Guest bluex_v1 Posted October 16, 2002 Share Posted October 16, 2002 I'm trying to do an econo efi swap in an early 260z...right now at least one of my vent lines is leaking bad when the tank is filled, so I'm considering what mods I should do to resolve that problem and set it up for future efi if I can while I'm at it. I've not found a firm consensus of whether or not all the evaporative vent stuff is requried. I don't have to worry about smog inspections, so what is the bare minimum I need as far as evap equip? I REALLY don't like having any vent/evap stuff in the cabin area. Can I just run a looped hose from the lower level vent fitting up to one of the upper level ones and then T the remaining upper vent hose into the filler neck or something similar and eliminate the interior hoses, condensor tank, and charcoal canister and get a gas cap that has a pressure release valve on it or something? Also would the stock output and return fittings on an early 260z be enough to support a stock efi 5.0L v8? (19lb sequential injectors) What works? Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted October 17, 2002 Share Posted October 17, 2002 Whatever you do don't use heater hose. It won't hold up to the gas for long. The Nissan hoses are expensive but probably your best bet for curing the problem. I have read previous posts from guys who have capped off the vent lines. You have to have some type of vent, but I would think it could be much less elaborate than all the hoses the stock Z uses. Quote Link to comment Share on other sites More sharing options...
z-ya Posted October 17, 2002 Share Posted October 17, 2002 From what I've heard, if you plug up all the vent lines and remove the expansion tank, you willnot be able to fill it all the way. I bought some 10AN fuel line from Summit or Baker Precision, as it was a lot cheaper than the stock one. I would drop the tank, you may just need to tighten up some clamps to fix the problem. Pete Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted October 17, 2002 Share Posted October 17, 2002 I got rid of all the vent hoses and vent tank. Check out this old post: http://www.hybridz.org/ubb/ultimatebb.php?ubb=get_topic;f=13;t=000301#000000 Quote Link to comment Share on other sites More sharing options...
Guest bluex_v1 Posted October 17, 2002 Share Posted October 17, 2002 Mike, I read that, but I guess I misunderstood something...so the remaining top vent line, did you route that to the small tube that runs up to the charcoal canister then, or is it just forming a loop and going directly back into the main tank via the inlet for the evap tank's drainback? I think I'd be doing more or less the same thing, except instead of welding the two shut, I'd just run hose from the lower one to the rearward upper one, forming a loop. Then the remaining upper/forward vent line, I would run into the fill neck, I guess cap the evap tank drain-back and I suppose do the same with the drilled gas cap. (How bad is this environmentally though? having it evap direct to the air...and over the course of it sitting for a week, how much gas am I going to lose from my tank? -I'm guessing its pretty insignificant... man this stuff is confusing...I need my service manual diagram ...but the other question remains...would the stock out/return lines for the tank be adequate for a 250 HP 5.0? I know you went with the welded sump, which is smarter, but also another $100 or more after I get the tank boiled out, stainless lines for protection down low, and all that. Did you put the sump in because you *needed* it, or just because it is better? Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted October 17, 2002 Share Posted October 17, 2002 I didn't do what your first paragragh said, but did the second paragragh, except I welded the two holes that you are going to loop. I am not using the stock evap tank. The forward hole in the tank has a hose that runs to the filler neck hole that used to connect to the evap tank. I'm not worried about evaporation, but I'm sure it's very little. I'm not sure if the stock out/return lines are adequate, but with EFI and a stock tank if you go below half full around corners you loose fuel pressure because the baffles in the tank suck. That is why I added the sump, to make sure I always have fuel pressure. Another way to do it is build and install a surge tank, like this post: http://www.hybridz.org/ubb/ultimatebb.php?ubb=get_topic;f=20;t=000234 Quote Link to comment Share on other sites More sharing options...
Guest bluex_v1 Posted October 17, 2002 Share Posted October 17, 2002 Ok, I got it now. I don't want to mess with a surge tank though (want to keep everything clean and simple as much as I can), so the sump with a couple holes in the bottom of the tank is the way to go for me I think. now question #2337295: why did you position your sump so the fittings were facing toward the back? I guess under acceleration, if it were facing forward, it would slosh up the 'ramp' and starve? -but if you just cut a couple small holes in the bottom of the tank right up front by the in/out, would it probably hold enough fuel in the sump to keep the pressure up? Option two could be ...put some vertical walls on the sump unit to extend up into the tank with a few holes drilled through the ones on the sides or front toward the bottom of the tank so I wouldn't have it slosh out toward the rear going uphill or under acceleration. I'm kinda concerned about the ground clearance with having the sump in/out facing toward the rear, and I'd feel safer if the fittings were further toward the front and facing forward so the sump would be better protected from speed bumps and stuff being tucked closer under the wheels. Quote Link to comment Share on other sites More sharing options...
Mike kZ Posted October 17, 2002 Share Posted October 17, 2002 To answer question #2337295 I was concerned about ground clearance too, but have not had a problem. The only thing that is still on my mind is if, with slicks, I manage to lift the front wheels, I may scrape the sump, and boom! But I think I would have to be pretty high on the front end to do that, probably wont happen. Plus it gives a pro street look to the rear end! I think your first option would work, if you want to reverse the sump. I drilled 5 2" holes per instructions to the bottom of my tank. If you just drill two near the in/out holes I think that should work. Quote Link to comment Share on other sites More sharing options...
Guest bluex_v1 Posted October 18, 2002 Share Posted October 18, 2002 The instructions said 5 2" holes ?!? wow..so about 15 square inches of area for fuel flow into the sump right? That does seem excessive. I checked the summit site, but the sump there doesn't have any dimensions in the info. from looking at the "3/8" fitting bungs, I'm guessing its about 5"x8" where it attaches to the tank..is that correct? so I could just cut a 5"x3" slot over where the in/out will be, but do you think I'd be safe with say, 4.5"x2" (--equivalent to almost 3 2" holes- that way there would be a little lip out from each side to help with cornering g's and it would have an extra inch toward the back to hold in fuel under accel. ..which becomes increasingly important as the sump depth (fuel volume) becomes greater the further forward it is held in from. ..umm, did all that make sense? -surfing HybridZ during a training class at work Quote Link to comment Share on other sites More sharing options...
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