The Stovebolt Site Forums The Shop Area Engine Shop Let’s talk fuel pumps, dual suckers to be specific

Let’s talk fuel pumps.
I was at a buddy’s house the other day and he had just gotten his new dual action fuel pump delivered. We took it out of the box to look at it and as I remember it, you could bush the arm of the pump in by hand and hear the diaphragm pumping air. This pump arm only moved about an 1/8”. Even when I leaned it against the edge of the work bench and pressed with my body behind it, it still only moves a small amount.
When I got home I took the dual action that I got form Chevy Duty last year off the shelf and it is the same way, the arm only moves a small amount.
I don’t have any single action pumps around to compare them to but they have to have more movement to do any sort of pumping I’m sure.
Anybody run into this before?
Denny Graham
Sandwich, IL

why do they "have to"? the arm is a lever, which can multiply the travel beyond the pivot, the diaphragm can't move far [look at the depth of the pump body] and the actuator arm is basicly run by a cam lobe with little lift, maybe 1/4" ... and isn't the dual action pump working when moving both directions? that should mean it only has to move half as far for the same amount of work .... besides, I just checked an old regular pump - moves about 1/4", once the slack is out

Bill

Let me re-adjust the movement, Bill, it's more like a 1/16". I think you got the lever arm leverage backwards. The fulcrum is closest to the diaphragm so the lever would have to move a good distance to move the diaphragm a small amount.
Something isn't right on these pumps, they are made in Canada.
Denny G

there's the reason, Canadians are more thrifty, don't need to pump as much

is the kind of pump you mean? I did an actual measurement, both pump arms move exactly 1/4" to bottom after the slack is taken up .... the dual one doesn't make the suck sound, so who knows the condition, the regular one sounds fine

if you think about the 'knob' on the bottom of the regular pump and the distance between the 2 heads on the dual one, I'd say the arm inside the pump is longer than what's outside where the pivot is

thought I'd open it up and see - put it back together and it sucks and blows now not much room to move in there, and the inside throw has to be more than outside .... also it has an AC tag on it, #9033 I think it was

Bill

yep, that's the one Bill, my buddy's is without the glass bowl, mine has the glass bowl. I see where the ratio is almost 1:1 just a little in favor of the fulcrum to diaphragm. If the arm moved a 1/4" where it contacted the cam lob I would have no problem, but it just taint moving in either one. I'm a little afriad to install either one for fear of braking something inside of a $100 new fuel pump.
I don't think I'm getting anywhere on this one Bill, there has to be something wrong with these pumps.
DG

maybe old stock that's "stiffened up"? [doubt they're big sellers!] .... have you opened one? the single action pump here didn't push much at first and didn't make a sound - I banged the push arm down on the bench and it smartened right up, moved well and sounded good - the double one came apart easily and worked fine once back together

I just can't see that diaphragm with maybe half inch around the center metal plate moving much at best, might just be too stiff for manual movement .... but I'd be reluctent to use it too without hearing the nice squishy sound first

Bill

I wouldn't be installing it either, for the sake of the motor. You can always take back a bad part but the damage to your motor is a different thing.

Both these pumps I'm talking about are brand new in the box Bill, so you can understand why I'm a little reluctant to start tearing them apart. I bought mine last year Fred so I doubt it if the vendor would take it back now. I don't think I could find the reciept now or if I'm know for sure who the vendor was.
One thing for sure, I taint gonna be needing it anytime in the future. The old gal is dang near bare from the cowl forward, and all because I wanted to change the bumper. I'm pretty much down for the winter and probably then some.
DG

Denny!! you think it's unsafe to use, you can't send it back, you're afraid to open it up ..... gonna need it to keep a shelf board from blowing away? back in the day they sold repair kits for fuel pumps, nobody bought new ones if they had an old one to fix

one bolt on each end, 8 screws for each side, diaphragms just pull out and push back in, 5 min job max - there's nothing inside to break, even the old cork gasket on my used one came off clean, if you can't take it apart and reassemble it without any problems at all I'm ready to start dis-believing all the picky scratch rebuilding you're always on about

Bill

Now there you go exposin' my secrets Bill, all those pictures that I've been posting the last three years were my evil twin's work. I don't like getting my hands dirty you know!
Well anyway, I ate a big lunch today and this time I really put my big old stomach into it, it moves!!! Man is that spring stiff, I find it hard to believe that isn't gonna wear the lobe on the cam out in record time. Did my buddy's and it's the same way, ya just gotta really lean into it, I'll bet there's a hundred lbs of spring pressure on that lever. So I can get it to move about a 1/4" to 3/8" that's more like it. Not having a cam handy, I'm not sure what the lift is on the fuel pump arm.
So all's well in Graham's Garage tonight.
Thanks guys,
Denny Graham
Sandwich, IL

Hi -

I am in the process of re-assemblying the 261 Stovebolt in my '49 Chevy 3600 pick-up. I am going for that "old school" look and want a new fuel pump with the glass bowl. Does anyone know where I can get one new? Any other suggestions?

Thanks!
Dan Michalak
Omaha, Nebraska

try here, 10% off for stovebolters

Bill

to help stop wiper slow down?
clue me. why would the fuel pump affect vacuum?

the glass bowl has no effect on wipers, but the dual action pump has a vacuum boost side for the wipers

Bill

glass bowl has no effect - right. i didn't know duals existed, ergo, that the duals had vac assist. so, if i'm remembering correctly from my '50 in '73, upon acceleration, vac changes and slows the wipers down. so, with a dual, it adds vac so that the wipers don't slow down upon acceleration?

The dual action pump is actuall two diaphagm pumps in one housing. the top pump pumps fuel to the carburestor and the lower pump only supplies vaccum to the vacuum wiper circuit. Therefore when you open the throttle which causes the vacuum to drop in the manifold, because the induction system is essentually open to atmosphere, a vacuum source is still avalable to the wipers.
DG

a-ha - thanks for the expla

back in the day they sold repair kits - red, the link that you posted to the company that sells pumps also sells a rebuild kit