single or dual action fuel pump?

ok, went to go order a fuel pump for a 268 Pontiac Straight 8... and it asks if it's single or dual action? how do you tell?

Thanks,
Bobby

 

Dual action has a vacuum diaphram to run the wipers. Single action is just a fuel pump.

 

badshifter is correct - as usual. Look at your old one...if it has two diaphragms (usually stacked a couple of inches apart) - one is the fuel pump, the other powers the wipers.

 

dual action, should've known... I guess I got excited when something came in the shop and the tank didn't have to be dropped to change the pump... so I forgot..

 

now that's a good one

 

I actually looked for a dual action pump for my FE to work with the vacuum wipers. I know the "proper" thing to do is to buy a high volume pump and spend a couple of hundred on an electric wiper kit that I might use 3 times if I live a long time. Besides they look cool IMHO