[Supras] Fuel pump system priming and pump resistor

[Hacker J]

Bernie,


The fuel pump is activated by the so-called "circuit opening relay". The relay has two coils. One coil is energized by the crank (STA) signal in both
N/A and turbo cars. After engine starts the second coil is kept
energized by a switch in the AFM if a N/A car or by the ECU if a turbo.  For the turbo, the relay is connected to the FC output of the ECU.  I haven't got a definitive answer on what is used to enable FC, but it is most likely some minimum frequency from the AFM that indicates flow and hence a running engine.

Jon

----- Original Message ----

When pulling the engine out of my '91 turbo, I happened to turn on the 
ignition switch and the fuel pump ran, flooding the floor with fuel.  
Now with the new engine in place (also have Walbro pump in tank) that 
does not happen.  Every other FI car I've had has a "prime" mode where 
the pump will run for a few seconds with the ignition on but not in the 
start position.  Shorting +B and FP in the diagnostic connector does run 
the pump, so the Walbro installation is OK.  There is voltage to the 
pump when running the starter (measured at the FP connection.  Tank is 
empty for the moment so I can't run the pump for too long.  Still need 
to get upper intake, fuel rail and intercooler piping in place. 


Also:  What is the recommendation about the fuel pump resistor with the 
Walbro pump?  Should it be removed or replaced with a resistor of lower 
resistance?


Thanks, as always.


BernieK. 


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