The Stovebolt Site Forums The Shop Area General Truck Talk Vacuum vacuum everywhere...........

I got my '59 Apache running this weekend and realized that I installed the wrong fuel pump. There is an extra vaccum line from the fuel pump through the firewall. I also have the normal one that goes from the carb intake through the fire wall.

Now I know that only the windhield wipers use vaccum. I searched through all my manuals and can't find the reference to dual vaccum anywhere. I am sure you guys must know the answer to this and it would be helpful to locate some schematics for how this is setup.

They most likely join under the dash. The idea of the additional vacuum is to aid wiper performance. If you're never out in the rain and don't need good wipers just cap the line that connected to the fuel pump.

Intake manifold vacuum to one side of the dual-action fuel pump and the other side of the dual-action fuel pump to the vacuum wiper motor.

If your fuel pump is not labeled as to which port goes where, do it one way and check it out and, if that does not work, then do it the other way.

Not sure why you'd have 2 lines through the firewall unless a PO had a vacuum guage installed in the cab. Guess you're going to have to get upside down inside the cab with a flashlight and spend some quality time getting acquainted with what's really going on in there.

Should the vacum created from the dual action fuel pump be adequate for the gear change assist?
Jianis

Jianis, I'm not aware of any factory vacuum gear change assist. It may be after market. Post this question in engine and driveline with more details on it and maybe someone will have heard of one.

I believe the vacuum shift assist was only on the late-40's passenger cars. I've never seen that option on a 1950-up car or any of the trucks.
Jerry

Cletis and Jerry

I had the idea that the 1/2 ton tracks from the 40s had it as the passenger car did .
The truck I am rebuilding at the moment is a 48 Fleetmaster passenger car that was converted to a truck witch had a vacuum shift assist ( that was before it was stolen...)
Thank you

Jianis

Jianis,
I think they discontinued the vacuum assist because it wasn't a good idea. It could be a big headache to maintain.

Let's get back on topic here. Thanks.

My guess is someone replaced the original dual action fuel pump with a single function one. They then plumbed the wipers to the manifold and left the original line in place.