RE: spitting carbs/Holley fuel pump setup

["Jim Adney" <jadney@vwtype3.org>]

> > Why the oil pressure switch?  Well, in the instructions it gives a simple
> > wiring
> > schematic on how to power the fuel pump.  Part of the setup is using an oil
> > pressure switch that has a Normally Open and a Normally Closed lead and a
> > Common
> > lead.  The pump gets electricity from the starter switch lead when you crank
> > the
> > engine and once oil pressure is up the oil pressure switch closes (by now
> > the
> > engine is running and the key is in the normal "on" position) and now
> > electricity goes through the switch to the fuel pump.  Should the engine die
> > the
> > oil pressure will cease to exist, the switch will then open, and power will
> > be
> > cut off to the fuel pump.  So in an accident you don't have to worry about
> > fuel
> > being pumped into a potential fire situation.  Pretty neat, huh?
> 
> Sounds neat, but have you tried disconnecting the pump wire with the 
> engine idling to see how long the engine will idle on the gas in the 
> float bowl?  My guess is that you will be surprised at how long it 
> will go.

Oops, in the light of day I realized that my comment made no sense 
here since the question involves an engine which has already quit.

> Please run the test and let us know.  I'm really interested since I 
> have done this with FI and found that it is the better part of a 
> minute.  I'll try to remember to do this tomorrow.  I'll actually 
> time it this time.

Just out of curiosity I ran my test again and found that the engine 
stopped in about 3 seconds on the 73 and 10 seconds on the 72.  This 
is much shorter than I remembered, but the other time I did this I 
tried to see how long I could keep it going by pumping the throttle.

I wonder why my two cars are so different, but it may just be that 
the 73 hoses are older and stiffer and don't help support the 
pressure as longer as the newer 72 hoses.  Or I might have some kind 
of leak in the pump of the 73.

If anyone else wants to try this, just start your engine, then pull 
off the the white plastic plug on the fuel pump relay just in front 
of the fuse box.

Jim
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Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
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