Ok, looking for tips and suggestions on what to check next
hoping that someone has seen something similar and I can benefit from your experience.


so this is my street car (1974 2.0/4 with Djet)
drove 2500 miles in march 2015 with no problems

new under tank fuel lines and filter changed as a maintenance item before the trip
(I have metal brake lines in the center tunnel, so the rubber fuel lines run from tank to tunnel, and in the engine bay from tunnel to fuel injection)

I checked the fuel log, and it was filled (full tank) in april 2015
I've driven it on short trips over the summer including 100+ miles in early June

so approximately early July I decide to take it on a short trip/errand and it starts right up in the garage. I pull out onto the driveway and smell gasoline

I leave it running and pull the brake, go to the front of the car and look underneath
where the gravel pan is (covering the stock fuel pump under the tank) I see a drip drip drip (not pouring) Car has maybe 1/2 tank of fuel at this point.

I pull it back into the garage and drive something else. next day I put it on the lift and pull the gravel pan. everything is dry, so I start the car. still no leak.

I cut my zip ties (used to hold the lines up out of the way) and wiggle all fuel lines, check all hose clamps, using a flashlight I examine the fuel pump....
all of this with the motor running and idling
but no leaks.

so I reassemble the pan, test drive, and look for leaks the next couple of times I pull the car out. it remains dry

- On Tuesday this week, I take the car for a 10 mile drive without problem
- On Wednesday I visit ginter (30 mile drive) with no problem and realize I'm below a 1/4 tank of gas so fill up on my way home.
- last night... Thursday (24 hours later). I grab the car for a run up the mountains. I pull out of the drive way and while driving through the neighborhood (top off) I smell fuel


I pull over to the side of the road, idle for a minute, then pull forward and look over my shoulder. Sure enough small puddle of fuel that looks like it was coming from the area under the fuel tank

I'm late and frustrated, so drive on
10 miles later I get to a buddy house and while the car is running, I park and look underneath. Everything is dry. No leak, no fuel smell

I drive another 50 miles, still dry


So what is leaking and then going away?

-fuel lines new/filter

-old stock pump that could be loosing a seal??? but its sitting not dry when there is gas in the tank... and weird that it would only leak when I first start the car

-maybe the stock breather/vapor system on top of the tank... but weird that the first time the tank was half full.... last night it was full so I can see it expanding/running over maybe on a full tank?

-maybe a pin hole leak on the tank? I can pull the tank and check, but how the heck does it stop leaking if there is a pin hole?



I'm open to suggestions. I'll pull the vapor recovery system tonight and look it over... but what have others experienced that was similar

probably completely unrelated... but the car started to hunt at idle this week when cold. 1100rpm - 400rpm
runs rock steady at 900rpm when warmed up.. and its not done this prior to this week.... (I doubt its related, but can test the fuel pressure? even though my gut is telling me to check the decel valve and AAR)


TIA!!
brant

Pin hole leak; just had this happen

in the tank itself?

did yours come and go intermittently over a 2 month period?

can I pressurize the tank to find it?

(damn.... I wish I hadn't just filled it to the brim)

It OK, it will be empty in no time.

There's some yellow tube (can't remember the product name) but it will plug a leaking tank even while it's dripping; wonderful stuff, haven't used it for many years when i was poor

Do you have enough rubber hose under the tank to pull the tank w/o removing the hoses? If so, lift the tank and inspect.

Probably close to enough. But once I drain 15 gallons it's only one more hose clamp away from coming out.

Yup, I discovered one las month as well , I was cleaning the tank , removed the sending unit ? Peeped inside to check the condition and to my surprise was two pin holes.

Have you recently by chance added an amp or anything screwed to the trunk wall or under dash and possibly drilled into the gas tank? I did this years ago on a old VW bus when I added a hard start relay to the floor above the starter motor. Bad choice for mounting was apparent right away with the stream of gas coming out the screw hole.

Had about the same issue a few years back. Checked everything and then finally removed the tank. The two horsehair pads on the cockpit bulkhead between the gas tank and the bulkhead retained water from washings and stayed wet enough to rust several holes in the tank. Had the tank welded up and reinstalled without the old pads. I think I used pieces of thin neoprene.

Me too. Pin hole about 1/2 way up the tank, wouldn't leak when it was less than half full until the fuel pump pressurized the tank. I changed all the things that you did and still smelled gas every time I started it up. If it had any more than 1/8 of a tank it would drip for awhile after driving and then stop until I started it up next. Finally (about the 4th time I pulled the tank) found a 3/16 hole in the back of the tank where the DPO drilled for a ground wire for a radio or something under the dash.

I agree with others Brant. Pin hole leak. I had the same thing when FourBlades had my car over at his house. I never saw it when I had the tank out, but he tested it, found it and welded it.

awesome
as much as I don't want to drain the tank
it makes me feel better to gain from everyone's experience
at least there is a good chance I can solve the problem!
thanks a ton everyone!

brant

With a little extra hose, I can lift the tank out with everything connected.

Click to view attachment

Tank is connected. I put some fuel in to test all the connections before lowering the tank in place.

Click to view attachment

Brant,

If you need another tank, I have two with all associated hardware.

You should pull the tank, no question. However, the fact that it's happening when the pump is energized would make you think that it's a fuel line.

Got a start here if you need it -
Correct hose sizes rated for fuel injection, with filter

http://shop.914rubber.com/Fuel-filter-and-...m?categoryId=-1

Going to pull it today and see if that's It.
Then go through my parts and see if it have one any better or not???
Might be interested. Should know today

You should swing over and tell me about the charity race

The leak is at the felt mat that is used as a cushion between the tank and the sheet metal. It holds water and will rust the tank. The leak only shows up when you fill the tank with over 10 gallon or more. This happened to me years ago.

I have a UV dye kit that works with fuel and oil (and coolant..how dare I mention coolant here!)

UV dye kit.

You can find them cheaper, but this gives you a general idea if you have never seen them.

Update.

Pulled everything this afternoon

The tank was actually ok
I did clean/scrub/treat/paint that pad area
Pad is in the trash can now

Realized that 28 years s ago I "restored" or cleaned and repainted this tank.
Looks like it was a hose junction.
Dry now with a 2nd clamp/ new hose just to be safe

Test drive tomorrow to verify

I think I need to add a 1975 fuel pump door and simplify my set up. Anyone have tips/threads?

Glad you found the issue. Amazing how one drop of gas can stink up the whole car.

Here's what I did to make a fuel pump door to my '71.

Fuel Pump Door Fab

Finished product is further down the thread on the next page.