Gary,
Seeing that no one has responded up to now, let me comment.
I don t 'know the answer to your question. I have no experience with that type of fuel pump. Double-action I think they're called.
You may have a bad gasket or a crack in the pump's casing. Accordingly, you may want to inspect the pump's casing for a crack. Using a little oil-resistant sealant with the gasket may help also.
Anyway, my suggestion would be to install a regular fuel pump and take the vacuum for the wipers from the intake manifold. This of course will result in a decrease in wiper action than that provided by the double-action pump.
Just an annoyance when you are climbing hills in the rain. Remedy: Let up on the accelerator pedal now and then to help clear the windshield momentarily. If hard rain is forecast, then leave the car home and find some other mode of travel if you must go somewhere. Don't even use it for an emergency trip to the hospital. Call an ambulance. Getting blood out of the upholstery is hard to do.

If you love

your old car then nothing should interfere with you taking care of it. Driving your old car in the rain is a no-no.

I'd rather die than abuse mine by getting it get wet (except a hand wash job now and then) or have to travel without clearly seeing where I'm going. Would too!.

Of course if yours has been modified or personalized, then have at it without reservation; blood and all.

Best,
Charlie
