EMWHYR0HEN Posted February 1, 2006 Share Posted February 1, 2006 I have a 71' 240Z and just swapped a RB25DE. AS of right now, im using a Walbro 255LPH external inline pump. My problem is that im using the stock hardlines and if you recall the return line for the 240Z is tiny. There is just too much pressure on the ruturn. As a result, My fuel pressure going into my engine is way too high, causing an unstable idle, and poor throttle response (my guess is that its messing up my Air/Fuel Ratio) So... What are my options with out putting in a fuel cell? i really dont want to hack my car up. I could just put a thicker return line but the inlet on the gas tank for the return is still small. anyone actually tap a bigger whole in their tank? options? anyone? Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted February 2, 2006 Share Posted February 2, 2006 Are you sure that is the problem? Have you measured the pressure in the return line? Checked that its not blocked? Checked that your FPR is working correctly? I ran another -8 (1/2") line in speedflow pipe for my car and used the stock feed as the return. Bit of work, but I don't have to worry about it now. Dave Quote Link to comment Share on other sites More sharing options...
240Z_Master Posted February 2, 2006 Share Posted February 2, 2006 Well, the return fuel pressure shouldn't even exist. Is the regulator doing it's job? Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted February 2, 2006 Author Share Posted February 2, 2006 No, the return line is not blocked, i can hear the fuel squirting back into the tank at a very high rate. I checked my FPR, its working fine. Heres what i did to make sure that this was my problem: I put my return line directly into a gas canister and ran the engine. There was no pressure on the return line and it ran perfect. ilde was good, and throttle response was instant. Also, I was told if you add resistance to the return line your FP will increase, which is exactly my problem. Im thinking of getting an external FPR with a gauge (maybe B&M?) for now. but ultimatly i' d like to fix the problem from the source and not just go around it. How hard do you think it would be to cut a hole into the tank and tapping or welding a 3/8'' fitting to it? Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted February 2, 2006 Author Share Posted February 2, 2006 another question for you 280Z/zx guys, did those modles come with bigger fittings on the gas tank? Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted February 2, 2006 Share Posted February 2, 2006 My zed has three lines that run down the car. One big thats originally for fuel feed, and two small ones. If yours has this maybe you could use both small ones for fuel return? Dave Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted February 2, 2006 Author Share Posted February 2, 2006 Thanks, Dave. That made me think, I know there is a bigger line that is used for a fuel tank vent, I think? it runs down from the tank onto the firewall and onto the driver side of the engine bay. would it be possible to use that for a return and i guess block the vent? haha that doesnt sound like a good idea. anyway, what do you think? possible? Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted February 2, 2006 Share Posted February 2, 2006 Thats the one I was talking about I think. I'd say you could work something out, but I'm not sure where it goes or what to do with the vent. If its bigger on your car maybe you could swap them over so the bigger line is used for fuel return? Dave Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted February 2, 2006 Author Share Posted February 2, 2006 I guess its worth a try. I'll take a look at it and see where it goes. hope nothing blows up on me. well if it does work, thanks for mentioning it, Dave Quote Link to comment Share on other sites More sharing options...
Ed260Z Posted February 2, 2006 Share Posted February 2, 2006 If it ran fine with the return line in a catch can, then I would say that you have a vapor vent issue. It sounds like your tank is under pressure when your running. There are 4 vent lines on the tank, and if they're the original I'm sure they're shot. I've seen a few of the lines on Ebay, and MSA also has them. Quote Link to comment Share on other sites More sharing options...
240Z_Master Posted February 2, 2006 Share Posted February 2, 2006 I would like have some kind of return to a surge tank, that might help out with fuel sloshing, and allow fuel to flow back to the surge tank in a larger open area then the tiny vents of the stock gas tank. Quote Link to comment Share on other sites More sharing options...
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