(Edited 11/11/03)
I found why my gas mileage is so lousy and why it is impossible to lean the mixture enough at idle. The CSV was leaking terribly. I took off the solenoid and gas would run (not drip) out of the hole when the key was on.
(I found later that the fuel tank vent pipe was clogged, and the immense pressure build up on a hot day was forcing fuel past the csv valve.)
I’ll relate my experience in fixing this; perhaps it will save a few hours or dollars for another list member.
The CSV (on my 1965 Euro) has five connections. There is a 12V wire going to the solenoid, often called an “electric magnet.” There is a ground wire (yellow) going to the top solenoid securing screw. There is a fuel line entering from the front. From the rear is a larger pipe, carrying air. Finally, the CSV is connected to the intake manifold.
The fuel line connects to a fitting that, in turn, is screwed into the body of the CSV. This fitting contains a screen (filter), and holds a coil spring that acts to hold the “valve” closed, preventing (hopefully) the flow of fuel into the valve when the solenoid is inactive. Within the CSV is a brass tube that contains a loose-fitting piston-like brass piece (“valve”) with a lip around it. This valve slides in the brass tube while the lip presses against the end of the brass tube, thus sealing off the fuel. The spring presses against the valve, holding it against the tube.
Directly opposed to the valve is a plunger which is part of the solenoid. When electricity is applied to the solenoid, this plunger shoots out and pushes the valve open, against the spring. When the piston is open, fuel flows into the brass tube, is atomized by the air coming in through the air pipe, and then sprayed into the intake manifold. The longer the solenoid is open, the more the fuel that enters to enhance starting. This time is governed by a relay that controls how long the 12V is to be delivered.
It is pretty simple to take apart the CSV and the chances of ruining or damaging the unit are not very great. First, remove the wires to the solenoid and remove the solenoid. I suggest putting the small screw back into the solenoid (12V screw) so it doesn’t get lost. There should be an o-ring between the solenoid and the CSV.
Then loosen the air pipe with a 19mm wrench. Do not bend the air pipe! Then loosen the fuel pipe with a 17mm wrench. It is ok to slightly bend the fuel pipe, because it is flexible enough to bend back by hand. Next loosen the fitting between the fuel pipe and the CSV with a 19mm wrench. Do not remove this fitting at this time.
Now remove the CSV using a 5mm Allen hex wrench. A ball-end hex socket works well, but all can be removed with just a regular “L” shaped Allen wrench. Now the CSV can be removed. Again, do not bend the air pipe. It should just fall off when you remove the CSV.
There will be an o-ring between the CSV and the intake manifold. Be sure you don’t let it fall and get lost.
Remove the fitting and clean it out. Carburetor cleaner in a can with a spray tube works very well. Be sure when you remove the fitting that the spring does not go flying.
Now the valve is exposed and can be removed.
It is not possible to look at the valve and the brass tube in which it rides and determine how good the seal is, but if the thing leaks, the seal is not good enough. What you want to do is to lap the two pieces together so they mate perfectly. Any auto parts store will sell you a tube of valve grinding compound for a couple of bucks or euros. This is like toothpaste, a sort of liquid sandpaper. It contains grit suspended in an oil and when parts are rubbed together with this paste between them, a slight amount of material will be removed.
Put a little compound on the valve where it contacts the brass tube. Put the valve back in place and turn it a few times to remove a slight amount of metal from both pieces. I chucked up the valve in my electric drill and turned it that way for a few seconds.
Clean up all parts with the spray carburetor cleaner. The valve grinding compound washes away very easily, but be sure the valve moves easily in the tube.
Reassemble the spring and its holder. Its probably a good idea to slightly stretch the spring to re-establish its tension. Attach the fuel line, but do not mount the CSV onto the manifold. At this time, you can observe the operation of the valve and see if you have stopped the leak. Turn on the ignition key but do not start the car. Full fuel pressure is now being delivered to the brass valve. Push down from the solenoid hole with a nail or something similar to open the valve, and then release it. Fuel should gush out when the valve is depressed and then stop completely when it is released.
Reattach the CSV to the intake manifold with the three Allen screws. Reattach the air pipe and fuel pipe and fitting. Tighten all connections, but not too tight (you're screwing into aluminum with large wrenches). Be absolutely sure you don’t cross-thread anything.
Test the solenoid before reinstalling. Clamp it to metal to ground it (I used a small pair of vise grips to hold it on the throttle shaft plate) and then, holding a wire to the positive battery terminal, touch the other end to the 12V screw. The rod should extend about 3/16 inch.
Remount the solenoid.
To see if all is working well, remove the 7mm screw in the side of the CSV and see if gas comes out when the ignition is turned on and then stops.
