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Mon Apr 09, 2012 10:45 am

I have a 1972 Autostick that works great. The only issue I have is that I am having is that it appears I have a part on the engine that can not be identfied by anyone. It starts from the fuel filter bottom then runs to this part that is round with two inlet tubes on top and two on the bottom. From the part, the gas lines go to the carb. I have explained the part to JBugs in CA and they said to take the part out and to only run fuel lines from the fuel filter to the carb and from the fuel line running through the body to the carb. Has anyone ever heard of such a part? It is made in Germany and it looks OEM. Any idea would be great.

Mon Apr 09, 2012 11:05 am

I actually don't believe you are explaining it correctly. When you say fuel filter are you referring to the little plastic filter between the fuel pump and the carb? I bet you are looking at a throttle positioner and those lines you are referring to as fuel lines are actually vacuum lines.

For your car, there is a single fuel line that runs from the gas tank, through the body, through the motor tin and plugs into the fuel >pump<. From the fuel pump there is a single line that runs from the fuel pump to the carb [toward the back and top of the carb]. Often folks put small filters between the pump and the carb, or sometimes folks place it before the fuel pump.These filters are usually plastic but sometimes look like a small metal canister with and inlet on one end, and an outlet on the other. It's wise to move filters out of the engine compartment and above the transmission, or below the tank to help prevent engine fires.

If you post a picture and you'll get your answer.

-jeffrey

Mon Apr 09, 2012 11:26 am

If it's not a throttle positioner, maybe a previous owner replaced the fuel pump with and electric fuel pump and the thing you are referring to is a pressure regulator. However that doesn't explain the multiple lines going in and going out of it.

To post a picture, upload it to the Samba Gallery. Once you upload it, you will see code above the newly uploaded picture that you can copy and paste into a post. Do this and folks will be able to respond better to your question.

-jeffrey

Mon Apr 09, 2012 11:40 am

OK let me try again. I have a little plastic fuel filter and a fuel pump that is NOT electronic. I will start from the fuel line that goes through the car. It goes through the pan, into the engine compartment and into the bottom part of this little doohickey's inlet. The bottom outlet goes to the fuel pump bottom inlet then the bottom fuel pump outlet goes to the carb. The plastic fuel filter bottom outlet goes the top doohickey's top inlet and the top outlet goes to the fuel pumps top inlet and the fuel pumps top outlet goes to the carb, I think. I will post a picture as soon as I remove it from the car, again. I appreciate you trying to help and I will send pictures to better describe this part.

Mon Apr 09, 2012 12:10 pm

Don't remove it, just shoot a picture.

-jeffrey

Mon Apr 09, 2012 1:09 pm

400 million camera's, and you have none and can not get one from a kid?
really?

one famous guy said it was worth a 1000s words.
i think he was underselling the idea.

Mon Apr 09, 2012 1:33 pm

Is it by chance # 1 in this pic? anti syphon valve

Mon Apr 09, 2012 1:44 pm

Wow, I bet that's it. I found a pic. Is this it?

-jeffrey

Tue Apr 10, 2012 3:24 am

BINGO, that would be the culprit. Sorry I didn't get a picture sooner, work gets in the way. Should I remove the thing entirely and just go straight to the fuel pump?

Tue Apr 10, 2012 3:52 am

I don't think it'll hurt but like my pop always sez "if it ain't broke, don't fix it." I say clean it up, move that plastic filter out of the engine compartment, and run with it. It'll give you something to talk about when folks scratch their head trying to figure out what the hel it is.

-jeffrey

Tue Apr 10, 2012 6:32 am

ANTI-Siphon Valves, yes, they to can fail , just like all things....

maybe it is broke, did you test it?, do a leak down test on it?
check the valves.. etc?

the vw does have some unique features, some like motorcycles.
My CB750 cant run fuel until vacuum happens.
on the VW (like a MC):
the fuel runs down hill. or at the LEAST, can siphon at the drop of a hat.

today's cars the consider upside down (my Mx5 as upside-down fuel cut)
some fords have collision valves, that kills fuel with radical stops.

this device, i believe, is so that if you park car
and the tank is full, and the nose is way up high (like in SF) {worst case}

now the engineer , considers some fails. WHAT IF , protections...
carb float stuck open (1 tiny bit of dirt in the float valve?)
or a crack in the fuel pump diaphragm.? oops fuel all over top of hot engine...
fuel lines crack.
fall off. some dork used wrong size rubber (syn) .3" ID lines. (7mm)
what happens is BOOM.

the carb and old mech fuel pumps are problematic devices.
(see those burn marks, on the tail hatches? , not all fires are from bad fuel lines)
I have a death trap fuel pump (VW clone ) on my bench. with side vents.
amazing device, it ejects fuel to the distributor, wow (with acracked diaphragm)
My motor cycle MC , has rubber tubes that guide stuck float valves
to the earth, if you ride alot, you learn this fast. (cut fuel cock !)

