Cold fuel

[Bruce]

You've hooked up a visual flow guage and have seen this, or are guessing?.
If you vapor locking fuel at 35 PSI there are some serious issues.

Last I hear the low end aromatics were about 130dF flash temps., and that's
at atmospheric pressure.

If you fuel temps are approaching an actual operating temp of 120, I'd be
looking for some Firebraid.  Are you using lots of AN?.  AN has been
nicknamed the Heat Magnetic with some people.

Some oem fuel routing is just flat dumb, ie in 3rd gen Fbods (CCC), the fuel
line runs with in 2" of the trandy for 2'.  Up in the tranny tunnel is great
place for heat to accumulate.
Bruce




----- Original Message -----
From: "Tom Sharpe" <twsharpe at mtco.com>
To: <diy_efi at diy-efi.org>
Sent: Wednesday, October 17, 2001 10:22 PM
Subject: Re: Cold fuel


>
>
> Bruce wrote:
>
> > With wet manifolds, might have a problem with the fuel being too warm
(also
> > remember in carb applications you have to allow for fuel volume).   So
they
> > can have ****TOO**** much of a good thing (vaporization).
> >
> > On EFI (port), just about the opposite is true.  You can have trouble,
er,
> > you can sometimes improve performance by aiding with fuel vaporization.
> >
> > If you look at the latest GM manifolds, and heads you can see where they
are
> > making a real effort to get as much fuel on the back of the valve head
as
> > possible.
> >
> > Honda F1 in years last ran a fuel preheater, to aid in vaporization.
> > Bruce
>
> On a 95 deg summer day running around elkhart lake for 60 min., after 45
min.
> everything was hot - track temp > 120, the fuel in the rails boils when
you let
> off the gas going into a corner and the fuel pressure drops to match the
engine
> vacuum. When you step on the gas exiting the corner, it's just like a carb
w/
> vapor lock. it takes about two seconds full throttle to clean out the
rails....
> maybe my bigger fuel pump will make the problem worse.  IMHO, heating the
fuel
> will produce better mileage/power/combustion, I like the new, non-recycle
efi
> fuel systems. The bypass ones really heat the fuel... Tom
>
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