Hello,

My orion is fitted with twin 40 DCOM Weber carbs. It has a facet electric fuel pump and a filter king (filter and regulator). Everything uses AN -6 fittings. The carbs have been correctly set up and rolling road tuned and the fuel pressure is 2.5psi

The flow of the fuel is (in the boot) from the tank to a filter, to the pump, to the regulator, to another filter, (in the engine bay) to the right carb, to the left carb. It is then dead-ended at the left carb.

I had these carbs rebuilt and it was running perfectly. However, after a long cold start attempt from not being started for 3 months, fuel started leaking out of the bottom of the left carb (from where the diaphragm is).

It would appear that when priming the pump for a while the fuel pressure built up was enough to override the floats and allow more fuel back in the carb. As the regulator is set to 2.5psi, why did this happen?

It worries me that there is nowhere for the fuel to go if the pump continues to pump after the float chambers are full if the car does not start.

Therefore, I am wondering if I put a return after the last carb (as a sort of fail safe), then would I still have significant fuel pressure for both carbs?

My current setup also has a return with a 1.5mm restrictor before the regulator, back to the tank so that excess fuel that the regulator denies has somewhere to go. However, this did not protect against the problem.

I am playing with the idea of having a shut off value after the last carb so that I can open it and have the excess fuel go back to the tank when the pump may be running for without the engine running (when priming).

So, to summarise, I know everybody appears to dead-head twin carb setups, but will it do any real harm to have a return after the last carb in extremis?