240z73dats Posted February 2, 2012 Share Posted February 2, 2012 hi i am new to this forum and well i singed up cuz i need help! i have a 240 with original fule lines. i am running a L28 block with a bored and polished p90 head which was carbed but i just installed a non egr fule ingetion system which has i beleive 38mm fule injectors and 50 mm. throttle body (webber throttle body)... (i payed 500 for everything with instalation) the guy who installed it kinda just slapped it on. he mentioned the fule lines needed to be swapped to the bigger 280 fule lines which i have but kinda dont wanna spend the money to install since i rebuilt the suspencion completely... so is this a MUST for me to install the fule lines? what will happen if i dont? can i get away with the stock fule lines? Quote Link to comment Share on other sites More sharing options...
NewZed Posted February 3, 2012 Share Posted February 3, 2012 What might happen - your high pressure/high volume EFI fuel pump will pump more fuel than the return line can handle and your fuel pressure will be too high and uncontrollable. Measure the fuel pressure with the new pump running, at the fuel rail. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 3, 2012 Share Posted February 3, 2012 Agreed. I ran 325hp through the stock feed and a -4 return line without a problem. The return line might be the issue. I seem to recall that Nissan had a built in restrictor in one end of the return hard line (it was swagged over to a .032" pin hole IIRC). Quote Link to comment Share on other sites More sharing options...
logr Posted February 3, 2012 Share Posted February 3, 2012 I Y'd the return line from the engine to both the chassis return line and the smaller line. It has worked fine for 2 years and an SR. Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted February 3, 2012 Share Posted February 3, 2012 When I installed my EFI (not factory Nissan set-up), I installed a 3/8" feed line and used the original 8mm feed line as my return. It has been working great this way for about 3 years. Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 3, 2012 Share Posted February 3, 2012 (edited) I used the factory Vapor Vent from the tank as my return line, and vented another 1/4 line on the tank to atmosphere out back and that has worked flawlessly since 1985... It runs on the left fender well to the emissions diverted valve. You can hook the stock FPR return directly to it, back to the tank. Don't know how many L28ET's I installed like that! Edited February 3, 2012 by Tony D Quote Link to comment Share on other sites More sharing options...
240z73dats Posted February 3, 2012 Author Share Posted February 3, 2012 I was thinking of wideing the ends even having a profecional cut it adn adapt a bigger line were possible. now i dont want to cut corners and kinda want to do it right ive invested 2 years and 5gs and no were near done or even looking perfect!lol but its a passion right!??? i still neeed to install coil overs or shocks not sure but should i just pay the extra cash and have the bigger return line and fule line installed?... sorry for this question maybe should of mentioned it or could be a totaly seperate issue.... well right before i did the swap the car was backfiring pretty bad... it doesnt only when i let off the peddle and coming to a stop. if im pressing the gas peddle it sound fine its when i left off the peddle that it back fires. the exhaust is custome made and have glass packs in the middle and was told by the guy who installed them that its becuaseof that i hear a back fire... ur help is very appreciated and i am welcome thank u guys Quote Link to comment Share on other sites More sharing options...
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