Slant 6 Fuel Pump Question

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RichardR

RichardR

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Hi,
Just wondering if anyone could tell me what the line from the back of fuel pump to the carb is for? I'm assuming vacuum but for what purpose? and if I get a new pump are the ports in the same location?

thanks :)
 
Fuel pump will have 2 ports: inlet and outlet: one comes from tank, one goes to carb. Does yours have a third? Only thing I can think of vacuum wise (?) would be a Boost referenced line from weep hole to turbocharger outlet. This would provide increased fuel pumping during times of boost, roughly +1 psi per 1lb boost.

housing.jpg
 
So my pump looks exactly like that except on the bridge between the lever side and the saucer side is a big port with a line going from it to the carb.
 
Yeah I think that is what it was called. Is there an electrical throttle kicker mounted to the throttle shaft.
IIRC
the idea was that when you shut the engine off the throttle kicker would de-energize, and close the throttle. This would close that little valve on top of the carb. In turn, the engine-off fuel bowl vapors were routed down into the crankcase and stored there. The next time the engine fired up, those vapors were sucked up by the PCV system. And the throttle-kicker would open that valve to be the bowl vent.
That's how I remember it.

I don't know about Ontario law,but ...............you might have to have that system operational as pollution-control-equipment.
 
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just get a 72+ pump, it will fit, and not have the 3rd nipple for the carb bowl vent
 
vent to atmosphere, put a small filter or screen on it if you want to keep crap out
 
No. If you find it, leave on there. It serves a secondary function as an anti run-on device.
EDIT
I have seen many of those carbs without a hose on that carb-nipple. In following years,it went to the charcoal canister.I think the CC-storage system like yours,was a 1-year only deal.
 
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You could leave the rubber tube on the bowl vent. Zip tie the free open end to the fuel delivery hose/whatever.
 
In fact, that is where the carburetor bowl vent connects to the crankcase, which was used as the vapour storage location on '70 California and '71 50-state/Canada cars. Don't just go blindly capping and cutting and disabling stuff; fix it right or upgrade it correctly. See here.

There is no throttle kicker.
 
So what I'm reading is I should send it to the breather to enter the crankcase since mine has no canister and goes straight into the crankcase anyways via the nipple on the pump. Correct?
 
Carb bowl vent to extra nipple on fuel pump.
Fuel tank vent to extra nipple on crankcase breather at rear of valve cover.

Or, for improved hot start/hot idle behaviour and to eliminate need for special fuel pump, upgrade to a canister using the parts listed in the article I linked in post № 16 of this thread.
 
Yo Dan, that is bizarre! Any pics of this 71 fuel pump? I cant find one let alone a replacement.
 
Wow, who knew! (Well, Dan did...) seems an expensive alternative to another nipple out the breather as its all the same crankcase? Or did they have to get it low. Interesting. Now Im going to be looking for them on those years.
 
I don't think it'd be too difficult to carefully drill an appropriately-sized and -placed hole in the body of a standard fuel pump and install an appropriate hose nipple using JB Weld or similar epoxy.

But really, the canister upgrade is the better deal.
 
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