The Stovebolt Site Forums The Shop Area Engine Shop Fuel Pump Leaking

I just installed a dual action fuel pump on my Chevy 235, so I can use it to run my windshield wiper motor, but it is leaking out of these four holes I circled. This is the first time I have ever used a pump like this, why would it be leaking there? Are there supposed to be plugs in those holes, what are those holes even for? Also, can anyone tell me how to hook the hose for the wiper motor up to this pump, I see there are two threaded holes near the bottom, do I just put a barbed fitting into one of them and plug the other? I should also mention this is an old pump I found, but it seemed like it was in good shape.

The diaphragm probably has a hole in it. Rebuild it or have it done by Then & Now Automotive. https://www.thenandnowautomotive.com/auto-parts-store

Ditto on a bad fuel diaphragm. The lower unit with the bigger diaphragm creates the vacuum boost. Work the pump lever by hand with the pump housing clamped into a vise. The port that creates a suction needs to be plumbed to the wipers. The other port is plumbed to intake manifold vacuum. Those four holes are there to prevent a leaky diaphragm from flooding the crankcase with gasoline in case of a failure of the gas pumping part of the pump, which is what has happened. They're doing exactly what they were put there to do.
Jerry

That all makes a lot a sense, thank you. Does anyone know where I can get a rebuild kit?

Look at the link I posted above. They'll sell you a kit or they'll rebuild it for you. They did mine 10,000 miles ago.

Thank you, I will check them out.

The best bet is to call Then and Now. If you can give them any stamped numbers on your pump they can get you the correct repair kit. There are two styles of linkage connection inside the fuel/vacuum pumps and you may have to disassemble yours to figure out which. Or I'm sure they'd be happy to rebuild your pump for you.

Yes. Calling them is better than trying to use their website.

Friend in h.s. "fixed" his leaking pump on his Nova by whittling stick to plug the hole. All good until the oil pressure light came on. I replaced his pump, drained couple gallons, new oil & filter. Ran until he crashed it. 283 4spd.

The last mechanical pump I had in my Pontiac Tempest filled the crankcase with gas when it failed. On the upside, hey it did clean out the inside of the engine really well! :-D However the Tempest four requires a fuel pump with a smaller diameter than the V8, because of the narrow frame rails, therefore none of the aftermarket Pontiac pumps would fit, even though the armature and mounting (and the sand cast front cover they bolt to) is exactly the same as a V8.

I went to an electric pump and plumbed it into the park light circuit so I'd always remember to turn it off. After the initial time I didn't remember to turn it off, it filled the cylinders with gas, then when I removed the spark plugs and cranked it, there may have been an underhood fire in front of the local diner.. Fortunately they had a fire extinguisher, I could sprint pretty fast as a teenager, and the only damage wound up being to my pride.

I remember a car sitting at our local drive-in restaurant one night back in the late 1960s, a 55 Chevy 2 door hardtop with a beaned-up 327 in it- - - - -with gas dripping out of both tailpipes. The guy was so distracted by his high school cheerleader girlfriend that he forgot to turn off the electric fuel pump that was keeping those two thirsty four barrels supplied!
Jerry

Cheerleader girlfriends can be pretty distracting!