Gas Tank Rattle (1 Viewer)

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Joined
Oct 29, 2014
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Finally got my 1970 FJ40 on the road! All things considered it drives really nice. Just some small irritations (I know - it's not a Lexus). Gas tank has an annoying rattle. Took the float out but that's not it. Any ideas?
 
It could be rattling on the floor pan. There should be a piece of foam / matting on the bottom of the tank to help keep it settled and from rattling.
 
I have pieces of padding under the tank and the straps are snug. (This is a complete restoration so everything was gone over.) The rattle is definitely coming from inside the tank.
 
I know my FJ-60 has a bunch of baffles inside the tank, but does the FJ-40 tank? I don't think so, but if could be a loose baffle.

Can you hear the rattle when you shake the truck when you're not driving?

How did you confirm it isn't the fuel sender float?
 
I don't know if the FJ40 tank has baffles or not. I removed the fuel sender float and then tapped on the top of the tank with my hand and the rattle was still there. It does not rattle when I shake the vehicle, just when I'm driving or the engine is idling, or I pound my fist on the tank. Annoying because it is right in the cab beside you. Drives me nuts!
 
Have you checked all the lines going into the tank to make sure none of the fittings are loose / hitting the tank? How about the passenger seat? Anything hitting the tank from the bottom of the seat? Have you tried driving with the seat out?
 
Yes. Lines are all tight and passenger seat is out. It is definitely the tank doing the rattling.
 
Got the felt strips under the straps. Got the little pins that hold the strips in place bent in far enough that they don't touch the tank. Got the pads under the tank. Got the straps tight (even tightened them a bit more just in case). I think I have been fairly careful putting this back together. Let's establish that the rattle is definitely from inside the tank. Just wondering if anyone else experienced this and what they did about it. Hopefully it does not mean buying a new tank!!
 
Have you tried draining the tank, and using a flexible magnetic tool to see if there's a loose piece of metal in there? I bet that'll be tricky since it's all metal.

Hmmm. What about using something flexible but non magnetic to feel around in there?
 
A few years back I cut a portion of the top out of a fuel tank from a 68 and yes it had Baffles and the suction tube was just a piece of copper or steel tubing can`t remember which, just bent from the side of tank down to the bottom or at least close to the bottom. your rattle could be the pick up tube or a baffle.
 
Maybe a 10mm socket that is MIA.

Maybe it is a gremlin trying to get loose in the tank.

I think you should drop it of with me, I will personally perform a thorough investigation into this rattle you speak of.
 
Gas tank rattle.

My Father-in-law had a '68 GMC stepside, (pre-unleaded) fuel tank behind the seat, that had a rattle every time he hit a bump or took a corner. This was in the mid-1970's.

When I asked him whats up, he told me he was filling his tank (during the '73 oil embargo) with his 2 gallon lawnmower can and the flex metal spout came unscrewed, and fell down the neck of the truck's fuel tank.

Rattle, rattle.
 
Thanks everyone for advice and comments. Interesting. rkymtnflyfisher - Ill let you know if it is a gremlin after my thorough investigation. Had the tank off previously and the only thing in there was the chain off the cap. No flex metal spout or anything like that.
Never a dull moment on "mud".
 
No updates. It's at the mechanic getting checked out for other miscellaneous glitches before I really start driving it. They might take a look at it. Will keep you posted.

Thanks.
 

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