[alfa] RE: Low Spica Fuel Pressure - Followup

["Jack Smith" <roadtrip999@xxxxxxxxxxx>]

1. If the supply pump is the old style SPICA/Bosch I wouldn't automatically 
discount a failing pump. What I would do If I were you, is get a 0-20lb fuel 
pressure gauge and make a "T" adapter so you can measure the fuel pressure 
between the front filter and the injection pump. It should be  15-18 psi.

The supply pump off the L-Jet cars works fine, but you do have to narrow the 
restrictor to 1/16" by soldering in and redrilling. The reason this must be 
done is that the L-Jet supply pump does not discharge the flow rate/volumn 
that the old style pumps did. The slightly smaller restrictor boosts the 
pressure back up to 15-18, from about 10 psi if it's installed without the 
restrictor mod. It still provides  sufficient cooling to the injection pump.

Engine temp will have little to do with the performance of the injection 
system. Hot roads, exhaust pipe near the gas tank, etc, can heat the fuel in 
the tank up to close to boiling and send the supply pump into vapor lock. 
Low fuel levels obvioulsy make it that much worse. Engine temp won't matter 
too much.

A Leaking PRV is a long shot but should be checked anyway. Another scenario 
that could cause stalling after a freeway run could be that the return line 
is plugged at the tank return inlet. This would cause deadheading in the 
pump, hot fuel, and eventual caviatation and loss of pressure. At higher 
engine speeds it may run fine because  you're using fuel at a much higher 
rate and the pressure doesn't increase that much. If the car's been sitting 
for a long time, varnish could form at the top of the fuel level in the tank 
and clog the return line.

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