jacob80 Posted January 1, 2009 Share Posted January 1, 2009 Hey guys, I'm worried about the stock fuel lines that run the length of the body, the hardlines. Will these lines be fine as long as we have a surge tank setup in the engine bay? Thanks! Quote Link to comment Share on other sites More sharing options...
z-ya Posted January 1, 2009 Share Posted January 1, 2009 How about some more information? For starters, What Z do you have? Quote Link to comment Share on other sites More sharing options...
jacob80 Posted January 1, 2009 Author Share Posted January 1, 2009 How about some more information? For starters, What Z do you have? Yeah, true, sorry about that. It is a 1973 240z. It has the stock fuel lines in it. We are dropping a L28ET into it. My understanding was that it is ok to have these lines as long as you run a surge tank. Correct me if I'm wrong. Here is a picture: There are three lines total. If it is possible to use these stock lines, which ones do we use? I know one of them is really, really small. If not possible, what is another methos of delivering fuel? We are using the stock tank also. I'm assuming it will go like this: Tank>low pressure pump>stock hard lines>surge tank>high pressure pump>fuel rail>return line to tank Quote Link to comment Share on other sites More sharing options...
chrism Posted January 1, 2009 Share Posted January 1, 2009 I'm running stock fuel lines and my pressure is between 34psi and 50psi using a rising rate regulator. Most of the problems I was having were the connections using mechanical clamps. They need to be very tight to keep fuel from leaking around the regulator and filter. Other than that, I haven't had any problems. I run a fuel injected RB20DET. I have a 75 280z with the stock tank and return line. Quote Link to comment Share on other sites More sharing options...
jacob80 Posted January 1, 2009 Author Share Posted January 1, 2009 I'm running stock fuel lines and my pressure is between 34psi and 50psi using a rising rate regulator. Most of the problems I was having were the connections using mechanical clamps. They need to be very tight to keep fuel from leaking around the regulator and filter. Other than that, I haven't had any problems. I run a fuel injected RB20DET.I have a 75 280z with the stock tank and return line. Yes, but your car already came fuel injected, mine was carburated, and Im trying to understand what I need to do to successfully provide enough fuel to the engine without leaning it out due to my stock tank and possible too small of lines. Quote Link to comment Share on other sites More sharing options...
chrism Posted January 1, 2009 Share Posted January 1, 2009 Ya, I didn't see your reply in time. Guess I type to slow. Quote Link to comment Share on other sites More sharing options...
zzzzed Posted January 1, 2009 Share Posted January 1, 2009 yeh i am interested in this also Quote Link to comment Share on other sites More sharing options...
Nizm0Zed Posted January 1, 2009 Share Posted January 1, 2009 what size are your fuel lines? eg, if you were going to go buy some rubber hose, would you get 1/4 inch? 7/16ths? 5/8ths? 3/4 inch? efi will run on the smaller lines, but if you want the engine to make lots of power, eg big turbo, lots of boost. then you need fuel lines big enough to supply the fuel needed. generally, i would say 5/8ths minimum for efi. also, remember to change ALL of your rubber hose to EFI spec, and replace all of your hose clamps with screw type ones suitable for EFI use. Quote Link to comment Share on other sites More sharing options...
240z!!! Posted January 1, 2009 Share Posted January 1, 2009 Isn't it possible to run the stock 280z lines in a 240z....and if you get an early model gas tank out of a 280z i think 76 or 75 then you dont have to do the surge tank unless your running races.... Quote Link to comment Share on other sites More sharing options...
z-ya Posted January 1, 2009 Share Posted January 1, 2009 The 5/16" line is fine, but the 1/4" return is too small for EFI. You want zero pressure (flow only) behind the regulator, so that back pressure doesn't effect the high pressure side. I'm not sure about using a 280Z line, I think they are quite different. I know people that have use two stock 240Z 5/16" lines, one for a feed, the other as a return. You can also make new lines using 5/16" aluminum tubing (easy to bend). Don't run rubber lines under the car as they can be easily damaged by road debris. Pete Quote Link to comment Share on other sites More sharing options...
jacob80 Posted January 1, 2009 Author Share Posted January 1, 2009 The 5/16" line is fine, but the 1/4" return is too small for EFI. You want zero pressure (flow only) behind the regulator, so that back pressure doesn't effect the high pressure side. I'm not sure about using a 280Z line, I think they are quite different. I know people that have use two stock 240Z 5/16" lines, one for a feed, the other as a return. You can also make new lines using 5/16" aluminum tubing (easy to bend). Don't run rubber lines under the car as they can be easily damaged by road debris. Pete I believe two of the three lines are actually decent size. The only one that is too small is one of the two on the passenger side, and I belive that was for an evap system or something, I dont even know. But is there anyone out there that uses the stock 240z lines? Quote Link to comment Share on other sites More sharing options...
