Does anybody know what generates the signal for the fuel pump to run?

I am having this problem with no power to my fuel pump. relay works,

voltage exists at oil pressure switch

ECM is new

relay has been changed

What ever tells pump to cycle and charge system at key on is not happening need to know what creates that signal.

thx


jeff

 

The ECM itself operates the pump relay for a two-second prime cycle at initial power-up. The ECM will run the two second pump cycle whenever the ignition has been off for at least 20 seconds, or whenever the ECM detects distributor reference pulses.

 

Thanks Vader... I am getting closer but still have an issue.

I cut the wire feeding my fuel pump a few inches past the fire wall near the computer. I am now getting my 2 second prime voltage!

but... the pump will not run during that prime cycle when I ran a jumper from where I cut the feed wire to the pump quick connect in the rear of my car. and...when I connect my bat charger in 2 amp mode to the pump terminals I hear it running in the tank but is still not building pressure at the gage on my shrader valve stem.

anyone have any suggestions now? resistance? why?


thx


jeff

 

Try powering the pump directly from a fully charged battery. The pump will likely draw 10-15A at full pressure. The battery charger on a 2A setting may not be able to provide adequate voltage and current.

 

O.K. I will try that right now.. my charger has a 12 amp setting. I will let you know how I make out.

thx

jeff

 

O.K. more progress but......

I put my charger on 75 amp mode and ran for 10 seconds. Got 15 pounds of pressure. Should get like 50 in that time period. Maybe I need to put more fuel in the tank? it shows 1\4 tank but the pick up might be sucking air?

Now I have to figure why it wont operate on the 12 volts supplied via ECM command.

thanks for your advice Vader.


Jeff