So I accidentally drilled a hole in the top of my fuel tank.

usa591 · **Posted:** Mon Aug 17, 2015 12:58 am

…I wish I could say that this was the start of a bad joke, but it's true.

I was installing an eyebolt in the bed and I didn't quite measure correctly. Whoops. I ended up drilling through a plastic tube on top of the tank that seems to be some sort of vent line & putting a 5/16'' hole into the top of the tank. Ha--I said a few choice words when I realized what happened.

I'm wondering two things--from looking at the shop manual I can't tell what that tube does. Secondly, is there any hope in sealing the tank back up or do I need to get a new tank altogether?

I sealed the hole with a piece of foil tape & am hoping that if it's just a tube that allows the two sections of tank to breathe, I can still drive it until I figure out a permanent solution.

Thanks in advance.

flash7210 · **Posted:** Mon Aug 17, 2015 7:35 am

The only problems with having a hole in the top of you fuel tank are:
1. If your vehicle rolls over, fuel will leak out.
2. If you are off roading with a full tank, fuel might slosh out and and water might get in.
3. If you over fill your tank, fuel will leak out. Some folks already have this problem (like me) due to a leaky breather valve.

papaindigo · **Posted:** Mon Aug 17, 2015 11:28 am

Go to http://colorado4wheel.com/manuals/Jeep/KJ/ and get a copy of the 05 FSM which has illustration keys and go to pg 14-72. That's the check valve. I suspect its purpose is to hold the fuel tank vent line closed until tank pressure reaches a certain level. If that's correct and you drilled a hole in the line between the valve and the tank then fuel will vent thru that hole before it reaches the check valve and the line running up the filler pipe. Not a good thing but you can probable repair that line with a bit of marine grade diesel rated fuel line and clamps. Similarly a hole in the tank will vent fuel as flash notes. I'd be "happier" if the hole you drilled (moral never ever drill thru metal with something plastic or rubber behind it without a stop shim in between - let me tell you about my MGA steering boot fiasco) but the tank plastic should be thick enough to accept a screw or be tapped for a bolt (stainless of course). If so get a bolt/screw and washer of the appropriate size and some fuel tank sealing goop from an auto parts store and do the obvious.

Both actions will require dropping the tank. Check threads on the intake fuel pump install on how to drop tank.

65Corvair · **Posted:** Mon Aug 17, 2015 11:32 am

I would assume as well that you have only damaged the vent system on the tank.

For the hole in the tank you could try a well nut, though I am not sure if they are rated for fuel/oil.
http://www.bing.com/search?q=well+nuts

or even just a short bolt with RTV around the head to hold it in place.

With the damaged line you could try rescue tape around the line after it is cleaned up. Most auto part stores sell some type of self vulcanizing tape, usually by electronics/bulbs. I have used this to fix a vacuum line until I bought a new one.
http://www.rescuetape.com/

However, if it is possible to replace the vent lines, I would reccomend that.

usa591 · **Posted:** Mon Aug 17, 2015 12:25 pm

Ha--yes, I've learned a few things about measuring / being a little more careful about drilling into blind spots.

Thanks for the ideas papaindigo and 65Corvair… I wouldn't have thought of the bolt or the wellnut.

Looking at the 2005 KJ manual, I agree that the line I drilled through isn't critical, but I want to get it sealed up quickly.

I had already downloaded the 2006 KJ manual and that check valve wasn't labeled--only the 2005 manual. Interesting.

I'll let you guys know how this turns out…

papaindigo · **Posted:** Mon Aug 17, 2015 2:21 pm

I would not trust an ordinary well nut to be fuel resistant but if you google "well nuts fuel tank" there are well nuts for fuel tanks but since your hole is on the top and the tank is not pressurized to any great extent I think a simply screw in plug will likely do. RTV may or may not be fuel resistant enough. Of course if you can score a proper size fuel resistant well nut for say $20 go for it.

I have to disagree on whether or not the hole in the line is critical. BOTH the line and tank holes would be extremely critical on a gasser. On a diesel they are less so but both places will leak if a) you over fill the tank or b) if fuel expands enough in hot weather and/or c) you park on a significant up slope. As diesel is less flammable than gas such a leak is not extremely critical but it is a hazard and should (must in my opinion) be fixed. The fix is cheap but labor intensive to drop the tank but not a hard DIY job.

