(Only a Vet will get it.......)

Anyway,

So I go out in the garage this morning, and immediately smell strong gas fumes. I haven't driven the car for a week, so I think maybe there is a leak in a fuel line or that the big allen bolt thing/screen is leaking. Work my way around to the back of the car and huge puddle of fuel all over the floor. I'm a bit confused, pop the engine lid, find the whole left frame rail soaked in fuel, and paint wrinkled. It looks like either the accel pump was shooting fuel straight against the frame rail, or the fuel filter is leaking. But the real question is WHY? I haven't run the car in over a week. So much fuel dumped the fuel gauge went down 1/8 a tank..... Obviously the fuel system is pressurized, but why and why is it still so pressurized after a week? I took the fuel cap off to a big whoosh then left for work,. This was 0530 AM. I get home this afternoon and there is more fuel on the floor........ Hmmmm. I take of the cap again and STILL pressurized.

So obviously the vent in the gas cap is not working, but I'm wondering what the whole vent charcoal filter thing is supposed to do? I thought it was the primary vent for the fuel tank and an emission thing. ON the 912E, there is a take off from the fan housing, that goes to one side of the charcoal canister, and it also has a line for the small vac hose that runs up to the canister in the front of the car which connects to the vent in the tank. Is my fan pressurizing my fuel tank?

First I need to figure out why I am building so much pressure in the tank and that it is not bleeding off...
Second, I need to track down the leak... I dont think it is the accel pump, but the fuel line, or where the fuel line

I've only added fuel once and noticed a pressure release then too, so something is up.....

Any ideas?

Are you a smoker?

You have a fuel filter in your engine bay? Even if it's not the culprit of your current leak, I'd recommend moving it to the front of the car where it's supposed to be.

I see it a lot with air cooled VW's too - people putting fuel filters in the engine bay.
Recipe for a car-b-que.

lol, well, that is where uncle Ferdinand put it.............

Wouldn't have been in the engine bay. Early cars it would've been on the lower passenger side firewall, below the engine bay. 75-76 would've been up front near the fuel tank, where it should've been in the first place.

It's not a 914, its a 912E, the factory fuel filter is in the engine compartment drivers side just in front of the relay box and other electronics.

I MAY have found 1/2 the problem... specifically why the tank being pressurized, but need to confirm.

I used a factory diagram to hook up the charcoal canister and fuel tank vents, but found a couple threads here in 914 world about the factory diagram being wrong, and I also found a couple diagrams showing factory setup differently. (see pics).

The vac canister has a line from the tank (small vacuum line) that goes to an expansion chamber in the front that connects to the fuel tank filler hose/vent. There are two other nipples, one pressurized from the fan, the other goes to teh intake.

It doesnt make sense that this is why the tank was pressurized and held pressure for over a week. I woul dimagine that the fan fould theoretically pressurize the system by pusing air back up to the tank, but I would expect that to bleed off when the car wasnt running. My car sat for a week, then suddenly dumped 3 gallons of gass on my garage floor, and still had a high level of pressure when I unscrewed the cap.

I still need to find the leak too, and why it would just sit for a week then gush, unless something burst. But all new fuel lines, and system, and everything is tight. I ran the fuel pump for 3-4 minutes and of course NADA.......

This is how I hooked it up at first
Click to view attachment

This thread from 914 world shows it differently, and references the pic above as the 'factory being wrong"
Click to view attachment

This image is from PP and is listed as a 76 evap system, and will use this layout.
Click to view attachment

I switched things up and will order a new fuel cap, because at a minimum it clearly is not venting at all. I also have a bunch of things to do tonight so will jump the fuel pump and let it run to see if I can find the leak, and check to see that none of the lines are clogged. I dont think that is the issue because I THINK that the extremem pressure in the tank is what pushed that much fuel out.... Or, perhaps I have aquired a garage gremlin.... Worse comes to worse I will toss the whole thing and just vent from the expansion chamber.

All 3 diagrams look the same to me wrt tank emissions plumbing.
They look correct to me.
The filler cap should be unvented.

Chris, the first pic shows the fan connected to the double side of the charcoal filter This is the way I hooked it up at first.

The second two show the fan being connected to the single outlet side of the charcoal filter.

The arrows on the lines in the first and third pic illustrate.

***UPDATE***
Problem solved, multilayer issue.

The gas leak was NOT any of the new fuel lines, or leak on the carb, it was the capped off fuel return line. Seems that the plugged fuel tank vent issue pushed the fuel up through the OLD fuel return line. I replaced the fuel supply line because it would be used and under pressure, but just capped the fuel return line because it wasnt under pressure, and I assumed it had a check valve, so I used teflon pipe sealant and a brass cap to cap it off and left it tucked in the engine compartment behind the the fuse box.... There was a TON of pressure in the tank because even after sitting for a week, and pushing a gallon or two of fuel on my floor, there was still enough pressure to make the cap pop up when unscrewed.

Definitely wasn't the fan or way things were hooked up to the charcoal canister. Turns out the small vacuum line from the expansion chamber to the rear of the car is plugged. For now, I am just going to run a short line from the expansion tank up through the fender and vent to atmosphere below the headlight/bumper. I may eventually run a new line to the back of the car, and will look to see if there is a way to run a new one, but I'm not really an environmental weenie, so I may just pull the whole charcoal canister and call it a day....

fuel return lines are important
I've always said this and continue to believe, that a fuel return line should be used on any set up including carbs
fuel return lines are important and there hasn't been a car made without one in decades....

I understand your point. It's not uncommon when converting to carbs to use the low pressure pumps and eliminate the need for a regulator and return. I was at one time considering a fuel filter like this, have used them when using a higher pressure fuel pump and carbs on GM V8's. http://www.amazon.com/FRAM-G3583DP-In-Line...r/dp/B000C2ZJRU