So I've found a rebuilt fuel pump so I'm converting the car back to a mechanical fuel pump from electric for the sake of reliability.

My dumb question:

There's an inlet and an outlet at the bottom of the pump, and an outlet and a vacuum port at the top.

Where does the vacuum out connect to? It's not clear from reading the '61 manual.

ALSO...

Is there any harm in leaving the electric fuel pump inline? It's right by the tank. I figure at some point I could hook it up to a switch inside the car and use it to prime the carb.

 

I am not a 394 expert, but I believe that the vacuum was to run the vacuum wiper motor.

It is completely fine to leave an electric fuel pump inline - your mechanical pump should have no problem pulling fuel right through it, and, as you say, it could be useful in priming the carburetor after extended layups.

- Eric

 

The vacuum port operates your summer ventilation and heater vents. You run a vacuum line up under the dash. My 61-62 showed diagrams of it. Do a search on this site, some of guys helped me figure it out.

 

61-62 service manuals-sorry

 

61 and 62s have electric wipers.

 

I believe the 62 full size has a vacuum reservoir between the firewall and the driver side inner fender? It was several years ago but I believe that was how our 62 Dynamic 88 was. After that it went to the interior.

 

Thanks for your help, guys. Looks like I have found a thread that explains the vacuum routing from the fuel pump.

https://classicoldsmobile.com/forums...line-help.html

 

Yep that's the thread. Once you run the vacuum line into the firewall you should a plastic T it connects too. The rest is a challenge!

 

The schematic diagram for the vacuum routing from the fuel pump to under the dash heating and ventilation system (Deluxe Heater only or with A/C) is on page 467 section 16-15 of the 1961 service manual. Original vacuum hoses have colored stripes painted on them. If all you need to do is connect the fuel pump to the black tee between the #4 port on the ventilation/A/C side and the #3 port on the Heater control it should simple to find.
If there are hoses disconnected from the controls this can be a pain. Place a piece of masking tape on each hose and write the number of the corresponding port on tape. Use a different color marker for each control side. Very tight up in there and hard to see. If you do not want to remove the control heads, you will need some small mirrors to see the numbers for the ports. Hope this helps.

 

 

As to the second part of Post # 1 ,no there is no harm in leaving the electric pump connected ,but I would put a separate switch inside the car and turn if off when the mechanical pump was working well. If your car sits for very long and the gas drains back making it hard to start,just turn the switch on to the electric until it quits clicking and your gas will be at the carb and ready to start.
It also makes a good "Backup Pump" to get you home if the mechanical pump was to fail.
Larry

 

that's the way I have mine set up , worked out well when I had to rebuild the mechanical pump , plus it does make it easer to start after siting for some time ,