Hello there! So I think something's up with the fuel pump circuit on the RX7 FC I just bought. It seems like the pump doesn't activate when I turn the ignition unless I have the pump check connectors bridged. When the key is turned to the on position without the connector bridged the pump doesn't seem to pulse and no fuel shoots out of the secondary injectors. If I bridge it it begins pumping and I get a constant spray from my secondary injectors. What's up with this and what should be happening when I turn the key?

 

Welcome.
From a thread just below this one. Post #4 —-> https://www.rx7club.com/new-member-r...-pump-1149584/

 

Thank you Sgtblue
"The pump is only powered when the engine is cranking or running, via a switch in the AFM detecting airflow or the ECU detecting a crank."
I feel like I'm misunderstanding something very basic here. When I turn the key the engine turns over but no pump..... I remember reading that the AFM needs to detect airflow for the pump to turn on. The AFM works off of a metal flap attatched to a potentiometer in the air intake right? So this means when I turn the key my engine should turn over, start sucking air through the intake, open this flap, thereby turning on the pump? So if I start cranking and I get no pump then either this flap is not opening or there is something wrong with the AFM circuit? Sorry if this is very basic.

 

I meant to say when the key is turned to the start position i.e. when it is actually cranking I'm not seeing the pump work unless the check connector is jumpered. Theoretically if I have someone hold open the AFM flap while I crank the engine I should find the pump working correct?

 

If you are not getting the fuel pump during cranking, then off hand here are several things to check:

1. Is the ECU receiving the crank signal? Check wiring diagram in FSM for crank signal line to ECU. I think it's a blue wire, from memory.

2. Is the ECU receiving power? Check EGI fuse, and 12V connectors at coils (see FSM wiring diagram) to confirm ECU has power.

3. Is the ECU operating? Check for spark to confirm ECU is running.

Not sure why you are expecting fuel to come from the secondary injectors. They do not fire except over 3800 RPM and loads higher than 2" vacuum.