fuel pressure and regulators

[grobbins]

The scheme I often employ when installing a carb'd engine in a EFI'd car, is to
install a "Y" between the pressure and return lines in the engine compartment,
with the 3rd leg going to the carb.. This relieves the high fuel pressure down
to near nothing. With a pressure gauge on the carb leg (and the pump running), I
gradually crimp the return line until the pressure at the gauge rises to around
8 psi. A regulator is then installed to drop the pressure from the 8 psi to
around 4 psi for the carb.

By using the return loop, the pump is constantly circulating fuel, which serves
to cool the pump.

Grant

Bob Cunningham wrote:

> In theory a regulator would work, but I'm not sure they are designed to
> regulate that much of a pressure swing- most of the ones I know of are
> designed to regulate something like 15 PSI down to 7 PSI, I don't think it
> would regulate from 50 PSI accurately and consistantly.  Kinda like a 200
> pound man stepping on a scale made for weighing 35 ton trucks- you're
> outside of the range of the equipment design to count on an accurate
> output.
>
> If you want, the Holley Blue pump is designed for a pretty good flow rate
> at about 15 PSI, and comes with a regulator.
>
> If you insist on using a TBI pump, you might try to regulators in series-
> the first one to get it in the right ballpark, then the second one to
> fine-tune to the pressure you're looking for.  But there's still no
> guarantee with this arrangement, as I'm not positive the first one will
> reduce all the way from 50 to 15.
>
> If you want a small inline pump for a carb, Holley sells one for the
> Projection that is made for a decent flow rate and around 15-20 PSI, then
> you could probably regulate okay from there since you're already in a
> close range.
>
> -Bob Cunningham
> '69 Buick Special w/ 455
>
> > Okay, but this gets to the root of my question.  There isn't a lot
> > of difference in pressure between a carb (7psi) and a TBI (9-13psi),
> > while a TPI pump should put out around 40psi or more.
> >
> > What I'm asking is whether there is any reason I can't use a TPI
> > fuel pump setup for a TBI or carb motor.
>
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