urbancustomz280z Posted September 22, 2013 Share Posted September 22, 2013 hey guys i just got a 1975 280z not to long ago the car came with pretty much everything i need aka the wiring harnesses and so on. now i just started to wire it all back up and all is going well learning alot but i cant get the fuel pump to cycle on at all. so i go look at it and it for sure is aftermarket and the guy ran a power wire straight from the fuel pump to the engine bay. now my question is how do i go about either wiring it up to the factory harness. or can i just wire it to a switch and flip it on when i need it then in that case will it always run will i need a pressure switch to cut it off when i reach the 36 psi of fuel pressure? help is much appreciated thanks guys. Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 23, 2013 Share Posted September 23, 2013 (edited) There's a switch in the AFM and a relay that would be used to get back to factory set-up. See the wiring diagrams and descriptions in the Engine Fuel, and Body Electrical, chapters - http://www.nicoclub.com/FSM/ Since you're asking about a "pressure switch" to control fuel pressure I'll say that you should read all of the Engine Fuel chapter, before you do any work on the engine and it's fuel management system. Things will make more sense with the basics in the back of your mind while you're working. Edited September 23, 2013 by NewZed Quote Link to comment Share on other sites More sharing options...
urbancustomz280z Posted September 23, 2013 Author Share Posted September 23, 2013 thanks very much for the reply and the diagrams they are very help full. let me ask you this i can take the power from the pump and run it in with the relay and that should fix the issue correct? ive been looking through all of these diagrams for weeks now now trying to understand them and it is not easy but im able to follow most of it. Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 23, 2013 Share Posted September 23, 2013 The fuel pump relay should be right above the handle for opening the hood, inside the cabin. It even looks like the drawing. Check to see if the original wires to power the fuel pump are still there by the pump. If so, it should be pretty easy to figure out if they can be re-connected. It may be also that everything is already connected correctly and you don't know how to cycle the pump power. Either disconnect the small wire at the starter solenoid and turn the key to Start, or turn the key to On/Run and rotate the AFM vane. Both of these actions should provide power to the pump. If you don't hear the pump it may not be a power problem, just a stuck pump. Use a meter to verify. Quote Link to comment Share on other sites More sharing options...
urbancustomz280z Posted September 23, 2013 Author Share Posted September 23, 2013 ok i know ive got the relay there are two plugs that go into it. i know the pump work cause i have put it to power and it send fuel to the rail. the pump that is in the car looks nothing like the factory pump it is a cube pretty much kinda confused me for a little till i saw the power wire going to it. but i also saw two other wires that were not connected to anything im guessing those are the original fuel pump wires? if so that should mean i can take the power from the pump and connect it to the wire coming from the relay/afm switch and that should cycle the pump? Quote Link to comment Share on other sites More sharing options...
urbancustomz280z Posted September 23, 2013 Author Share Posted September 23, 2013 ok upon further investigation i figured out that the pump i have is a 20 dollar ebay pump that is used for carburated engines so it will only run a max fuel pressure of 7psi not the 38psi i need lol so i am going to order me a walbro 255lph esternal inline pump and then wire it up correctly unlike the current pump. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted September 23, 2013 Share Posted September 23, 2013 ok upon further investigation i figured out that the pump i have is a 20 dollar ebay pump that is used for carburated engines so it will only run a max fuel pressure of 7psi not the 38psi i need lol so i am going to order me a walbro 255lph esternal inline pump and then wire it up correctly unlike the current pump. That should take care of it. Quote Link to comment Share on other sites More sharing options...
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