You don't want fuel flowing , after you stop a hot engine, this is bad.
also...
and electric pump and a regulator under the tank may also stop
fuel from siphoning. (consider this, at rebuild time)

most uscg approved boats have this device too. so the bilge dont get full of fuel and BOOM.
in the case of VW, it's usually just the bug dies and not the whole marina.

may users just defeat it. sad to say.

fyi , full info

http://www.mvfri.org/Contracts/Final%20Reports/R06-20%20Antisiphon.pdf

btw , one MC i have , if you run it out of fuel
it takes a vacuum hand pump to get the fuel valve back on.

Tue Apr 10, 2012 6:48 am

the device in photo circle #1
only opens with fuel pressure on the top.
so it must be primed.
im sure the Bentleys covers that. did you look?

it does have a diaphram and the diaphram moves down
this moving down opens the normally closed valve (antisiphone feature)
it is a chicken and egg device.

it can fail 2 ways.
bad diaphram (do a leak down test with the top nipple (1) blocked with finger.
the diaphram if cracked will cause air leaks (seems like , vapor lock but is not)

or the valve packs with crap.

but do RTM. my comments are generic to all systems.
i never work manual free , nor should you , imo.

Tue Apr 10, 2012 6:52 am

lets take an opinion poll (is the world safe for democracy?)

i have this safety device. (bad , and proven by simple tests)
should I ? ?
bypass it
or
replace it

I'd bet there is only one answer.?

if you park in a garage with a gas water heater , you might want to
think that through. :evil:

Tue Apr 10, 2012 7:10 am

I've only seen them on a small fraction of a percent of cars I ever worked on. Don't recall any autosticks with a valve like this, but I haven't worked on more than a half dozen or so.

It's a great idea as one poster above mentioned - when parked uphill with a full tank - but, as I understand, it is a two-way street. It should also keep from draining the fuel from the fuel line to the carb and filter back into the fuel pump. From there, the fuel could end up getting back into the case by running back through the pump.

Tue Apr 10, 2012 12:38 pm

So the question remains: I was told I should remove it but if I test it and it does not appear to work, I will remove it. I could also have a bad fuel pump which is $23 so not much of an investment there.

Tue Apr 10, 2012 2:16 pm

yes,
if you do the consensus test, on 100 forums
1/2 say fix it
the other say bypass it. (same on the boat forums,etc)

but not one ASE guy telling you that.

Tue Apr 10, 2012 2:54 pm

I thought the fuel pump that was used with the anti siphon valve was different and if you change the pump to a new style you could then remove the anti siphon valve.

Wed Apr 11, 2012 10:48 am

Thank you everyone that posted a response, I really appreciate it. Does the last post speak any truth? Will a new fuel pump allow me to remove the anti syphon valve? The current fuel pump is the 72' OEM part so most likely it is not working even though the car only has 50k original mile on it. I am going to remove it this weekend to see which pump I need to order so I am hoping that fixes any issues I might have.

Wed Apr 11, 2012 5:57 pm

I searched last night and wasn't able to find anything on that. I don't know for sure, hope someone has the answer. Good luck.

Wed Apr 11, 2012 6:14 pm

I'd remove it, it's only a potential weak link if it obstructs the fuel flow in anyway and the less fuel line connections next to the coil and distributor the better.
99.9% of VWs world wide don't have them and function fine.
It's only an anti drain back device similar to whats used on modern car windscreen washer hoses just to keep some fluid in the lines.

JSalzillo wrote: The current fuel pump is the 72' OEM part so most likely it is not working even though the car only has 50k original mile on it.

Mileage is only partially relevant, the diaphragm in the pump doesn't last for ever and eventually starts to break down but if it is truly the original 72 pump, they are the old rebuildable type