fuel tank pressure build-up

[moegamat]

Hi all

I have a 1983 vw caddy,..repaired my fuel tank(due to leak)....have major problem with pressure build up now.Have to remove fuel cap regularly to release pressure.....Is tank overfilled?I have checked all pipes for blockage...NO BLOCKAGE.......also, I have discovered that there are three pipes attached from the tank leading towards the engine,..1st for fuel feed,2nd for fuel return..........WHAT"S the 3rd one for?

[moegamat]

just checked,.....behind fuel flap there's some sought of valve,......valve has two connections:1 connection attached to small hose connected to top of fuel tank(above "float"),....other connection is pipe/line leading towards engine bay,........ANY IDEA WHERE THIS IS SUPPOSED TO BE CONNECTED TO?ANYONE?

please reply
Cape Town
South Africa

[rvitko]

It just is inserted into a hole in the frame ahead of the front bumper shock absorber. That valve is probably bad. The test procedure is outlined in the official manual as:

Hose connected to bottom nipple from fuel tank is C
Hose connected to top nipple from expansion tank is A (bumper rail)
Middle nipple is not used- B

Connect a hose to each nipple A and C
Place hose A in tank of water
With valve upright A on top, blow through C, high back pressure should be felt and bubbles should be seen in water

Tilt valve 45 degrees. Blow through C. Very High back pressure should be felt and no bubbles should be seen.

Place hose C in water and blow into A with valve upright, low back pressure should be felt and bubbles should be seen in water.

On mine the valve is black on top, grey on the bottom. The manual shows it as all black, but it is in black and white after all.

[moegamat]

thanx for that info,...what I can't understand, is that I have this caddy now for more than two years, without anything attached to this "third" pipe at the front. So you say I should attach the same "valve" setup as that I have at the fuel cap?Is this necessary?
What I also noticed upon removing the fuel tank, is that there's two outlets on the top(@ the float).One of them on my caddy is blocked off.Could someone please be so kind to give me a complete hose connection diagram of the fuel system?

[rvitko]

The bottom hose should go to the fuel tank, the top hose should run all the way to the front and terminate in the frame. That's it. They both meet at that check valve. The third nipple on the valve (middle one) is not used.

[moegamat]

thanx so much rvitko,...gonna try it this morn., which country You from?.....was checking out some of the other member's caddy's on this site.....WICKED MAN......by the way, any advice on a cheap way to upgrade the braking system?My caddy has a set of 205/40/17's,...and boy how hard to stop ,especially when loaded.Also, does anyone of you also experience heavy wind noise?,especially at hi-speed?I have many tedious problems also to sought out,you know these old vehicles comes with rattles and nerve-recking noises,eg. problematic gear selection,noisy dash,hard ride,stiff steering,squeeky blade springs etc.etc.etc.,Gonna try to post some pictures of my caddy little later,.......thanx again for any advice.

Moegamat
Cape Town

[rvitko]

I am from Texas. I completely tore mine apart. For the brakes I used Brembo cross drilled rotors. Stainless steel braided hoses, ATE Super Blue Racing Fluid, Eurosport drums, the shoes i got are from Australia and they have a red backing plate, they appear to be ceramic but I forgot the make. The pads for the rotors are semi metallic, some fancy brand I also forgot. I just asked Elite Auto in Canada to set me up with a full set. I also changed the master cylinder and found my hydraulic booster had failed so I replaced that, I changed the calipers and cylinders too. I plan to use 15" wheels with Conti 4*4 Contact 185/65/15 tires. Here are some pics of my progress Yesterday I sprayed the bedliner and installed the tail gate hardware, rear bumper and tail lights. Today I hope to get the front bumper and some more trim installed and maybe my propane tank as I will have a 1.6l TD and add Propane injection. You can see I added a couple inches of lift.

http://homepage.mac.com/rogervitko/PhotoAlbum12.html

[Darth Garry]

The mystery third hose, is I believe a vent. If it's plugged somewhere along the line, that's why you'd be building up pressure. It doesen't connect to anything in the front, just goes into the frame, as it's relatively clean in there so dirt won't get sucked back into your fuel tank.

Garry

[veedubbleya]

Can anyone from the UK confirm if this is the setup for UK Caddy's

Just wondering if we have that vent? :i_dont_kn if not what do we have?

I'm pondering charcoal cannister, and evaporative emissions at the moment.

Use it or lose it? (swap from cabby to caddy) :td :tb

Don't think it is required in the Digi 2 setup......more a tree hugging, peace loving, kind of thing to do...:comfort:

[moosecaddy]

I think they all have the canister, on my caddy its behind the fuel filler plastic cover (situated actually inside the the outer skin) see pic below.

My jetta 1.3 has one..as does my golf gti.

[veedubbleya]

Cheers Moose :)

[Al]

The UK Caddy has effectivey 2 vents

1. overspill for the filler neck.

2. Air vent built into the tank sender, this feeds to the filter moose shows in his pic and the other side vents to the ground (this pipe comes out of the same rubber grommet as the actual tank filler when you look underneath :)

You dont need a carbon canister for any conversion, like you say thats just for saving the planet lolol

[veedubbleya]

You dont need a carbon canister for any conversion, like you say thats just for saving the planet lolol

Cheers for the definitive:thumbs_up

I have my own views on saving the planet, and its not using the motorist as a cash cow, whilst cows fart tax free. :)