[Diy_efi] Re: CIS EFI via Fuel Pump PWM

[Kenny W]

Quoting Kenny Bauman <kennybauman at yahoo.com>:

> Not sure I understand the 100:1 range needed of
> the
> pump.
> 
> Perhaps you can clarify?

I think that's a little extreme, as actual efi systems 
rarely if ever vary duty cycle from 1 all the way to 
100%, which would be varying fuel delivery in a 100:1 
fashion. I think the main issue with making this work 
has been covered, that the pump response would be an 
issue wrt to it's intertia and overall damped step 
response. It makes more sense to run the pump 
constantly and switch somthing that has a better time 
constant both electrically and mechanicaly. Another 
issue is that fuel in the lines after you shut the pump 
off will dribble out of the injectors, you need some 
sort of positive shutoff. You'd need a solenoid valve 
located as close to the injectors themselves as 
possible. And now you're back to having a return line 
so you haven't really solved anything- you might as 
well be running efi. 
One thing that would be interesting though is to 
replace the CIS flapper door with a hot wire AMM. A 
unit that reads the AMM voltage and with one lookup 
table outputs a voltage to a proportional valve that 
varies the pressure just like the mechanical valve 
operated by the flapper door. This would allow you to 
use a huge AMM and eliminate the airflow limits many 
conventional cis distributors impose. But again, buy 
this time you could have converted to EFI so most of 
this is pretty moot imo. Now where did I put that 
medication?...

-Kenny
AKA Captain Bondo

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