Z-Driver Posted September 29, 2003 Share Posted September 29, 2003 I just got my engine and tranny in . Now I need to hook everything up. My carb is a road demon jr. 725 and there is only a fuel inlet. What do I do with the other two lines. I've heard two options: find a way use the other two(return and charcoal canister) and the other is to just cap them off. Would this build pressurein the gas tank? Thanks, I know this is very simple but this is my first project car and I am unsure of some stuff. Quote Link to comment Share on other sites More sharing options...
Guest Perry Posted September 29, 2003 Share Posted September 29, 2003 we need more info about the car and your fuel system. did you put in an electric pump of some sort? Quote Link to comment Share on other sites More sharing options...
Z-Driver Posted September 29, 2003 Author Share Posted September 29, 2003 I am in the process of installing a holley fuel pump. I will wire it like in the JTR manual and run all the fuel lines the same as stock. Mainly I wanted to know what to do with the hard lines; the Fuel return line and vent line that are in the engine bay. Quote Link to comment Share on other sites More sharing options...
Guest Perry Posted September 30, 2003 Share Posted September 30, 2003 I assume this means you don't want a charcoal canister for some reason. The return line can just be plugged in the engine bay or at the tank. the vent I am unsure about. you either need the vent line or a vented gas cap. I can't recall if the newer style gas caps are vented or not. Either way you need to allow for air getting in the tank as the fuel is sucked out. Presumably since I've never noticed an air filter in a gas cap they are non vented, and the intention is to pull air through the charcoal canister. if this is the case just put some sort of filter on the vent line and leave it open in the engine bay. I chose to mount a Charcoal can inside the fender, which was pretty easy, takes care of the filtering, and meets local inspection requirements. Check out the search for old discussions on fuel line size too. If you use the stock supply line it may be too small at low pressure to supply more than a couple hundred horses and also there are issues with accelerative loading putting more pressure on your rear mounted pump and causing a lean condition. check this stuff out to be safe. I used a 280Z electric pump feeding a return regulator (modified Datsun regulator) in the engine bay which then feeds a Holley non return regulator near the carb. A search will tell you the advantages/disadvantages of each setup. Perry Quote Link to comment Share on other sites More sharing options...
Guest Perry Posted September 30, 2003 Share Posted September 30, 2003 Oh yea... Don't forget a way to prime the fuel system. I forget if JTR mentioned this or not but if you run the float bowls in the carb dry you will not be able to start the car easily unless you have a button to cycle the fuel pump without oil pressure. otherwise you have to turn it over until it has oil pressure and fills the bowls enough to run. Easy to overcome in the garage but not easy if you run out of gas somewhere on the road. I mounted a button behind the passenger seat. Perry Quote Link to comment Share on other sites More sharing options...
baddriver Posted September 30, 2003 Share Posted September 30, 2003 There is an easy way to get the electric pump to operate when cranking, assuming you have a 240 or 260z. If you are using the existing wiring, just remove the 'crank' fuel-pump relay, connect the black and white wire to the green wire (these are the wires that the relay controls, basically eliminating the relay) The yellow wire has power when cranking. Connect a diode (Polarity!) to the yellow wire and then to the black/green wires you just connected (stripe on the black/green wire side.) There, now you have power when cranking. Don't forget the diode, or your car may crank itself. I just eliminated the mechanical pump on my Z and put in a full-time electric. Less than $30 at the farm/fleet store, and plenty of GPH. Quote Link to comment Share on other sites More sharing options...
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