730 Pump Shot

[NickG]

One thing to consider in the TPI system is that the fuel pressure increases
with lower manifold vacuum. Thus, when you step on the gas a little bit, the
manifold vacuum drops a bit, and the fuel pressure rises a little. When you
go WOT, the greatest change in manifold vacuum occurs, and the fuel pressure
rises to the max setting.

Obviously, more fuel pressure causes more fuel to be sprayed by the
injectors. Maybe that's why the pump shot table has decreasing values as the
%TPS increases. The TBI/'747 setup does not change the fuel pressure
according to manifold vacuum.

Nick

> As the %TPS increases the multiplier decreases.  I would think that as the
> %TPS became larger then you would need more fuel and therefore have a
bigger
> multiplier???  The 747 ECMs pump shot makes sense ... as the %TPS gets
bigger
> the usec of extra pulse width gets bigger.  The 730 seems backwards to me.
>  Can anyone explain this?  The archives and the articles discuss
acceleration
> enrichment out the wazzoo.  But, nobody addresses the layout of this table
> in the 730 and defines what %TPS is and what the Multiplier actually
multiplies.
>  Furthermore, nobody explains the trend in the 730 pump shot table ... as
> %TPS increases the multiplier decreases.  Seems backwards.  I know I am
> missing something ... but, what?
>
> Tim


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