The Stovebolt Site Forums The Shop Area Engine Shop Hooking up the double acting fuel pump.

I am getting ready to install my new fuel pump which has the auxiliary vacuum assist for the wipers. It came with no instructions, but after looking at the factory assembly manual, it appears that one line goes from the pump to the manifold vacuum port, and the other line goes from the pump to the wipers.

Does that seem right?

I am planning to make up the lines from some NAPA brake lines. What kind of tool do you folks use to bend the lines?

Thanks,

Kurt

Kurt,

This has been discussed every so often. Sometimes the ports are labeled In and Out. "In" would be a line from the intake manifold and "Out" would be the line to the vacuum wiper. Some are labeled 1 and 2 (or other markings).

Since you have a 50-50 chance of getting it right by guessing (and, at worst you have to check two possibilities), make two "rough lines" (before making final bends) and connect them. If that does not work, switch the connections. When it is right, write down what goes where and finish-bend/cut the lines.

For the temp connections, just use vac tube. Its cheap and handy to have in the shop anyway.

If you are able to work the actuator, you can feel which port draws air or creates a vacuum by putting your finger over the end. You can probably work it by holding the pump and pushing against the work bench. That vacuum port goes to the wipers and the other goes to the manifold. At low RPM and high engine vacuum, the engine vacuum is higher than the pump and it draw through the pump.

I used brake line for my setup. Also, my new pump provided 6.5 psi on the fuel side whereas my old pump pressure was around 3. This caused flooding and I had to adjust the float.

Tim,

The pump I have is labelled "in" and "out" Fuel pump part is also labelled "in" and "out" With "in" being from the tank, so I have made the assumption that "in" would be the manifold and "out" to the wipers. What you say would confirm this.

I tried to detect which port was drawing a vacuum by operating the lever with a finger over each port in turn, and I got no feeling of a vacuum from either port. So I have some concern that it's not working.

What size diameter line did you use? I got 1/4 inch OD tube.


Thanks,

Kurt

I do not recall the outer diameter but I would guess that 1/4" would be OK and it would be easy to find fittings for.

You don't need to worry about the size of the line. I would suggest connecting "in" to the wipers. To me that would be air in and that would be vacuum. On my unit, the in on the fuel and the in for the air are on the same side of the pump, towards the rear of the engine.

Regarding your test, you should be able to feel vacuum on the fuel inlet too, for sure. The lever moves quite a bit and it takes a lot of force to get it to move. That is why I suggested pushing it up against something like a work bench.

Yeah,

I think I was just not pushing hard enough. The old pump moves a lot easier.

Kurt

That is what I found and the fuel pressure was almost twice what I had with the old one.