Hi,
I just replaced the fuel pump on my 2cv with this: https://www.franzose.de/en/Citroen-2CV/ ... /ANR10622/
The car has been unused for the last 3 months, now it ran for the first time since with the new pump. It seems that the whole carb is pressurised, with fuel dripping from jets, accelerator pump etc. even after the engine has stopped and completely flooding the engine... I checked the needle valve and float heights, everything OK there. The needle valve is definitely OK - it holds this pressure in even after disconnecting the fuel hose. It takes about 10-15 seconds of idle to build up such pressure that fuel starts overflowing.
I'm gonna replace it back with my old pump tomorrow and check again. I think the spring which builds pressure in the pump is too strong, forcing fuel in and forcing the valve open. Unless you have any other suggestions, I'm out of ideas, have been working on the 2cv till 22 PM after my day job since monday so I'm a bit tired by now and not very imaginative...and unfortunately I need to have the car running ASAP.
I'll also take the pump apart and see if I can do anything about the spring, maybe shorten it a bit to make it softer.

Hi Saurus,
maximum pressure at 'zero flow' should be 2.5 to 3.0 psi.
If you check and find it to be too high, it's probably easier to reduce the effective 'throw' of the pump lever by adding gaskets to its underside, which should reduce the maximum pressure delivered by the pump.

p.s. Specified stroke of pushrod on a later 602 engine is 2.6mm, so perhaps 0.3mm steps in packing/stroke reduction?

See, now, that's what I'm talking about, I was too tired to think that maybe there's a less invasive way to reduce fuel pressure
I have no means of measuring the actual fuel pressure, but I'll just try 2 thick gaskets first and then maybe grind down a little bit off the bottom of the lever.

the flow/ pump pressure isn't determined by a spring as you say, it is the pushrod coming from your engineblock.

but I think the length of the push pin (or gaskets) doesn't determine the pressure, it does regulate the flow! the bigger the stroke of this pin the more movement of the membran., the more flow.

I don't know if teh pressure wil be less if you change the stroke.

good luck! (and see you in 5 days? )

greetzzzzzz, Rusty

Hi Rusty,
don't know if you've ever taken a pump apart, but if you do, you'll find the the 'push' from the pushrod is converted into a 'pull' on the diaphragm by an L-shaped rocking lever.
That movement increases the volume of the pump chamber, opening the inlet valve and drawing fuel from the tank.
Spring pressure then pushes the diaphragm back, opening the outlet valve and sending fuel towards the carburettor.
The more the spring is compressed, the greater the pressure it creates, as well as shifting more fuel, I'd reckon...

I've put in an electric fuel pump lately (in combination with 1-2-Spark) and I'm very happy with it.. If standing still for a week or 2 it will pump the fuel and start 1. turn at the key....

It is even cheaper (yes I'm Dutch) then an original fuel pump...

are your floats ok?

Two 1mm thick gaskets solved the issue. Thanks Ken! Compressed probably more like 1 mm together. I couldn't borrow a suitable kit for measuring fuel pressure, and didn't have time to try multiple thicknesses, I figured either 2 thick gaskets work or back to the old pump.
@Rusty: definitely, I'll arrive at wednesday around 8 PM.