fuel line check valves

I am going to change the supply fuel line check valve on my 96 B4. Do I need any special tools to get the old one off? A couple of pliers for keeping fuel from draining out from either direction?

You will need something to cut the hose clamps off and then some mild heat to soften the lines to pull them off the check valve barbs. There is no way to prevent the fuel from draining back into the tank, so just prime the IP when you're done. Then you will need new clamps, I recommend new stainless crimp clamps, which can be found at most marine stores.

Abacus said:

There is no way to prevent the fuel from draining back into the tank, so just prime the IP when you're done.

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Wait what? Are you saying that they don't work? Cant you make or get a spring loaded check valve? I use them on my water meth injection to prevent back flow and to break the siphon effect when its not on.

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Mongler98 said:

Wait what? Are you saying that they don't work? Cant you make or get a spring loaded check valve? I use them on my water meth injection to prevent back flow and to break the siphon effect when its not on.

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As soon as you remove the supply check valve, the fuel in that line between the check valve and the tank is going to drain back into the tank. It's simple physics.

And I never said they didn't work, where did you get that from?

And yes, he or anyone can make a spring loaded check valve, but that was not what he asked and how would you remove the original and replace it without the fuel draining back?

You cannot pinch those fuel lines since they are rigid plastic on one side and the other is too close to pinch, so the check valve must be removed.

I was confused. If you take the hose off to take the check valve off and replace it, it would not drain back into the tank, but rather into what ever catch basin you have to catch all that fuel siphoning back from the filter and the entire line. When you said " back into the tank" i got confused. Not sure hot taking a hose off puts it back into the tank without reconnecting it. Sorry, i see what your saying but it did not make logical sense the way you said that bit. Also it was so simple and obvious that i read into it too much.

Mongler98 said:

I was confused. If you take the hose off to take the check valve off and replace it, it would not drain back into the tank, but rather into what ever catch basin you have to catch all that fuel siphoning back from the filter and the entire line. When you said " back into the tank" i got confused. Not sure hot taking a hose off puts it back into the tank without reconnecting it. Sorry, i see what your saying but it did not make logical sense the way you said that bit. Also it was so simple and obvious that i read into it too much.

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He was talking about what happens after you've removed the one-way valve from the line for replacement, the fuel will want to move back in the direction of the tank.

He didn't mean that it would flow back to the tank once you replaced the valve, but that it would want to flow back while you had the old valve out.

Steve

So the blue one is the return line and the black one is the supply, correct? Is this view in the picture on top of the tank, accessible through a panel under the rear seat?

Yes and no. This is what you will see when you remove the cover, not a whole lot of room there.

And yes, if you look closely on the above photo where you can see the check vales clearly (unlike below), you can see the little arrows on each of the check valves denoting their flow path.

Great, I see the arrows on both the line and the check valve, so its pretty clear now. thank you!

I never ended up replacing the check valve, since doing the quantity adjustment and replacing the n75 and multiple vacuum lines fixed the problem. Runs like a top now, thanks to you all!