2nd Fuel tank on my Deuce.

So I've hung the second fuel tank and am now working on the plumbing and wiring. I've been stumped for the past few days on the issue of powering the fuel pumps alternatingly. I initially thought to power them off the mains from the cab and split the feed to the right side pump so I could power the left pump instead via a DPDT switch. But short of cutting into the wiring harness at the cab under the dash (not easy to do there either) I'm stuck having to install a relay at the right side fuel tank. This could be simple though because I can easily run a single throw switch in the cab and have it's feed just activate the left side pump and Only cut the power lead at the RH fuel tank. I might be able to take apart the fitting and modify it there though I'll probably put a pair of packard connectors in so it can be reverted back to normal easily.

Anyhow, this needs a relay. I want one that's weather proof and has a DPDT setting. I'll power one side to switch to the left side fuel tank but otherwise it'll power the right side fuel tank absent switch power.

The 2nd fuel gauge is mounted in my dash nicely and I relocated the high beam lamp and added a splitter for the power to the second fuel gauge off of the "spider" harness.

Drilling the frame wasn't too hard. I REALLY like the real titanium coated bits. Run them at high speed with plenty of oil and pressure on the drill and they cut nicely.

I'm going to intercept the fuel supply and return lines at the right side of the frame rail near the right hand fuel tank and run either copper lines from those points and then to rubber lines to the cab fuel selector switch which will go next to the parking brake. I'm waiting on Memphis Equipment to send that. The vent is going to get combined with the other 3/16" tube vent on the right side frame rail and go forwards to the main 3/8" vent tube that runs to the road draft tube. The nice thing about my tubing mod is it'll be easily converted back as well with a couple of inverted flare connectors. Basically I'm going to cut the existing tubes, install flare nuts, install some 90° bends and then run the 4 lines to the valve at the left side of the cab. It'll take some extra fittings but it won't need a lot of tubing which isn't cheap.

So, anyone have any advice on relays. I can't seem to find a good example of a 24vdc capable relay that'll have a DPDT configuration that's not $$$$ and I know will work in the weather. Bjorn, how much did your relay's cost? I suppose I could get a more standard relay and put that inside a small weatherproof project box.

Don't worry, I'll get pictures when it's all done.

Ryan, these may work for you. Just read the spec and install them accordingly.
I like to use mil spec relays, which are hermetically sealed, typically made by Leach or Cutler Hammer. Do a search. About $12-15 ea.

http://cgi.ebay.com/6-P-B-Plug-in-P...6405301QQihZ019QQcategoryZ78205QQcmdZViewItem

Ryan, do you have pictures of the mounts installed before putting the new tank on?

Not really. They're pretty straightforward in installation. 4 bolts per "L". They're tricky to install as the bolt holes have to be done carefully so you don't cut wires or worse puncture fuel/brake/air lines which run on the inside of that frame rail. 3/8" bolts are used, grade 8. I used a slightly oversize drill so I could have a little bit of wiggle room.

I'd be inclined to run a lne across the truck and use the left tank to refill the right tank while running. Might be a simpler installation but thats just my opinion.

Perhaps, but with two separate systems, he has the option of running different fuels in the future. Biodiesel or veggie oil....

Yeah, guess I forgot about that option.

I'm going to go with two seperate systems because lets say the right tank gets puntured then all your fuel from the left would be wasted (if you run from left to right) or you loss the right pump you would still have the left. but then again im 16 what do I know.

The plan is for the capability to run alternate fuels from the left side tank. I'm going to hopefully add either a heating coil like Bjorn or a small heat exchanger (radiator) to the inside of the tank. Though coil of tubing would be easier.

Still, 110 gallons of fuel will make for more range than my butt can handle.

Shewt Ryan, 50 gallons is more than my bladder can handle.

Ok, Pictures are up.

http://www.freakchylde.net/~ryangill/M35w1100Singles/M35w1100Singles.html





I think I'm going to install the selector switch in one of these holes in the dash. That'll activate the relay that'll throw the reed to run the other pump.

Two fuel gauges are nice, Ryan, I might upgrade from the selector switch one day (as if I needed another gauge...).

Any idea if there's an easy way to calibrate the fuel gauges? (Bend the float arm?)

Also, the wiring isn't even done yet. I've got the ground lead roughly connected to the frame, but I need the 2 pin boot and need to run wires to the other side for the power for the pump and the gauge to the cab. I'll probably get a metal project box for the relay to go into. Turns out Grainger has these in stock so I can probably go into their shop and pick one out from stock.

Ok, I've installed the relay box and relay plus switch and finished all the wiring for the fuel system. Now the left side pump runs when I hit the switch and the right side stops. I'll post pictures tomorrow.

What relays did you end up with? The mil spec ones won't need an enclosure. I'll post a picture later of my relay set mounted behind the companion seat.

I bought a 24 volt, 10 amp relay from a local industrial electronics supply house. They also had a nice aluminum project box that I mounted the base in that allows for those contacts to be safely sealed from the elements. I tried testing it last night then got nothing when I threw the switch. I think realized I hadn't connected the ground for the coil, fixed that and it was good. Now I need to do the plumbing for the supply and return feeds.

My M52 has a switch for left and right tanks. But the pass side tank pumps into the drivers side to refill it. I'll probally just run a hose between the two and let them equalize them selves. The guage reads both tanks from the switch and you have to throw a pump switch to fill the drivers side.

Ok, wiring is all done and neatened up. I even wrapped the wiring at the tank on the right with friction tape and electrical tape over the top of that.

Web Gallery:
http://www.freakchylde.net/~ryangill/M35-second tank/M35-second tank.html

Looks like it will work Ryan. If your "project box" has a gasket, make sure you drill a small vent hole in the bottom. Condensation will otherwise fill it with water. Constant changes in barometric pressure will pump humid air past any rubber type seal. That's why I like to use hermetically sealed relays (mil-spec).
Image shows my headlight and turn signal relay panel for the 8x8.

I've sealed all the holes with silicone gasket maker. I'll let it cycle a few times then see what it looks like inside in a few days. We're getting fronts through here constantly that are hot, cold and then hot again with lots of changes in humidity and pressure.