[DeTomaso] Fuel System

Thomas Tornblom Thomas.Tornblom at hax.se
Tue May 26 02:10:36 EDT 2009


Will Demelo skrev:
> I had my car dying after 4000rpm on the dyno last week. I installed a fuel pressure gauge and also determined that the pre-filter was 1/2 clogged.
> The fuel lines are -6 from the bottom of the tank. It's an EFI system, btw. It's running at 46 lbs. At 1/3 throttle (normal driving), the gauge still goes down to ~40lbs. At 4000+ rpm's it goes down to ~36 lbs. It's alot better than the 10 lbs it was going down to before, when the filter was clogged, but is this OK???
> My tuner told me it shouldn't move at all.

It depends on what type of EFI you have. The Ford EFI I'm using keeps 
the pressure differential over the injectors constant, so when I open up 
the throttle, which increases the absolute pressure in the intake 
(reduces the vacuum), the fuel pressure increases with the same amount. 
This vastly simplifies the calculations the ECU has to do as the amount 
of fuel injected is only dependent on the injector pulse width.

I can't say if the pressure drop is a problem for you or not. I assume 
you have a fixed fuel pressure instead of the varying type I'm using. As 
long as the pressure is high enough to properly feed your engine it 
shouldn't be a problem, at least not in theory. You just need to run 
longer injector PW:s.

Where in the fuel system is the gauge plumbed?

> Btw, this same system supported 400rwhp at the wheels last year with the old ECU and 450 rwhp on my old 72 with a carbed stroker.
> Thoughts??
> Will

Cheers,
Thomas



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