Yes if I was in that far I'd a) do the in tank pump mod and b) get rid of both fuel supply line quick disconnects (replace with the hose I mentioned earlier and clamps)

usa591 · **Posted:** Mon Aug 17, 2015 3:25 pm

papaindigo wrote:

I have to disagree on whether or not the hole in the line is critical. BOTH the line and tank holes would be extremely critical on a gasser. On a diesel they are less so but both places will leak if a) you over fill the tank or b) if fuel expands enough in hot weather and/or c) you park on a significant up slope. As diesel is less flammable than gas such a leak is not extremely critical but it is a hazard and should (must in my opinion) be fixed. The fix is cheap but labor intensive to drop the tank but not a hard DIY job.)

Yup, I definitely want to get this fixed--my thinking is that I can drive it for a few days with tape over the holes before effecting a more permanent fix. I'm headed over to the dealership at lunch to inquire about a new breather tube.

Since the tank is relatively thin, I'd be concerned that a regular bolt may work itself out over time. I found a well nut that is made out of neoprene. Can anyone comment on how diesel resistant that might be?

https://tpoparts.com/cat093/index.php?r ... uct_id=229

papaindigo · **Posted:** Mon Aug 17, 2015 3:52 pm

http://mykin.com/rubber-chemical-resistance-chart-2 lists neoprene resistance to diesel oil as "doubtful"
\http://www.customadvanced.com/chemical-resistance-chart.html?chemical=Diesel+Oil&rubber=CR says moderate to severe effect.

Not recommended.

You want something like Viton or Nitrile for a well nut.

I still think a screw or bolt will work and suspect the tank is thicker than you think such that a screw or bolt with appropriate sealant will hold just fine especially if you can find a tape or glue that will bond with the tank material to cover the top of the screw or bolt.

IMHO you are over think the tank hole repair as there are a host of readily available commercial products specifically designed to fix plastic gas tank holes. Your hole is on top and very easy to repair.

Were it my tank I'd fire up my plastic welder, weld the hole shut, and cover it with one of the above products just because I like over kill.

Curious why go to a dealer to find the hose. If there is enough room 2-6" of fuel line and 2 clamps or maybe even zip-ties will fix that line.

usa591 · **Posted:** Mon Aug 17, 2015 4:22 pm

papaindigo wrote:

Curious why go to a dealer to find the hose. If there is enough room 2-6" of fuel line and 2 clamps or maybe even zip-ties will fix that line.

…well, I may have damaged the check valve male fitting as well. I want to see if there's someone there that might be able to comment about how easy it is to replace that piece as well.

They're only 10 minutes away from work, so it's an easy trip.

And, yes, I tend to over-think things like this--it's the instincts I developed from working on boats: through-bolt it with stainless whenever possible, that's what Grandpa used to say.

usa591 · **Posted:** Wed Aug 19, 2015 2:34 pm

For what it's worth, the dealer said a new tank is $529 and it would cost $450 to install. The check valve and breather hose is not sold separately (according to the service tech) and come as a unit with the tank.

He said off the record that I should try the fixes discussed in this thread before resorting to a new tank--which is the route I'm going down as soon as I burn off some more fuel.

papaindigo · **Posted:** Wed Aug 19, 2015 3:12 pm

$450 for 2 hours to drop and replace tank. Seems a bit steep unless they are factoring in pumping a full tank dry; for that price if you have to get the tank do the drop and reinstall yourself. Would be helpful if someone could comment on what function that check valve serves. A simple check valve allows movement in one direction and not the other. If that's all it is grab a metal check valve online for ca. $10 and bypass the OEM one.

65Corvair · **Posted:** Thu Sep 03, 2015 5:13 pm

Did you repair you tank, or still burning off the fuel?

usa591 · **Posted:** Thu Sep 03, 2015 9:04 pm

My shade-tree mechanic neighbor is working on it today. I went with the "threaded bolt plugging the hole" fix. I'll report back in a day or so.

I drive so little, it took me all this time to burn off the fuel in the tank!

usa591 · **Posted:** Sun Sep 06, 2015 3:21 am

Success--will post more soon.

Sent from my iPad using Tapatalk

So I accidentally drilled a hole in the top of my fuel tank.

Who is online