Cutting filler hole for Rear gas tank???

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Sep 13, 2006
Santa Monica, CA
Ok so I dont want to mess up my nice new alum I was wondering what the "proper place" to drill the hole for the filler neck to come out would be?

any pictures and explainations would be great...just for reference...I have the same filler neck piece that UNO has from downey offroad.
Link some pics from others you've seen that you want imput on. That would help anyone trying to help you.

I prefer to have the filler neck above the inlet on the tank. It increases the odds that the breather will also be above the tank [it's usually tacked onto the side of the filler neck. If the breather is not optimally vented, it will cause the tank to 'burp' a lot more. BIG BURPS!:eek:

I like the symmetry of a stock filler neck utilized in a secondary tank as well. I have seen several people set up their aux tanks that way. Filler neck of same vintage as primary. Shouldn't be too hard to plumb it to the aux tank. Yeah it's more work [and you've got to spend the time to hunt one down. But it's something you're gonna have to look at for a LONG TIME to come.

I have one of the old-school ConFerr fillernecks on the 40. Wish I had done the stock. Did one on the 45 and like it much better.


Mark A.
Ditto Mark; I also replaced front w/locking door
cruise & large equip 071 (2).jpg
cruise & large equip 071.jpg
Ok so I dont want to mess up my nice new alum I was wondering what the "proper place" to drill the hole for the filler neck to come out would be?

any pictures and explainations would be great...just for reference...I have the same filler neck piece that UNO has from downey offroad.

You're not going to believe this, but I eyeballed mine. I estimated where the filler line would come out and just hacked away. Based upon the MAF tank you're running, you'll see between the frame rail and the body a gap for the filler hose and air vent to slip through. Line the neck up stright up with the gap and hack away.

You'll want to put your filler neck higher than the the filler for the tank. Should be in the middle of the rear pannel...

I'll take measurments tonight if you really need em.
I wanted mine as high as I could get it. I just took into account about 1" for the lip of the fuel door pocket, and made my mark as high up as I could without interferring with the running lights. If you look at my pics you can see my outlinne in marker where my running light was to be mounted. In placing it this high you also have to cut into the fender well about an inch. I was trying to eliminate any girgling, and fuel tank filling problems.

Once you get everything set up I had a local muffler shop bend me what I believe was a 2" pipe (stainless) to match my old filler neck to the fuel tank input.

I looked for pictures but couldn't find any that I took. I do have the mock up of the filler neck if you'd like to see them let me know.
I put mine in the top of the wheel well. I thing that it is a great spot ( you should not do this if you run a hard top). it dons not leak when the truck is off camber like most do.
This may be a dumb idea, but is it possible to T-off the main fuel inlet hose and re-direct it to an auxilliary tank? That way you could fill either tanks through the same nozzle, to make a cleaner looking setup. Maybe some sort of diverter valve or similar. I thought I remember seeing something like this before on someone's car.

I imagine there would a lot of modifications involved and some long runs of fuel tubing, as well as some other problems, but any other reason it can't be done? I'm not looking at my cruiser right now, so I could be missing something completely obvious.
1st and 2nd pic are self explainatory and the last pic is measured from the of the tub lip. Your cruiser might be different because of the aftermarket tub. So please make your measurements accordingly. Also, look behind the rear quarter to ensure that your filler neck will line up with your fuel housing.

It's likely you'll have to cut your filler neck that was included in the MAF Tank to fit. Find my post about my gas tank installation and study the pics.

Good luck buddy!



One last thing, make sure you use a holesaw to cut, and not a sawsall or somthing that you'll regret using.
What I did was "Y" the OEM filler neck and ran the hose towards the secondary tank. When I fill up I turn the gus pump towards the right and when it tops off I then fill the stock tank as normal. I did have to cut the tub a lil but it is not visable from the outside. It looks stock with a spare tank. Everyone is baffeled how I get gas into the secondary tank. Their eyes pop when they see the "Y" on the stock filler neck. It took some welding but it works great.
I had my filler neck coming out the side and never did like it:frown: So I went a step further. I did not like the old school gas cap that would leak gas all over the place when on a side hill. So I went with the new still screw cap that gos click, click, All you need to do is get utility truck bed filler neck housing a 80's GM truck filler neck and hose off a 82 toy pick up and so for the best improvement I did to my rear tank
fillerneck 2.JPG
I put mine as far back and up as I could and still be on flat surface and not cut through the wheel well. I then went to a muffler shop and had them weld up a filler neck that aligned with the tank fill port.
78FJ40 38.jpg
Fuel Filler 02.jpg
Fuel Filler 03R.jpg
^^^^that is slick. Nice work.

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