Gas gas gas

Bulldog9 · 04:49 PM

(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. Though the 912E is basically a 911 with a 914 derived motor, 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.....

Reiver · 12-08-2015, 04:49 PM

! thousand, 2 thousand, 3 thousand......

Check your fuel pressure regulator next to the filter...it retains pressure and fuel...enough ot make a mess and it could squirt all over the rail if it failed somewhere.
The canister simply deals with fumes and there is no pressure etc.
Since the fuel evaps so quickly it will be hard to find unless you run a test....standing by with a proper extinguisher have someone turn the key (no start) far enough to get the fuel pump going and watch closely.....not a fun technique but it is prob what I'd resort too.
There may be a safer way to check and I'm sure someone here may have one....wait for more responses.

manbridge 74 · 12-08-2015, 05:08 PM

This may sound like it's from left field but the answer to ethanol based classic car fuel system degradation lies in elections and whom one votes for.

Merry Christmas!

kiwiokie · 12-08-2015, 05:20 PM

Thought this thread was going to be about the Rolling Stones????

Erichter · Erichter's Garage

I hope you don't have a natural gas fired water heater in your garage

Bulldog9 · 12-08-2015, 06:03 PM

Sorry guys my project is new to this forum, all the components are NEW, is a complete teardown and rebuild of a 912E. I just installed the fuel lines, running a low pressure carter pump,n no regular, and new right sized fuel lines from aircooled.net. Not sure how effective it is, but I add a full can of seafoam to every tank of fuel on all my car'b vehicles, and try only to fill when empty to keep balance of fuel and additive consistent as possible.

manbridge 74 · 12-08-2015, 09:01 PM

LOL, I love natural gas and am currently being warmed by its awesomeness.

Have you considered pressure testing your new pump's fuel pressure? Carbs need 3-5 psi. Maybe you are getting more?

matthewb0051 · matthewb0051's Garage

I got immediately and started looking for my pro mask. I've even have my kids doing the proper arm signals and saying the words when someone cuts the proverbial cheese.

Bulldog9 · 12-09-2015, 08:12 PM

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 the intake.

It doesn't make sense that this is why the tank was pressurized and held pressure for over a week. I would imagine that the fan could theoretically pressurize the system by pushing air back up to the tank, but I would expect that to bleed off when the car wasn't running. My car sat for a week, then suddenly dumped 3 gallons of gas 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.......

The first pic shows how I hooked it up at first

The second is from PP and is listed as a 76 evap system, shows the fan being hooked up to the opposite sides of the canister. I will use this layout.

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 don't think that is the issue because I THINK that the extreme pressure in the tank is what pushed that much fuel out.... Or, perhaps I have acquired a garage gremlin.... Worse comes to worse I will toss the whole thing and just vent from the expansion chamber. :blink:

Bulldog9 · 12-10-2015, 12:32 PM

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 ful up through the OLD fuel return line. I relpaced 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 pusing a gallon or two of fuel on my floor, there was still enough pressure to make the cap pop up when unscrewed.

Turns out the small vaccum 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 enviornmental weenie, so I may just pull the whole charcoal canister and call it a day....