Gerry Hess wrote:

This is an interesting but complex solution to a no return system, but if
you apply the KISS principal, here's a better way. (I've tried it)
 On Volkswagen rabbits and other skateboard class vehicles using the Bosch
fuel system, there is a little device called an accumulator, that works on
the same principal as a hydraulic accumulator, by having the pump charge it
up and push against a spring loaded piston.

So....... You set up your pumps in a dual configuration, (all Bosch pumps
have a check valve for oneway flow, so it doesn't matter which one you run
on) and feed the resulting pressure into the accumulator. The output from
this accumulator goes to the fuel rail. On the rail you have a small 12V
pressure switch. (older Pontiacs have a dual oil pressure switch - one that
goes on at 5psi and the other shuts off at 35psi. I used this set of
terminals to run the pump, with a bypass switch "fuel pump boost"
for starting and safety. Not needed for starting. As the engine runs the
pump kicks on and off as needed to recharge the accumulator which is about a
cup and a half capacity. Even if you hook up the return line to the suction
side of the pumps, there will be no flow unless the pressure in the rail
exceeds the pressure regulator setting which is set a few pounds higher then
the switch. Only on fuel boost setting does it bypass back to the input side
of the pump.
Now ....you could get fancy here and put in redundant pressure switches, but
I think one switch to control one pump is enough, as you have the backup
pump and switch, and you can get it all at the wrecking yard.

So the system picture is: dual redundant fuel pumps, dual KEFI
controllers, each of the pair supplying & controlling a fuel solenoid,
each solenoid's output combined and plumbed to a distribution block from
whence go the individual cylinder fuel lines and nozzles/orifices.
Voila, run them both actively in parallel during TOL, and you cannot
have a power loss.

I will need a sketch on this to visualize it. Latter.

Paul Lamar

 
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