Diesel overfill?

linewarbr · **Posted:** Wed Mar 11, 2009 1:12 pm

Is there an overflow valve inside the body panel, around the fuel filler neck? Let me tell you why I ask. . .

I have had a CEL on for about 3 weeks now. Took it to Autozone, their scanner said "No Code," but the Lib is running tip-top. I even changed the oil about 1500 miles early just in case, replaced with Wix filter and Mobil 1 5W-40 Full Synth. Still on.

So this morning, after driving high-speed for roughly 45 minutes, I stop at Chevron to fill up before going in to work. I always "top-off" a little after the pump cuts off, eyeballing the fuel bubbles to not spill any. As I did that this morning, diesel suddenly started leaking down the inside of the wheel well and off the side of the fuel tank, but not out of the open side of the fuel filler. Does anyone know if there is a vent for the fuel filler behind the body wall?

tonycrd · **Posted:** Wed Mar 11, 2009 1:29 pm

The fueltank breather is in that area. Could be that fuel spilled out of it.

bugnout · **Posted:** Wed Mar 11, 2009 1:44 pm

Could be the filler hose came loose from the filler neck/door assy. There is a clamp at the tank and another at the bottom of the filler neck. You can easily get to the one at the tank, but I think you have to reach way up to get the one off at the filler neck.

There is a tank vent directly on top of the fuel tank on the filler (drivers) side, if it was coming out of this, you'd see it on the side of the plastic fuel tank, Don't think you'd see it in the wheel well.

BVCRD · **Posted:** Wed Mar 11, 2009 1:53 pm

Mine will leak if I try to add more after it clicks off.

linewarbr · **Posted:** Wed Mar 11, 2009 2:15 pm

So did my having just finished a 45 minute highway slog have something to do with it? This has never happened before. Ambient temp was about 65 degrees and high humidity, maybe putting cool fuel into an almost-empty warmed-up fuel tank?

linewarbr · **Posted:** Wed Mar 11, 2009 2:17 pm

Also, I'm wondering if this may be why my CEL has been on - since it doesn't want to deliver a code to the scanner. . . I know it will come on if you leave the fuel cap off and drive. Maybe hose is loose at the top, and the CPU thinks the cap is off? Or because I leave it running when I fill the tank?

Joe Romas · **Posted:** Wed Mar 11, 2009 2:24 pm

Like bugnout said :lol:

If you reach way up you can possibly position it higher on the clips :wink:

The breather hose is held to the filler pipe with 2 as I recall plastic clips and when I put my tank back in I positioned it around 3 inches higher and it does not come out the breather easily now

You most likely have gotten a foamy batch of fuel as it can varie between batches. Foaming is one measure of fuel quality, no foam=good

nursecosmo · **Posted:** Wed Mar 11, 2009 2:42 pm

linewarbr wrote:

Also, I'm wondering if this may be why my CEL has been on - since it doesn't want to deliver a code to the scanner. . . I know it will come on if you leave the fuel cap off and drive. Maybe hose is loose at the top, and the CPU thinks the cap is off? Or because I leave it running when I fill the tank?

A loose or removed fuel cap won't cause a CEL in the CRD. There is no pressure sensor in the diesel like there is in a gasser. In the CRD there is sometimes vacuum and sometimes pressure. I think that GMCTD determined it to be +/- 1 psi. I would try a different autoparts store if Autozone's scanner could not read the code. Good luck.

BVCRD · **Posted:** Wed Mar 11, 2009 3:26 pm

linewarbr wrote:

So did my having just finished a 45 minute highway slog have something to do with it? This has never happened before. Ambient temp was about 65 degrees and high humidity, maybe putting cool fuel into an almost-empty warmed-up fuel tank?

Oddly enough, the fuel temp was close to 65 itself. This did nothing.

gmctd · **Posted:** Wed Mar 11, 2009 3:28 pm

The main tank-vent attaches to the side of the filler neck about 3/4ers way up - clamp could be loosened, or hose split - correct on the anti-foaming vent, same side rear of the tank - if you get leak outta there, you got real problems...........

Squeeto · **Posted:** Mon Apr 20, 2009 12:56 pm

Quote:

anti-foaming vent, same side rear of the tank - if you get leak outta there, you got real problems.

Fueled up at a new location yesterday and I had diesel come out of a small plastic cap at the rear-top-left side of the tank. First time this has ever happened so I guessed that the automatic shutoff for the pump was a little off. But you say this may be foamy diesel?

The truck seems to be running fine but I sure don't like to hear "you got real problems". What is the issue beyond the typical air in the fuel filter and poor running engine? And what to do?

ebbnflow · **Posted:** Thu Aug 12, 2010 9:15 pm

Bump. This thread has been dormant for a while.

I don't have a CEL though.

This happens to me too. I fill up with B100 at home so I do not have the fancy gas station style nozzle. Every time I fill up, I can see fuel in the filler neck, it does not spill out where the fuel goes in, but it leaves a spot on the garage floor and looks like it runs down the back of the tank on the drivers side. Is this normal and OK? Thanks.

ebbnflow · **Posted:** Thu Sep 02, 2010 6:21 pm

bump.

geordi · **Posted:** Thu Sep 02, 2010 6:32 pm

Y'all must have leaky breathers, or my tank just doesn't have that. I fill it all the way up to the top of the neck, and depending on the nozzle's foam-output, I might actually get it where it isn't still a tube full of foam.

Point of interest: I pulled my filler neck out and removed the interior barriers so that the truck nozzles will fit it. I (can't remember why) ended up cutting the top of the neck and making a connecting collar with a small section of silicone tube. I do not recall doing anything special with the breather tube, or even really remember seeing it at all.

I don't see anything drooling onto the ground at all. I'm going to fill up tonight, I will make a point to look under the truck and see if I see anything.

dkenny · **Posted:** Fri Sep 03, 2010 7:13 am

yes there is a tube. its about 3/4" in diameter it should run all the back to the top of the fill tube. the problem is the connection between a couple of different tubes/pipes. most have no clamps..

and yes there a small breather in the upper left rear of the tank than can leak. I fixed my wifes but removing the little plastic thing and attaching a hose. then I routed this hose next to the filler tube. no more leaks

-dkenny

salden77 · **Joined:** Tue Jun 01, 2010 2:42 pm **Posts:** 271

mine did that once when i was topping it off, i looked underneath the jeep and it looked like there was some kind of breather valve thats on the drivers side back corner of the tank on the top side that the leak was coming from, it hasn't happened since that time though.

Diesel overfill?

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