Fuel Valve Removal

[BeMyWay]

I've noticed that some of you have removed the fuel valve between the fuel pump and carburetor.   

 

I have a 1976 2002...and the valve is working...but I am replacing hoses and cleaning up the engine bay area and think of removing it.

 

Therefore, is there any issues I will create if i remove the valve?

 

Thanks.

[Son of Marty]

Most of the time people removed that valve when they went to the weber carb. If you do remove yours be sure to plug the return line at the tank to prevent future fuel leaks.

[Buckeye]

for most part should not cause any issue by removing fuel return valve. If decided to do so, then install tee fitting between fuel hose coming out of fuel pump to carburetor and then tie existing fuel return line to the tee fitting. 

Now, I would not remove that valve if I was you. In-fact I installed one after I saw your original posting a few months ago if you recall. It make sense to me what is the purpose of it and why was installed by factory in 1st place.

@FunkyLaneO has explained how it works nicely in following link;

 

 

 

[Mark92131]

If you are removing the rest of the smog equipment, I would remove it.  If you aren't, I would pull it, clean it up, replace the lines (gas and vacuum) and re-install it.  The tee fitting is a good idea, otherwise you can run a gas line from the fuel pump directly to the carb, plug the return fuel line at the front of the car (under the battery tray), remove the fuel return valve and cap the vacuum fitting that is connected to the valve.  My Mintgreen 75 had this valve removed by the PO, but he didn't plug the return fuel line.  The first time I filled the tank, I siphoned out about 1 gallon of gas on the floor at the Costco station before I realized what was happening.  I pounded a golf tee into the metal return line with a rock and drove home while praying it would hold.

 

Mark92131

[johninsf]

Quick questions; where does the vacuum line from the valve run to? Base of the carb? I'm wanting reinstall the valve but can't remember where the line goes.

 

Thanks!!

[John76]

Goes to the tap on the #1 intake manifold runner, or the front, bottom port on the original Solex 2brl carb.

This is manifold vacuum (not ported).

[johninsf]

Thanks John great info.

 

The manifold is tapped just below the carb but not on the #1 runner and I think this is where the line was hooked up. #4 runner is tapped and the line runs to the distributor. 

 

The old valve flows from the pump to the carb freely without any vacuum, but the return direction is restricted. It seems like this would indicate that the valve is not working correctly right?

 

Thanks again!

[John76]

18 minutes ago, johninsf said:

It seems like this would indicate that the valve is not working correctly right?

 

No, the valve appears to be working as designed.

When it has no vacuum (not connected, or during WOT) the return direction is highly restricted....but not closed completely.

This allows more pressure and flow to the carb during high demands for fuel.

When there is high manifold vacuum (during idle and cruise), the return direction is less restricted (opened more) which reduces the fuel pressure and flow to the carb when it is not needed.

The return direction is never completely closed (as I originally thought). This allows gas to always be flowing back to the tank to help keep it cool and prevent vapor lock. The vacuum just regulates the return flow between a trickle and a gush.

Clever these BMW engineers!

[johninsf]

Thanks again John.

 

My "understanding" of manifold vacuum is clearly inverse to reality. Clever BMW engineers indeed.