Overfilled fuel tank

[das76]

Rookie mistake: I accidentally overfilled the fuel tank. Fuel leaked out and was coming out from under the car. Is there anything to be concerned about or is that the ways it’s designed to overflow ?  I should have taken some pics. 
 

The car is 2005. Should the tank be inspected due to age ? 

[MV8]

Doubt it is a tank problem but pics of the tank and fill and vent plumbing could help. Many methods to tackle thermal expansion of cold fuel from in-ground station tanks, cornering slosh, accidents, and roll overs. Previous discussion and methods:

 

[IamScotticus]

Gas is pretty harmless unless its on paint.  Don't wipe wet gas off paint, let it dry first.

let it dry, avoid doing hot electrical work in the area.

Clean the area with a diluted degreaser.

[das76]

Thanks. it didn't go on the paint, just leaked through the bottom. it stank for several days, but I took the boot cover off and that seems to have done the trick.

Now i leave the key in the ignition and turned so I can see the gauge move to Full when i'm filling up !

[das76]

@IamScotticus when it leaked out in was inside the boot, it wasn't coming out where the fuel filler goes in. Is it designed to do that, or does that mean i might have a crack or hole somewhere?

 

 

[IamScotticus]

Because many causes are not visible, just start with eliminating the usual suspects.

You may have had a leak you didn't discover until now.

 

Firstly,  if messing around with fuel components 💥☠️, disconnect the battery.  Just do it. Until you get everything back together.

 

Pressure/venting.  All fuel tanks need venting of some kind.  Excessive tank pressures, positive or negative pressure,  can produce leaks. Inspection stations had gas cap pressure testing equipment.  See if you have a vented cap and test it. 

If the rubber components like hoses, necks, caps etc. are old, ten years or more, the exteriors may look good but the rubber could be hard and gaps open under the clamps, especially if the clamps are non-expanding like worm gear types.  Everything on a 7 gets rattled and shaken.  Rubber fuel lines that have hardened can get cracks. 

Just replace every rubber fuel part back there if its old.  Just do it as a maintenance item.  Same can be said for rubber brakes lines.

 

During the part replacement process,  drain the tank, cap all the barbs and pressure test the tank with a leak-down test.  Dont put so much pressure that you hear a hiss, just enough to get about 15 psi on a gauge and let it sit for an hour.  A quick loss of pressure will be an immediate clue.

To test the tank its probably easier to cap the filler neck with a big cap and attach a vaccuum pump like a Mighty-Vac to a smaller barb like a vent or the fuel outlet.  Unless you have a bladder or foam filled, you may not get enough gas out to use the fuel outlet.

 

As for the overfilling,

I have had the initiation ritual of being chatted up by people at the fuel pump with the usual questions and admiration.  Just as Im so glowing with pride, proud of myself that I have such an awesome toy, my leg get showered with gas, in front of everyone 😬.

It is for this reason, and another reason,  that I will no longer use the bent filler neck.  I will use a straight rubber riser (fuel grade) under the boot cover.  This way I can see the fuel level, or use a stick.

 

My fuel tank filler neck diameter is 2.25".  if that helps.

 

Edited May 6, 2023 by IamScotticus

[das76]

Up to now I've been simply cautious have have the ignition turned on so I can see the gauge. Now I'm finally getting to some of the projects on my car since I just wanted to drive it last summer and fall.

 

Today I pulled off the boot floor and found this gasket is obviously toast!  I looked on the Caterham Parts website and I can't find the gasket (they do show the right side gasket, but not the top gasket).

 

Does anyone know the part #?

 

(Caterham Parts shows this one, but doesn't mention it's for my car with Zetec: https://caterhamparts.co.uk/pumps-senders/1989-fuel-pump-gasket-sigma-duratec.html)

 

 

[MV8]

I'd pickup cork gasket material from online or the local auto parts store if they have it 1/4" thick (though thinner may be acceptable), then trace and cut out with an exacto blade. Doesn't need to be any larger than the sender flange. Looks like a curious cat pulled on that one. Make the gasket id as small or a little smaller than the tank opening.

[ashyers]

das76,

Search “fuel AND tank AND gasket”. It’s a common issue. The gasket is from a Mini. I’ll see if I can dig up the P/N. I found a cork replacement at Rock Auto and installed it with fuel proof sealant. No issues since.

Andy

Edited February 9 by ashyers
Found it!

[das76]

Thanks @ashyers . I think I have solved the mystery! (really not much of one in the end). I think what stumped me was I wasn't expecting the design of the right side gasket (for the fuel pump) to look so different so I thought the above style gasket with the 6 screw holes was for the fuel pump on the side. 

