zmaster Posted March 7, 2008 Share Posted March 7, 2008 does anyone know how to wire a relay for the fuel pump to make it turn off and on like it should normally??? Quote Link to comment Share on other sites More sharing options...
ArnZ Posted March 7, 2008 Share Posted March 7, 2008 What kind of car? Original relay? Are you bypassing the factory harness? Quote Link to comment Share on other sites More sharing options...
chrism Posted March 8, 2008 Share Posted March 8, 2008 Most relays will have a diagram on the cover. Quote Link to comment Share on other sites More sharing options...
jimzdat Posted March 8, 2008 Share Posted March 8, 2008 Try this diagram (designed for basic "Bosch" style relays--the square ones most commonly available) Just substitute "Fuel pump" for "Horns" Quote Link to comment Share on other sites More sharing options...
zmaster Posted March 8, 2008 Author Share Posted March 8, 2008 I want to bypass the original harness for my fuel pump to make it turn off and on like it normally should...it is on my 1975 280z coupe. will the relay turn the fuel pump on and off like it should. this is going to be my second to last atempt will be to buy a stand alone fuel management system. Quote Link to comment Share on other sites More sharing options...
jimzdat Posted March 8, 2008 Share Posted March 8, 2008 Basically all you will need to do (on the above diagram) is connect terminal 87 to the fuel pump hot wire, and 86 will be "ignition hot"--that will cause your pump to run whenever the key is on. That said, it will actually be overriding a safety feature--many people will install a "snap switch" in the circuit that needs to see positive oil pressure to complete the circuit--that way if engine dies, no more fuel pumping out. IIRC, the original AFM has a small switch inside that keeps the fuel pump from running unless there is flow going through it--if you manually open the flapper, it will complete the circuit Quote Link to comment Share on other sites More sharing options...
zmaster Posted March 9, 2008 Author Share Posted March 9, 2008 i have done that test, and it doesn't work. I have two GOOD afms sitting in my garage including the one on the car. if a lower voltage would go to the fuel pump then i would probably be able to keep a constant flow but not too high of a pressure. Quote Link to comment Share on other sites More sharing options...
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