350TPI Fuel Consump Problem

[Bruce Plecan]

> The car is an 86 Fiero with a crate 350TPI and 5-speed. Its closest
> equivalent is probably a '90 350TPI in a F-body. Problem is the fuel
> consumption sucks, expecially in traffic: 12MPG. On the road it does 20+.

At idle, with car not moving hard to get good mileage.
Does program have a C/L idle, disable?

> At idle, integrator readings range from 130 to 140. Block learn seems to
be
> pinned at 160 (this is the mac, right?) Earlier somebody asked (I think
> Shannen) about fuel pressure. I think I said 40 or 41 lbs, but I lied. So
> much for my lack of thorough note taking (Bruce, you were right). The fuel
> pump is seeing about 0.6 vplts lower than battery (my cutoff switch wiring
> is probably responsible)

Get that fixed first.

> So today I started again from scratch. With fuel line pressured up and
> engine not running pressure is about 42 lb. (and stays there... no leaks).
> Started engine and pressure drops to 36 lbs and stays there. I think this
> is much too low.

Quit thinking <<g>>.

> Took the car out on I75 this afternoon and found following at 65 to 80mph:
> 1. Integrator drops nicely into mid 120s.
> 2. Block learn starts dropping and even gets into 140s... nice sign. Also
> found that when punching the gas the block learn quickly drops into the
120
> to 130 range and then in a second or two begins to rise into 150s. I
assume
> this may be the ECM detecting a lean condition and then eventually trying
> to compensate for it.

That light and small of car no were near the aero load as anything else, try
less fuel, gain using the tuning doc stuff.

> Getting back to the fuel pump, is my FI system starving because of lack of
> high enough pressure and then trying to compensate?? Will appreciate some
> feedback on this. Another question: If the FI is starving what is a quick
> way to determine if its the fuel pump or prseesure regulator opening
early??

most FP problems manifest themselves at or near WOT, or AE
Bruce
>
> Still have to answer Shannen's question about running with O2
disconnected.
> Need to jack car with floor jack to get to connector but the sciatic nerve
> suggested today was not the day to do this.
>
> Thanks for the help!
>
> Don
>
>
>
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