jacob80 Posted January 1, 2009 Author Share Posted January 1, 2009 Heres the surge tank setup we would like to run: Quote Link to comment Share on other sites More sharing options...
z-ya Posted January 2, 2009 Share Posted January 2, 2009 the stock 240Z return is 1/4", and is on the passenger side along with the feed. The other 5/16" line is on the driver side and goes to the top of the expansion tank above the gas filler. Whether you use a surge tank or not, you still need a return. In fact, you need two returns with a surge tank, one back to the main tank, and on one back to the surge tank from the regulator. Pete Quote Link to comment Share on other sites More sharing options...
jacob80 Posted January 2, 2009 Author Share Posted January 2, 2009 Yes, just as the picture states. So, as long as I use the two 5/16 lines I will be fine? And as far as a low pressure pump, we have one mounted in the rear of the car, should we have a second located by the surge tank as shown in the picture above? Quote Link to comment Share on other sites More sharing options...
Daeron Posted January 2, 2009 Share Posted January 2, 2009 the stock 240Z return is 1/4", and is on the passenger side along with the feed. The other 5/16" line is on the driver side and goes to the top of the expansion tank above the gas filler. Yes, just as the picture states. So, as long as I use the two 5/16 lines I will be fine? One of the 5/16" lines is the original feed line, which is fine. One of the 5/16" lines runs back to the expansion tank above the gas filler, NOT back to your gas tank, and really should NOT be used (in stock configuration) as a return, since it doesn't actually return to the gas tank. I am not certain how much work would be involved in MAKING the other 5/16" line go directly into the 240Z gas tank, but it does not go there as your car sits now; the 1/4" line that you had thought was evap or something is the return line into the tank. I would suggest finding the FSM for you r model year on xenons30.com and tracking down where what hoses and pipes go and investigating how hard re-routing the evap 5/16" line to use as a return. That, or simply buy some tubing and run new lines. It isn't the cheap solution, but it is NOT hard and it IS the best, most worry-free way. Quote Link to comment Share on other sites More sharing options...
Clifton Posted January 2, 2009 Share Posted January 2, 2009 On my 73' I originally used the stock feed line and the vapor or some other line for the return. It was a little larger than the actual return line. I ran it with a 255lph Walbro, made 500+rwhp and fuel pressure was good at idle. I later went to twin pumps and did both lines in 3/8 hard. Quote Link to comment Share on other sites More sharing options...
jacob80 Posted January 2, 2009 Author Share Posted January 2, 2009 Actually, when we got the car, there was no expansion tank. So we have both 5/16 lines running back to the tank, so it should be fine. The ideal thing to do would to be to put in an efi tank and 3/8 hard lines, but we actually just redid the stock tank (repainted and coated the inside), so its good to go. I think if we run the surge tank setup, we should be fine, dont you guys think? Quote Link to comment Share on other sites More sharing options...
z-ya Posted January 2, 2009 Share Posted January 2, 2009 If you are using it on the street, you don't really need a surge tank. Just keep more than 1/4 tank in there. If it get's below that it will suck air as the fuel sloshes around. If you have the surge tank and extra pump, might as well put it in while you at it. You can use a low pressure pup as the lift pump BTW. Quote Link to comment Share on other sites More sharing options...
24OZ Posted January 2, 2009 Share Posted January 2, 2009 I have a 73 240Z and did the same as Clifton, made the stock feed line as my return and ran a new wider diameter kunifer pipe as my feed line. I had the tank opened up and baffles were welded into the tank with a can welded in. Haven't tested it yet, but should work good. This is where I positioned my efi fuel pump and filter. If you use rubber lines to the pump like i have, make sure they are for use with EFI. Quote Link to comment Share on other sites More sharing options...
theghosttanker Posted January 2, 2009 Share Posted January 2, 2009 Some safety rules to remember, which some guys here are forgetting: Of course all rubber hoses and clamps must be able to handle EFI pressure, so all the rubber hoses and clamps on the 240 need to be replaced. When everything is working perfectly, it's true that there is very little pressure in the return hoses, but things don't always work perfectly. A defective pressure regulator can indeed pressurize your return lines, and this of course is a dangerous situation. Defective venting in the tank can also cause the fuel vapor in the tank to pressurize the tank and the return lines, again causing safety issues. The ENTIRE fuel system should be able to handle pump pressure, and rubber hoses should not run exposed in the bottom of the car. Quote Link to comment Share on other sites More sharing options...
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