 

I found both parts listed here: https://caterhamparts.co.uk/149-gaskets 

 

This one is for the right side pump which I also need to place: https://caterhamparts.co.uk/gaskets/92-gasket-fuel-pump-side-moun.html - this is also a Mini part used on the fuel injected cars of the 90's

 

This one is for the sender at the top of the tank: https://caterhamparts.co.uk/gaskets/96-fuel-tank-sender-gasket.html 

 

Of course no stock at Caterham, so i'll try USA sources or Redline

[toldfield]

You might try Moss Motors.

[Taber10]

I strongly recommend NOT using the Caterham supplied gasket on the side of the tank.  The "square" holes apparently allow the gasket to be used in a wider variety of tanks, but the larger than necessary bolt holes lead to failure and leaks! Find some fuel resistant gasket material--I found it at a local hardware store--and cut out a gasket then punch holes for the bolt that CLOSELY match the size of the bolts.  I'm thinking 1/4 inch but that was years ago.  I used THREE of the "mini" gaskets and they didn't last long.  The gasket I made and sealed with marine grade sealant, has lasted for over ten years with no leakage.  

[Stang70Fastback]

Ok, maybe someone here can help me, because I've posted about this in several FB groups and haven't yet found a good resolution. I've had my Caterham since last fall. For winter, I brimmed the tank, and parked the car, only to notice a pretty strong odor of fuel, and then... a river of fuel running across the garage floor. Long story short, I pulled the trunk cover and found that the fuel sender gasket had completely disintegrated (it's a '93.) So I bought new cork gasket material and made a new gasket. All good, right?

Well, no. Because it appears that my tank is vented in the dumbest way possible: a small hole drilled right on the sending unit cover itself - and not just drilled anywhere, but right on the indented ring that normally seals against the gasket. In the attached photo, you can see it in the lower right, between the two bolts. So, I have a few questions:
 

1. Is this just how it was done in the early 90s, or is this some weird hodge-podge solution? I can't find a separate vent line ANYWHERE on the tank, unless I'm missing something obvious, so I suspect this is the only venting my tank has.
2. For the love of god, does ANYONE know where I can find a complete replacement sending unit for this tank with this bolt pattern? That's where nobody has been able to help me. Ideally I'd like to replace the sending unit entirely (since it's 30 years old), and what I'll do with the new one is drill a hole in the MIDDLE (not where the gasket seals) so that I can install a vent line with a check valve and stop this stupid dribbling of fuel when the tank is full, or when I accelerate, or when I jack up the car.

[7Westfield]

The answer to question #1 is probably yes....and yes

My prelit had a hole in the plate with a 1/4" pipe elbow on it, always wet

If you do put another fitting in the plate, use an AN bulkhead fitting with a stat-o-seal washer

A gob of epoxy should seal that hole, or a zap with the MIG

How close is the gauge hole to an edge of the tank? Is it close enough that you could put a bulkhead fitting in the front or end of the tank near the top?

 

when I built my new tank, I used  weld-on bungs

 

When looking for a new sender, you also need to match the resistance to the gauge

Edited February 11 by 7Westfield

[MV8]

14 hours ago, Stang70Fastback said:

Ok, maybe someone here can help me, because I've posted about this in several FB groups and haven't yet found a good resolution. I've had my Caterham since last fall. For winter, I brimmed the tank, and parked the car, only to notice a pretty strong odor of fuel, and then... a river of fuel running across the garage floor. Long story short, I pulled the trunk cover and found that the fuel sender gasket had completely disintegrated (it's a '93.) So I bought new cork gasket material and made a new gasket. All good, right?

Well, no. Because it appears that my tank is vented in the dumbest way possible: a small hole drilled right on the sending unit cover itself - and not just drilled anywhere, but right on the indented ring that normally seals against the gasket. In the attached photo, you can see it in the lower right, between the two bolts. So, I have a few questions:
 

1. Is this just how it was done in the early 90s, or is this some weird hodge-podge solution? I can't find a separate vent line ANYWHERE on the tank, unless I'm missing something obvious, so I suspect this is the only venting my tank has.
2. For the love of god, does ANYONE know where I can find a complete replacement sending unit for this tank with this bolt pattern? That's where nobody has been able to help me. Ideally I'd like to replace the sending unit entirely (since it's 30 years old), and what I'll do with the new one is drill a hole in the MIDDLE (not where the gasket seals) so that I can install a vent line with a check valve and stop this stupid dribbling of fuel when the tank is full, or when I accelerate, or when I jack up the car.

They seem to have all gone to 5 bolts. I don't expect the bolt circle is the same either. I like the stainless marine cylinder type with only the float exposed to water/fuel. Limited options on matching the resistance to your original gauge but there are converters.

Consider adding a vent port to the cap neck or a tee between the tank and cap, then it should never be under pressure to push through the sender flange hole.

If you must weld or braze the sender flange, it will lose the fuel resistant rust prevention.

Another option is to cut a 1/8-1/4 thick aluminum ring the od of the sender flange, then mill a clearance groove for the original flange, making a flat flange above the gasket, but it might require longer screws.

Edited February 12 by MV8