wrcbonk Posted August 14, 2010 Share Posted August 14, 2010 Hey guys, I have been working on my fuel tank and fuel delivery system for my RB25 swap. I have a 1971 240. The stock fuel lines are a 5/16ths-inch pickup line and a 1/4-inch return. The two hard lines coming off my RB are 5/16ths. So I removed the 1/4-inch line from the car and will replace it with new 5/16ths solid line. As far as the tank goes I need to make up my mind on an external pump or internal pump. I want my car's fuel delivery system to mimic the system out of the doner skyline, which uses an in-tank setup. At this point I can still change and go external. That is my main question for you Hybridzers. We all have that buddy who is a professional mechanic. Mine likes in-tank pumps because he claims the fuel cools the pump and noise is reduced. The same guy had a 240 for while, but then sold it. He gave me his tank for free so I felt like I could take a chance trying to modify it while still having my tank in case things blew up. In order to keep things from blowing up literally the first thing I did was have the tank hottanked in muriatic acid. After that I painted it to keep the external corrosion down, then I used the Kreme product to coat the inside. I ordered the stock RB25 in-tank pump, a blind plate for access, some bulkhead fittings for the pickup and electrical, and finally a one way ball valve to resist starvation. The blind plate was a pain. I could not get anyone to sell me a nut ring so I had to make one myself. I used sheet metal and threaded inserts. It sucked, but it appears to work. Then came the fun part, cutting into the tank. Its pretty amazing what a guy can do with a cut off tool, a dremel, and a set of step bits. So I have two questions: 1) Am I just asking for trouble going with an in-tank setup or do you guys think this will work well? 2) How well do bulkhead fittings seal? Is there a sealer I should be using? Oh yeah, I plan to put a filter in the engine bay inline with a fuel pressure gage. I want to thank Monzter and 1-Tuff-Z for their posts on the subject. Bonk Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted August 14, 2010 Administrators Share Posted August 14, 2010 Not an answer to your questions, but I believe it's relevant to your concerns... Baffles. You need baffles. Search for swirl pot or surge tank and you'll figure it out from there. Quote Link to comment Share on other sites More sharing options...
5thgenluder Posted August 14, 2010 Share Posted August 14, 2010 I don't see anything wrong with an intank setup. My concern would also be baffles. I ran an intank setup on my 350z and it was nice and pretty quiet. I also had a swirl lot on that car. Without baffles you will want to make sure you never run less than about 1/4 tank. I went to autozone and they sell a tank repair kit. It's a 2 part sealer that works almost exactly like mighty putty. Quote Link to comment Share on other sites More sharing options...
wrcbonk Posted August 14, 2010 Author Share Posted August 14, 2010 5thgen, Ok good to know you used the tank repair material. The guy mentioned it at the parts store, but I wasn't that was what I wanted. Understood that with my homemade system I will have to be cautious with the fuel level. Bonk Quote Link to comment Share on other sites More sharing options...
wrcbonk Posted March 21, 2011 Author Share Posted March 21, 2011 I finally finished my intank fuel pump project. I canned the homemade nut ring to secure the access plate. I was able to find a local machinist who made me one for a reasonable price:) Hoping to mount my RB25 early in April. Bonk Quote Link to comment Share on other sites More sharing options...
wrcbonk Posted January 2, 2012 Author Share Posted January 2, 2012 Just wanted to update anyone that is thinking about an intank fuel pump. My car is now running with the setup shown above. The car is not yet on the road. I will update the performance once I have thrown the car through some hard cornering. Bonk Quote Link to comment Share on other sites More sharing options...
NewZed Posted January 2, 2012 Share Posted January 2, 2012 Did you add any baffles at all or a surge tank? Where did the pump end up in the tank, it looks like it's in different spots in your pictures? Isn't running lean on a turbo motor a big no-no? You could be risking engine damage accelerating out of a high G turn, with your RB25DET. The stock tanks and plumbing uncover the inlet at ~1/3 tank on a hard left, and they have at least a simple baffle inside. Should be interesting. Quote Link to comment Share on other sites More sharing options...
wrcbonk Posted July 30, 2012 Author Share Posted July 30, 2012 Yep, everbody was right, not enough baffling. I didn't destroy my engine (YET), but I have had several 'cut outs' or losses of fuel pressure. So now I am in the process of trying to decide which of the many options would work best: add baffling to existing tank, build up a whole new tank with baffles and stay internal pump or go with external surge tank and exterior pumps. Leaning towards surge tank and external pumps. I already plumbed a second new 5/16ths hard line underneath the car and I own a spare unmodified 240z gas tank. If I go external surge tank, can I get away with using the existing 1/4-inch return fitting on the tank???? Or do I have to modify the tank no matter what for EFI? I have decided that I think modifying gas tanks kind of sucks. I am going to do some research before asking dumb questions about whether I need multiple pumps and how I would control all that with my fuel pump relay and signal from the ECU. Hint Hint, if you already know please hit me with any advice here:) Thanks Bonk Quote Link to comment Share on other sites More sharing options...
Xnke Posted July 30, 2012 Share Posted July 30, 2012 I cut the bottom off an old oil pan and welded it onto the bottom of my tank, after removing the original tank drain plug, and drilling another hole near the back center of the new sump. I routed the new fuel pickup tube down into the sump, and the return line also returns directly to the sump. Might give you a few ideas. 1 Quote Link to comment Share on other sites More sharing options...
wrcbonk Posted February 22, 2013 Author Share Posted February 22, 2013 Guys, wanted to wrap this up. I went with an external system, http://forums.hybridz.org/topic/110485-bcbroncos-surge-tank-install-and-use/. If I come by an extra tank, I will consider separating the tank and trying an internal system again. My only issue with external is the noise of the pumps. But, it is nice to be able to fix anything that goes wrong and never think about the tank. Bonk Quote Link to comment Share on other sites More sharing options...
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