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Old 04-24-2010, 12:21 PM   #1
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Default Leaking fuel tank lid

How do you stop a fuel tank lid from leaking? On my DBX lately, after a 1 tank run, the entire car is soaked with fuel, it's getting by the tank lid somehow. The tank is tight, if I pinch the gas line and use an air compressor to pressurize the tank via the exhaust hose nothing comes out until the top pops open from the pressure so I know I don't have a hole. I think the vibrations are loosening the seal of the o-ring somehow while it's running and letting fuel by. The problem is worse when the ambient temp is higher (about 85F right now) and it seems the more time I spend at high RPM the more fuel that comes out. The lid spring seems normal. Are there any tanks with a screw-on lid? Does anyone have any tips?
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Old 04-24-2010, 12:33 PM   #2
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If the rubber seal is good,try putting more tension on the spring....had the same problem on a 8 truggy.
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Old 04-24-2010, 01:39 PM   #3
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You don't want a screw-on lid - you'll hate it. We stopped using those more than 25 years ago and never looked back. If the cap is staying closed when it's pressurized with an air compressor, then I don't think this is your issue. Check for a split in the pressure line that goes into the lid, or that the tank isn't cracked. Is the tank itself wet, or just the chassis. If it's just the chassis, the tank may be split on the bottom. If so, install the new tank with an O-ring between the chassis and the fuel tank standoffs.
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Old 04-24-2010, 01:48 PM   #4
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pressure check all fuel line between tank to carb think will find litlle hole somewhere you proved tank is not leaking
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Old 04-24-2010, 02:05 PM   #5
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Yeah I might consider replacing the tank and being done with it.
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Old 04-24-2010, 03:15 PM   #6
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It's definitely the lid. If I start with a full tank and drive it one lap carefully (no jumps, etc..), when I get back the top of the tank is soaked but it hasn't soaked the rest of the car yet. I think the vibrations are causing the fuel to get by the o-ring. Maybe a new fatter o-ring would do the trick? Any where to get these? If not then I guess my only option is to try a new fuel tank...
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Old 04-25-2010, 12:22 AM   #7
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Default So true Steve

I had a screw on cap on my Original Inferno DX. Hated it. Well didn't know any better that long ago, My first 1/8th scale buggy was the OFNA HODR It was really nice, Lasted forever. Jumped like a brick though. I loved my Inferno though. I won more races with that buggy....Ahh Memories. I'm really glad 1/8th scale nitro has become so popular. It was always my favorite class. I used to have to drive it in fields and so on, because it was mostly 1/10 scale rc 10's and so on, but I always had a big buggy just for fun. Lovin the racin....
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Old 04-25-2010, 04:50 AM   #8
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Default new o ring

Go to napa they have a wide range of orings that will work just tell them it will see fuel. Usualy the orange ones hold up well.
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Old 04-25-2010, 12:50 PM   #9
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Partial success.. Went to the local Ace and all they had was black o-rings. Got one that fit nice and tight and presto no more leak! And my tuning was suddenly about 1/2 turn to rich if you can believe that. Well.. on the 3rd tank suddenly it's very lean again, so I bring it in and it's leaking again. The black o-ring apparently isn't compatible with nitro fuel because it swole up so big the lid would no longer close on the tank.... so the hunt for a fuel safe o-ring continues!
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Old 04-25-2010, 01:50 PM   #10
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the black o rings crack when introduced to nitromethanol. take the stock o ring (you saved it right?) to the hobby shop and compare it to the orange traxxas o rings for their revo tanks. the orange ones are made from a different stuff that doesnt react foul to nitro. silicone orings will work for a very short time but they swell (become larger) in the presence of nitro.
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Old 04-25-2010, 02:16 PM   #11
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You gotta use Silicone O-rings for Nitro fuel.. There is another type that works too, but I can't remember the name.. About any of the colored O-Rings work..
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Old 04-25-2010, 05:29 PM   #12
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I had the exact same issue as you did last week. I used a black oring and it swelled up, so I went the local auto store and presto, in the HELP section they have a set of Metric Orings that are orange, and sure enough the size you will need!
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Old 04-25-2010, 08:20 PM   #13
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Try some throttle linkage collots in the ends of the springs to make the springs stiffer. I do that to all of my fuel tanks. No more leaking caps.
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