel after about 30 minutes
>running it should be 20- 30 deg less than the coolant temp, remember most of
>the fuel is being returned (hot) to the tank at normal driving, The major
>problem is keep the pump from running dry and tearing up the pump.

YO--

The old Bosch D-jetronic systems on Volvos would vapor lock AT WILL on
account of heating up the fuel in the tank too much under sustained high
engine load. And I mean the electric pump at the back not even being able
to lift the fuel out of the tank to itself. Fuel in the tank almost
literally boiling!!! Not running the pump dry was NOT the major problem
HERE!!!

Regards, Greg
>
>The "no return" systems came into favor as a result of more restrictive
>rules on evap system's. If the fuel isn't returned to the tank the vapor
>pressure is much reduced because the fuel is no at ambient temp, (except for
>bone head door stop Camaros that have the tank in top of the muffler).
>
>
>Ward
>
>
>-----Original Message-----
>From: owner-diy_efi at efi332.eng.ohio-state.edu
>[mailto:owner-diy_efi at efi332.eng.ohio-state.edu]On Behalf Of Greg
>Hermann
>Sent: Sunday, January 31, 1999 8:22 AM
>To: diy_efi at efi332.eng.ohio-state.edu
>Subject: RE: Love This
>
>
>>> >I know Toyota uses the system in the 1ZZ-FE and claims lower evap
>>> >emissions as the reason, FWIW. Less vapor lock?
>
>Keeping the fuel in the tank cooler keeps its vapor pressure down, and
>helps reduce evap emissions. Yes, keeping the tank cooler also provides
>more net positive suction head (NPSH) to an in line fuel pump, but it does
>nothing to help with keeping fuel vapor out of the fuel rails during
>hard/hot running or after a hot soak.
>
>With no bypass fuel flow, this second problem WILL be worse.
>
>Greg
>>>
>>> DO NOT let mfgr BS about less evap emissions get confused with getting
>the
>>> vapor bubbles out of the fuel rails!!!
>>>
>>The evap. test has been increased from 1 hr to 3 days so is more
>>difficult to past.  Does any one know where i can get a low
>>permeation fuel neck hose?
>>alex