The Stovebolt Site Forums The Shop Area General Truck Talk dual- action fuel pump, need vac schematic

All the best to you and yours! Please don't start the "... break down and buy an electric wiper motor." I'm way too cheap for that, besides I like the challenge of vacuum wipers.

I've done a search for dual action here and have read things like, "...input goes to wiper motor, output goes to manifold." Doesn't make sense to me that if you run a line straight off the intake manifold your wipers run, this is just the opposite of the advice.

Anyone have a hook-up schematic out there? Thanks, Cosmo.

They will indeed run off the engine vacuum by hooking the line straight to the intake manifold.

My 58 Chevy is this way. Only time it gets to be a problem is if you pull a steep hill.

Course with the 261 it has to be quite a hill before they slow very much.

Cosmo,

I think a schematic would be of little help because it seems that dual-action fuel pumps have different labels (and sometimes no labels) for the two vacuum ports. I have seen ports labelled: Input and Output; Wiper and Manifold; and, no labels (and, even Port 1 & Port 2, I think).

Input: might mean "input" of vacuum from the vacuum port on the manifold
Manifold: means to connect to the vacuum port on the intake maifold

Output: might mean "output" of vacuum to the wiper motor
Wiper: means to connect to the wiper motor

On a dual-action pump that was unlabelled, I used short lengths of rubber hoses to connect from home-made "stubs" on the vacuum ports on the fuel pump to the manifold and the wiper lines. There are only two possibilities.

Oh yes, another possibility: a few months ago someone asked the same question and eventually found out that the vacuum side of the dual action pump was not working.

One thing that stumped me when I asked your question a few years ago was instructions that someone posted that described the port "near the block" and the "port away from the block" as being to the manifold or to the wiper motor. I think that different versions/models/manufacturers of the dual-action fuel pumps might have put the ports in different locations on the pump (also, it looks like some pumps have the vacuum side on top and other pumps have the vacuum side on the bottom).

Thus, as stated when I started this ramble, s schematic might not be that helpful. The diagram in the factory assembly manual is not helpful, either. With the three pumps that I have installed, two were oddly labelled or unlabelled; the trial-and-error method worked both times.

In these photos, the "outboard" port goes to the manifold and the "inboard" port goes to the wiper motor.
Dual-Action Fuel-Pump photo 1
Dual-Action Fuel-Pump photo 2

Tim

Cosmo - there's some help in the 55-59 assembly manual - it's RPO 340 - if you've got the same pump, the vacuum connections [lower portion of pump] are labeled:
one closest to bottom of pump, and toward outside is called "manifold to pump assembly"
other, slightly higher and toward engine is called "pump to windshield wiper pipe assembly"
both lines are routed w/ the fuel line up and over the front of the valve cover
the manifold one elbows into the manifold right below the carb where the regular wiper connection is

hope that helps!

oh-oh - Tim's set up is different than shown in the manual, which pictures the pump fittings on the back of the pump, facing firewall - opposite of his - toss yer own coin!
Bill

Thanks y'all. TC, my pump looks like a replica of yours with a few quirks. I think (already knew I guess) that the infamous trial and error method is the way to go.