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brianstj

Fuel Plumbing

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Well, since no one chimed in on their own experiences running braided fuel lines with AN fittings in their car, I had to go and figure everything out for myself :)

At the tank, I bought a -6 steel fitting that was meant to screw in to pipe threads on the other end. I machined off the threads and drilled out the remaining pipe thread portion to fit the fuel sender tube. Then for a whopping $6, my local welding shop TIG welded it on for me.

I ran the -6 braided line under the trunk panels to the left side of the car, and then up and through the rear seat panel in to the car. I had to test fit the seat and play around a bit to make sure it would not squish my fuel line when installed. From there it was in to the electric fuel pump mounted on the vertical panel that the front edge of the rear seat rests on - This seemed like the lowest elevation I could get for the pump while not exposing it to any road hazards.

The fuel pump was wired up with a relay. I had done a battery relocation with the E30 battery cable some time ago, and I finally found a good use for the smaller gauge wire that parallels the big one - I used it to feed power to the fuel pump relay. I threw in an inline fuse holder between the relay and pump, and wired up a key-on power wire (through a "safety" switch under the dash) to turn the pump on with the car.

Getting back to the plumbing, I ran -6 line off the pump and popped a hole through the floor under the rear seat to run the line on the under side of the car. I used rubber insulated clamps to secure the line a little ways up in to the drive shaft tunnel. Clearance was pretty goot, but the fuel line came about 2" from the exhaust at one point. I put a lenght of rubber hose around the braided line where it was closest to the exhaust.and wrapped that in aluminum tape hoping to insulate/reflect some of the heat - we'll see how that goes.

Snaking the -6 line around the pedal box, I ran up to the fuel pressure regulator I mounted on the inner fender well up near where the battery used to live. The final piece of the puzzle was to get from the regulator up to the carb, and this was a little bit of a pain. I called around and found that really the only way to run an AN fitting on the Weber 38/38 was to press out the existing fitting and drill/tap the carb top. I didn't want to go that route, so long story short, I decided to transistion to 1/4" rubber line after the regulator. I bought some "super-duper" 1/4" hose and a barb adapter to tie in to the regulator. Apparantly this hose was too super-duper to stretch around the flare on the carb inlet. So, I split the line and threw in another filter so I could use the cheapo 1/4" hose from the local parts store that would fit on to the Weber inlet.

Whew! Finally done! Everything worked out pretty well when I fired the car up. I had one little seep that went away with tightening up a fitting. I set the regulator to 3.5 PSI, but it does seem to fluctuate around a bit - however there do not seem to be any signs of fuel starvation or overflowing the bowl. My only complaint is that the fuel pump is LOUD. It came with a thin rubber isolator on the mount, but I am going to put some thicker rubber in there to see if I can quiet it down some more. Hopefully when the back seat is back in that will also help.

I hope this will help anyone else considering te same type of mod. I'll keep the list posted if anything explodes :)

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yep, electric fuel pumps are loud.....curious on why you didn't mount it in the trunk.

what fuel pressure regulator did you use?

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1st- How many feet did you need for this?

2nd- Where did you get that nice clear fuel filter?

not sure where he got his filter, but they are available through NAPA. They sell Replaceable filters inserts for them too. Very small $ & people raved about them in a thread 2 weeks ago.

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I bought a kit from Summit that came with 20' of -6 braided hose and I probably have more than 6' left. Their kit came with a canister fuel filter that was on back order, so I had them substitute the billet inline filter you can see on the inlet to the pump. It is just a screw together piece with a mesh disc inside. The kit also came with a regulator but it only went down to like 5 PSI. Since the recommendations on the Weber is 3.5 PSI, I found a Holley regulator in the catalog that would work and had them substitute that as well.

I didn't mount the pump in the trunk because of what I have heard about mounting the electric fuel pump close to the tank and as low as possible since they do not "suck" well. Does anyone have any experience with mounting it back there? I would love to toss it back there if it would work OK!

And yes...the fancy clear filter came from Napa.

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Are you going to be running twin 40's or 45's in the future? This seems like overkill for anything smaller than a 38/38

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my 75' has elec pump for dcoe's in the trunk, on rt quarter panel aft of the wheel wheel and fwd of the filler neck. works great.

my 73 with same carb setup has the elec pump high on the center of the firewall in the engine compt. it works great too.

so there you have the two extremes of pump placement. they both work fine! it does not have to be in the pass compt where you can hear it. ;-)

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.... how do you know if the rubber inside the braided line has perished from the fuel? Will you replace all the lines every couple of years?

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I've had a couple of those cheap clear filters witht eh replaceable mesh inserts and the both started leaking. Keep a good eye on it- esp if it is one with the plastic threaded barbs. Using it defeats the purpose of all that nice looking braided line in my opinion.

I also had an electric pump in the trunk- above the tank and it worked fine as far as I remember. The intank pump seems like the best option $$'s excluded. For that matter you could pick up an external pump that is sealed and run it tii style. Many cars run the pump under the car without issue.

http://www.walbrofuelpumps.com/

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yes, all fuel lines should be replaced periodically. they dry up and crack. ths cloth covered ones bmw used stock just hide the rubber from visual inspection, resulting in people going way too long before replacing.

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