rchrd989 Posted February 23, 2007 Share Posted February 23, 2007 Im wondering how you guys have yoru fuel return set up. Im setting up a fuel cell in the rear of my Z with an electronic fuel pump right at the cell. Did stock Z's have a line that went all the way back to the tank or what? I tried doing a search on here but couldnt really find anything. When I got my Z the return line was pinched off. thanks Richard Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted February 23, 2007 Share Posted February 23, 2007 yeah, they had a return. A 5/16 supply and the next size smaller return. I will be running 3/8 supply and return with my V8 set up. Quote Link to comment Share on other sites More sharing options...
rchrd989 Posted February 23, 2007 Author Share Posted February 23, 2007 do you run the return all the way back to the tank? And if so is there a factory hard line underneath? Quote Link to comment Share on other sites More sharing options...
wheelman Posted February 23, 2007 Share Posted February 23, 2007 There should be a 1/4" hard line for vapor control that goes back to the tank. What are you planning to do? Depending on how much HP you plan to make you might want to replace the feed line with 3/8" and use the 5/16" as your return. I replaced both with 3/8", but I'm running an LT1 and the tank is from a 2001 Camaro. Wheelman Quote Link to comment Share on other sites More sharing options...
rchrd989 Posted February 23, 2007 Author Share Posted February 23, 2007 I'm setting up a L28 with 30 over deck flush flat tops. On top of that I have a E88 with a 3 angle valve job with a stock cam. Im then setting up my 72 SU's with SM needles. So im not sure on how much power Ill be having, but not too much. Quote Link to comment Share on other sites More sharing options...
DREW RBZ Posted February 23, 2007 Share Posted February 23, 2007 Wheelman has the proper suggestion. For your application use the feed as your return then plumb in a new feed line in 3/8" and you will have more than enough fuel for your application. Quote Link to comment Share on other sites More sharing options...
X64v Posted February 23, 2007 Share Posted February 23, 2007 If you're just going to be running su's on an l28, the stock feed is just fine. If you're using the stock fuel rail, then the stock return is alright as well. If you're not, you can run the return through a fuel pressure regulator and then into the 1/4" vapor line. All assuming this is a 240z. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 23, 2007 Share Posted February 23, 2007 When I was running SU's I just dead headed the fuel line at the carbs and didn't run a return line at all. I switched because I figured out it was the stock fuel rail and the mechanical pump that was causing the gas to boil. Both would get too hot to touch on a hot day. I ran a rubber hose from the fuel filter across the radiator core support and then back to the SU's. I can't remember the specifics, but there was a Y that split it from the main feed line to each of the carbs. That was it. It was really simple. I didn't even remove the return line, I just clamped a small bolt in the rubber hose on the end after I realized that gas was coming out under hard braking. The downside to not running a return line is that it is harder on the pump. If you do decide to run a return just realize that the restricted orifice in the stock fuel rail is the pressure regulator. So by changing the size of the hole you'll change the fuel pressure to the carbs. You'll probably have to mess around with the hole size before you get it dialed in. If you dead head it then you just use a regulator in the feed line and that's it. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted February 23, 2007 Share Posted February 23, 2007 do you run the return all the way back to the tank? And if so is there a factory hard line underneath? The factory return runs all the way back to the tank. There are two penetrations in the tank, the 5/16 supply and 1/4 return. Each has it's own hard line with a short section of rubber hose connecting the tank to the hard lines. Both tank penetrations are right next to each other. There is also a third 1/4 inch line that is a tank vent. On my California edition 70 model it goes from a vapor recovery tank in the right rear C pillar up to the crankcase/intake manifold. Are you sure this isn't the line that was pinched off? I completely removed that line from my car. Quote Link to comment Share on other sites More sharing options...
rchrd989 Posted February 23, 2007 Author Share Posted February 23, 2007 the line that was pinched off was the return on the fuel rail. hey i really appriciate all of the responses! thanks, Richard keep them commin! Quote Link to comment Share on other sites More sharing options...
24OZ Posted March 5, 2007 Share Posted March 5, 2007 I've been reading this thread with great interest. I have a 240Z but I am running EFI with an L28ET engine, I plan on developing 280-300 hp at the wheels. Would the stock return line work or shall I as suggested, make the stock fuel supply line (5/16") into my return line and run a new pipe 3/8" as my supply line. Thanks guys. Quote Link to comment Share on other sites More sharing options...
ktm Posted March 5, 2007 Share Posted March 5, 2007 The stock return will not work. If you use the stock return, chances are your fuel pressure will be high. Most folks use the stock feed line as the new return and plumb a new 3/8" feed. Another thing you can do (I am going this route myself) is to run a surge tank. You can use a low pressure carbed pump to feed the surge tank using the existing feed line. The return line from the surge tank to the gas tank can remain the same size as well. From the surge tank to the engine, you run a larger feed and return line as well as an EFI pump. The surge tank's primary purpose is to keep from leaning out under hard acceleration and cornering. Quote Link to comment Share on other sites More sharing options...
24OZ Posted March 5, 2007 Share Posted March 5, 2007 Thank you for the reply. I have looked closely at this option but I am not 100% happy having fuel in a large canister in the engine bay or at the rear of the car. If its the only option then so be it, but at the moment I am researching to see if its possible to just put in baffles in the existing tank and avoid surge tanks altogether. Quote Link to comment Share on other sites More sharing options...
wheelman Posted March 5, 2007 Share Posted March 5, 2007 240Z, It's possible to add baffles and/or a sump to the stock 240 tank. I initially elected to add a sump and ran it for about 3 months but then the tank started shedding rust real bad and plugged several filters. To avoid having to swap filters every other week I decided to install a tank from a 2001 Camaro. They're plastic and have a built in pump and swirl pot that eliminates problems with starvation. The only draw back (if you consider it a drawback) is you have to remove the spare tire well. There are a couple threads on here that show pictures of this swap if you're interested. Wheelman Quote Link to comment Share on other sites More sharing options...
ktm Posted March 5, 2007 Share Posted March 5, 2007 You can have a sump welded onto the bottom of the 240z fuel tank. While not as effective as baffling the tank, it is still better than a stock 240z fuel tank. A final option is to track down a tank from a 1975 or 1976 280z. These gas tanks are a bolt-on swap with our 240zs and are already baffled. Later model tanks will not fit. Quote Link to comment Share on other sites More sharing options...
24OZ Posted March 5, 2007 Share Posted March 5, 2007 Thank you guys, for the very helpful remarks. Wheelman, I can see that being a great option for many, I'd like to keep the wheel well though. I may see if its possible to have the tank cut open from below and having baffles welded in with no sump installed. Quote Link to comment Share on other sites More sharing options...
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