I am the guy who built Ratzilla ,a 39 Chevy rat Pu with the 2.8 v6 located in the back of the cab . This is my 6th summer on the road . I lost my power to my fuel pump ( it is the stock Fiero pump grafted into a different tank and my hot wire comes thru the harness ) . I traced the dead power wire back to the harness , where it goes into the big fat factory ( slightly reworked for my application ) harness . Instead of opening up the harness to see where the loss of power problem is ( yes I checked all the fuses ) I am thinking of running the hot wire directly to the battery . There will be a separate toggle switch to turn the pump on , and an inline fuse ( 10 amp I believe ) . I don't know if there are any relays or connections to the computer that I will be by - passing and if this could cause me problems that I can't see right now . Any thoughts will be appreciated LFE PS I hot wired the pump and it came on and the engine started so I know it is the hot wire not the pump .
factory would have a relay that is turned on by the ECM. The backup power (if the relay fails) is from the oil pressure sender. It is a orange / black stripe wire (from 10A fuse in fuse block) to relay and Oil pressure sender, Tan / white stripe to pump from relay and Oil pressure sender. Dk Green / white stripe from ECM to relay for relay activation. If relay fails, oil pressure sender is the relay bypass to keep the fuel pump running. (it only will keep the fuel pump running if there is oil pressure).
Bypassing them with a switch removes the failsafe of accident (collision) fuel cut off, and forgetting to turn it off.
-Dave
[This message has been edited by IFLYR22 (edited 06-25-2012).]
Thanks for the reply , any thoughts on what might have happened to cause the hot wire to go dead . I started and drove the truck up and down my drive way on Wed and on thurs it would not work .
I don't know much about your setup, but have you checked the orange/black stripe wire at the relay or oil pressure sender for +12V? You can unplug the connector at the oil sender and use a meter/test light probe to see if the power is there. You don't need the key on for that. That would verify that the power to the relay/sender is good. At the relay, unplug the relay, put your meter/test light on the dark green/white wire and turn the key to on, not start. The meter/light should show power for 2 seconds (this the priming of the fuel system, and should be in sequence with the check engine light). That would verify the ECM working or not. If you have maintained a "stock" setup, a loose wire would the first thing I would look for, relay and oil pressure sender would be next, ECM would be last.
Also, check the ground (black wire)from the relay. It was under the relay on the firewall.
-Dave
[This message has been edited by IFLYR22 (edited 06-25-2012).]
