mechanical fuel pump reinstall 72Z

[Patcon]

It can be difficult to get the pump to prime especially by hand.

the internal valves will sometimes get stuck from dried gasoline in them

[jitenshakun]

4 hours ago, swflaz said:

 

 

Edited November 7, 2021 by jitenshakun
Accidental repost

[jitenshakun]

3 hours ago, swflaz said:

yes, i have. first pulled off the two fuel hoses that come off the fuel rail into the carbs and was able to blow thru both. So, no clogged needle valves. 

next i removed the fuel pump (didn't do it on the car for several reasons) to do a manual operation check. with a fuel hose on the entry side in a small container of gas  i manually pumped a bunch of times and it was not delivering fuel. so that's the problem. Before i replace the pump i'm taking it apart to see what the problem is. Might have to replace it but it was rebuilt a few months ago. Maybe the diaphragm got compromised some how. More later.

They seem to do odd things when they go back together. Easy part can feel ok, but then they don't work. I don't have a solution, just saying the mech pumps are a pain. 

[swflaz]

Thanks i'll keep that in mind when i check it out tomorrow and let you know. Do you recommend using carb cleaner?

 

[jitenshakun]

I don't think it's a gunk or cleanliness problem. My guess is the diaphragm itself just doesn't play nicely with the spring at some point. I tried rebuilds, new aftermarket pumps, and combinations of tops, bottoms, and internals between all of it. 

I gave up without a mech solution. 

[swflaz]

As far as mechanical pumps go, i may wind up giving up on them as well. i'll know in another day or two. Thanks

[swflaz]

OK, got at the root of the problem. It turns out that the 2 valves were indeed installed incorrectly. A little embarrassing since I was so convinced the rebuild was right. Anyway, after a couple of disassembly and reassembly attempts it is pushing fuel thru just fine just by hand pumping. It was a bit of a bear to get back on but is now reinstalled. didn't try to start it yet since it was late and i was not in the mood to start trouble shooting if necessary. Plan to try to start first thing in the A.M. Fingers crossed. Thanks to the contributors. i'll report back one more time after it starts.