Fuel pump vacuum

[Deleted User]

I'm going to use the vacuum line off the fuel pump to a vacuum tank to run my windshield wipers. The problem is the actual line on top of the pump is missing and the port isn't threaded. Was that line just pressed in? I'm thinking of a drop of liquid solder on the correct size tubing should keep things in place. Steel line of the proper, I think 3/16 tubing seems correct. Does anyone know for sure what size the line is?



Harry

mars55

Well, it would help if you give the make of the fuel pump and the model number if you can find it because on the stock AC Dual Action pump all the connections were threaded.

Unknown

Harry, you sure you have a dual action pump? They have 2 diaphragms, one for fuel-one for vacume, ---Tech question for all. Why the tank ? All I ever saw for wipers was direct to the wiper motor . Another "Q" will the pump provide more/stronger vacume than the intake manifold ?

Edwardjohnsr

Harry:

I have two fuel pumps (one is a core) and the vacuum line from the pump to the windshield wiper motor is "not" threaded on either one. I have had the same problem of the line pulling out and have not yet gotten a good solution to the problem. I hope someone can advise.



Regarding the use of a vacuum tank, I don't know why this is needed if you have the combination fuel and vacuum pump. The vacuum pump is there to provide added vacuum when the manifold vacuum drops too low. The vacuum tank was usually used when there was a single action fuel pump that did not have the secondary vacuum boosting pump.



Good luck,

Ed

[Deleted User]

Okay guys, thanks for the replies, Mars55 stock dual action pump, original equipment.



37 T, all holes threaded except the vacuum line. I know, when I had the pump off I was going to put a new line in, since there were no threads I put a wood plug in so as not to have a vacuum leak.



Ed, I have never had a car with a vacuum line off the fuel pump before so I was going to go the vacuum tank route so as not to suffer from wiper speed loss during acceleration. I guess that isn't an issue when you come off the pump. I will install a vacuum line and run direct, I'll let you know how it works out.



Harry

Park_W

Harry, I'm running just the vacuum boost fuel pump on my Hornet, and though the wipers run a bit slower with wide open throttle (steep hill or a passing situation), they still run well enough at those times. I never saw a vacuum boost pump with the vacuum line ports unthreaded, but from the posts here it seems some of them were made that way. If the vac line hole isn't too big, I assume one could tap it for 1/8" pipe thread, which is the way most pumps are made. You may want to test the performance of the vacuum pump with a gauge while you're at it ... at rpm of 1,000 or so, it's supposed to generate about 12 in. vacuum. That's with gauge on the wiper motor side, and the other side "open" (not connected to intake manifold).

[Deleted User]

Park, I thought the vacuum was coming off the manifold. Does the top of the pump create vacuum in the pumping action? I hate to tap into pot metal which is what the fuel pump seems to be made of. I was thinking a close fitting piece of tubing with an epoxy seal.



Harry

Unknown

Harry, think I'd try some permanent type LOCKTITE { need heat to release it } or LOCKTITE BEARING SET, along with the close fit tubeing,should have to tap it in with light whacks. I'm not in favor of tapping threads either. Bud

mars55

Harry



Does your fuel pump look like this.







Here is a diagram of an AC pump. Notice that the vacuum pump connections are threaded.

[Deleted User]

Mars, yeah, maybe, it's hard to tell in the dark with a flashlight if it looks exactly like that. It doesn't matter how many drawings you show me though it isn't going to put threads in the draw side of the pump. That hole is smooth and untapped. Did you know the pump in the drawing is upside down?



Harry

Walt-LA

Lower sketch (diagram) looks like a single action pump. Would be pretty hard to run it if the gas filter bowl shown in the in the sketch were turned over....



Went out and looked at mine which is a dual action pump. It corresponds to to the photo/diagram labelled "AJ." There are two separate operations with this pump. The bottom chambers pump gasoline only. The top chamber is connected to the intake manifold just below the carburetor by a line connecting to the pump on the front (towards radiator). The second line is opposite, and in my set-up is connected directly to the windshield wiper motor by a rubber hose.



All ports are threaded.



I bought a Trico vacuum can some time back with the idea of using it as a reserve for hills. It is large, and has a built in check valve, but decided was not necessary, though can still stall/slow the wipers on a good hill. But then have not rebuilt wiper motor, just cleaned out the "cobwebs."



Walt-LA

[Deleted User]

Let me describe the fuel pump, it is a dual action pump, no filters on it, the bottom part of the pump handles the fuel, draws in from the back of the pump, exits the front to the carbs, top part of the pump has four ports, two marked "out" on the side furthest from the block, the outer forward port is connected to the intake manifold and is marked "out". The two inner ports are marked "in", they are closest to the block. The back "in" port I had to plug with a wood dowel as it was pulling vacuum. That is the port that I will hook the wipers to. It is not threaded. One "in" port and one "out" are open to atmosphere but not creating and vacuum or pressure. Without pulling the pump I can probably not tell what make it is but I will get in there with a mirror and see if I can make out the brand. I think I'll go out and pull the dowel and hook up the wipers.



Harry

[Deleted User]

Seems to me that in '54 pumps were made with pressed in fitting. Locktight would hold it in forever.