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Dual Fuel Pump Plumbing Schematic???
Ok, I’m throwin’ in the towel, I give up. Been looking for a few days and again for the last couple of hours for anything that shows the vacuum line connections and routing for the dual fuel pumps. I’d swear that Timothy at the Stovebolt had directed me to that info a while back but I just can’t seem to find it. Might have been Gene over at the VCCA chatter but I never was very good at organizing my references. Heck, talk about disorganized, I worked with all my tools in a pile at the end of the work bench my whole adult life. My wife heard me cussin’ bout not being able to fine anything and she made me go out and buy a toolbox this summer.
Well anyway, my buddy wants to get his 1950, 216 running before the snow sets in so he can move things around in the garage. He decided to put a dual fuel pump on instead of the old single and I told him I’d help him.
I’ve looked thru every GM manual, document, bulletin, paper, etc., that I have for a schematic and nota. Anybody want ta help the old man out here, please????
Denny Graham
Sandwich, IL

Also, What could you do if you didn't want to hook up the vacuum section at this time? Thought about a couple of 1/8"-npt x 1/4" hose barbs and a hose connecting the outlet into the inlet or visy versy.

The wiring(?) of the dual fuel pump is very straight forward. The section of the pump used for the fuel should connect to the current lines without modification. The vacuum booster section is wired(?) with the line coming from the base of the carburetor to the inlet of the vacuum pump. The output(?) goes directly to the vacuum wiper. You can identify the inlet and outlet by placing a finger over the two vacuum fittings and find the one that is producing vacuum with the engine running. You could also determine the correct connection by operating the plunger with the pump off the car.

I would think this is all laid out in the repair manual.

Aw shucks Ray, give me a little liberty with the schematic thing will ya. I know the fuel pump is plumbed into the fuel system, duh………I thought I saw a drawing in one of the manuals of the way the lines were routed but that’s what I can’t seem to find. If I remember correctly the one side of the vacuum section was routed it a fitting on the intake manifold where the wiper motor is normally connected. Tim L. over at the Bolt also thinks that was correct.
I’m sure I’ve seen something that the dealer’s service department had on the dual stage pump installation. I’ve looked thru the Truck Shop Manual and the Factory Assembly Manuals and the Service Bulletins and the Engineering Features. I think it might have been RPO “340A Fuel & Vacuum Pump Booster” that I saw but can’t find that anywhere either.
DG

Oh by the way Ray, from the dictionary,
sche·mat·ic (ska -mat ik, ski -mat ik)

adj. Of, relating to, or in the form of a scheme or diagram.

n. A structural or procedural diagram, especially of an electrical or mechanical system.

sche·mat i·cal·ly adv.

Sorry Denny, I thought you had a sense of humor. Good by!

Did I come off that way AGAIN! I do, I do have a sense of humor, I'm mostly Irish, gotta be able to take a joke if your Irish. I thought we was still kibitzing Ray, just thought you might have been stuck down there in the basement at the radio bench to long and needed to get exposed to something new.

So looks like I'm just gonna wing it. The part that I'm not sure about is where and how to terminate the vacuum line when it transitions over to the rubber......
I the line goes directly to the wiper then there must have been a bracket of sorts to mount the line to the manifold or carb? Also I thought the pump was an assist to the engine vacuum so I was always under the impression that the manifold fitting was changed to a 'T' and that was where the vacuum line from the pump went to.
See, nothing is as simple as 123 is it.
Denny Graham
Sandwich, IL

Ray and Denny.

You both have great humor!! Love reading your posts.

Am confused about the vaccum line going from base of carb to the inlet side of pump? It, would lead me to believe, that than there would be no vaccum to distr?? Perhaps Ray could clarify that.

I would think that the pump would be routed from the single manifold connection to the inlet side of pump and from there the outlet side directly to vaccum wipers??

Just curious, Denny, please let us know how this project turns out if you would please?

Jim.

I have the dual action fuel pump on my '51 Chevy, and the vacuum port on the carburetor goes to the vacuum advance on the distributor.

Just a case of fingers and thought not coordinated. I meant to say at the wiper connection on the intake manifold. Sorry about the confusion.

Some time ago I had a question about the plumbing of the dual action AC fuel pump. Here is how I saw a factory equipped 54 Chevrolet car plumbed:
The small vacuum line at the base of the carb. goes to the vacuum advance. This vacuum port is on the base of the carb and is where the vacuum advance must be supplied.

The vacuum line on the outside port of the intake manifold goes to the VACUUM INLET port of the dual action fuel/vacuum pump. the OUTLET port of the vacuum pump goes to the wiper motor. This allows normal vacuum from the manifold to operate the wiper motor when there is good engine vacuum.... When you are pulling a hill and the engine vacuum is low, the dual action pump goes into action supplying vacuum to the wiper. I believe that the hose from the manifold was connected to a steel pipe behind the valve cover where the vacuum line crosses from the left side of the engine to the right side of the engine.
I have a picture somewhere but I believe that is how it is plumbed. It makes sense when you understand that the engine vacuum is the normal supply to the wipers and the vacuum pump kicks in when there is low engine vacuum, Check out the dual action pump there may be a special check valve type apparatus between the Input and Output ports.

If I didn't want to hook up the vacuum part of the dual action pump I would just use some soft plastic plugs and plug them off,to keep the vacuum part clean, leaving the standard wiper hose from the intake to the wiper motor.

By the way what you are talking about must be for a steam engine a steam-matick , the one that you need is a vacuum-matick ! If you spell worser than I do you are in deep kaka Ha! :vcca:

Don’t mind Mack Jim, he’s just an old retired English teacher, right Mack??????

But yepper, that’s the way I plumbed her in, i.e., 90° elbow at the manifold to the high side of the pump and from the vaccum side ran it just behind the Rochester and rubber hosed it from there. Of course the replacement dual pump has its fittings pointed in some oddball direction especially when you compare it to the illustration in the Factory Assembly Manual, RPO340 section 0, sheet 18.00. Apparently there is no correct routing of the lines, since I haven’t been able to find any other illustration or a picture of a vehicle with it’s original lines in still in place. Heard from a few guys that say they have original factory installed vacuum boost pumps on their cars but it must be to cold to run out to the garage and snap a picture.

Anyway, I runned over Sunday after church and ran the lines for him, ended up looking half-arsed decent and as soon as it warms up I’ll snap a picture of the “plumbers nightmare” in case anyone else ever wants to upgrade and asks the question.
Thanks for the discussion fellers,
Denny Graham
Sandwich, IL

One other thing, have any of you bought brass fittings lately??? Mon have those gone thru the roof or what! To plumb this new fuel/vacuum pump in cost us almost $30 dollars in brass not including the $20 in steel lines.

OUCH and owie owie!!!

Jim.