1976 C-120 fuel pump

[Scrapguy 12]

Having a hard to start issue. Think it’s a weak fuel pump as it runs fine unless I run it out of gas or it sits for a few week. Can this be rebuilt. Possible bad diaphragm from todays ethanol gas?

[gwest_ca-(File Mod) 10,504]

Will gravity empty the tank into a gas can. May be restricted at the fuel outlet?

With the tank above the fuel pump even a weak pump should work.

[ebinmaine 63,218]

2 hours ago, gwest_ca said:

May be restricted

Garry's on to something there. Could be multiple places. 

 

What's the age of the whole set of fuel lines ?

 

Tank filter/strainer been replaced?

 

Carb inlet could be an issue too. 

 

 

[squonk 38,968]

My 76 had a  worn out cam lobe for the fuel pump. Gravity really didn't feed the carb thru the pump. Went electric.

[Scrapguy 12]

Thanks for the replies. Checked fuel lines, all the way from tank to the fuel pump. No blockages, flow was fine. Took apart pump to check diaphragm. While I saw no visible problem with it there are two separate valves, for the lack of a better description, one for inlet and one for outlet. There was a thin washer or gasket floating in there. Closer inspection looks like there should be two of these in there. One on each of these seats. Where the other one disappeared to is anyone’s guess. The lever working the pumping felt like it was working and no wear on the arm. Fuel was in the pump but nothing coming out. Put it back together and it ran for 30 seconds then just quit. Anything else I should be doing? I did order a new diaphragm but I don’t think these washers/gasket pieces are included.

[oliver2-44 8,864]

There should be 2 tiny springs that work with those solid micarda looking washers.  Those springs and washers function as inlet and outlet valves. See the Kohler manual for a good parts diagram. 

[ebinmaine 63,218]

I've got a couple older metal pumps here I could take apart to post pics. 

 

[Scrapguy 12]

Interesting. There were no springs and only 1 washer inside. Certainly explains why just the diaphragm didn’t work. Really wonder where the springs and the one gasket went. Took apart carefully expecting something like that. A picture would be interesting. Since I’m not willing to pay nearly $300 with shipping. What pump do you guys recommend. Seems all are plastic with very mixed reviews. 

[ebinmaine 63,218]

24 minutes ago, Scrapguy said:

Interesting. There were no springs and only 1 washer inside. Certainly explains why just the diaphragm didn’t work. Really wonder where the springs and the one gasket went. Took apart carefully expecting something like that. A picture would be interesting. Since I’m not willing to pay nearly $300 with shipping. What pump do you guys recommend. Seems all are plastic with very mixed reviews. 

 

If there are no springs in your pump it's likely somebody's been in there in the past. 

 

You could go electric.

You could make a block off plate and go vacuum.

You could get a good used pump from somebody like Lincoln at A to Z or put an advertisement in our own classifieds.

 

[ebinmaine 63,218]

7 hours ago, Scrapguy said:

A picture would be interesting

@Scrapguy

 

Here's a few pictures.  

I have 4 Big Block Kohler engine pumps here. 

One plastic. 

3 metal.  

 

 

 

 

I dissected the 2 similar metal ones.  

 

Interestingly, they're different internally.  

 

The one with the discs popped apart and may have been opened up in the past. I do NOT know how the discs are supposed to be in there. 

 

Note the tiny little spring inside the disc.  

 

 

 

 

The other one is set up as so. 

 

One side here is disc over spring. The other, spring over disc.  

That's the check valve system.  

 

 

That one has THREE layer gasket for the plunger.  

 

 

 

[Scrapguy 12]

I’ll check out AT to Z. As far as someone being in there before, no chance. I uncreated this puppy in the fall of 1976 brand new. Think I’d better be draining my oil and fishing in a telescoping magnet. Can’t imagine how these parts are missing but I never had this out before so I’m mystified.

[ebinmaine 63,218]

3 minutes ago, Scrapguy said:

I’ll check out AT to Z. As far as someone being in there before, no chance. I uncreated this puppy in the fall of 1976 brand new. Think I’d better be draining my oil and fishing in a telescoping magnet. Can’t imagine how these parts are missing but I never had this out before so I’m mystified.

Whether you use ethanol fuel or not.. it's possible that the water has been corroding that fuel pump from the inside out. I've had more than one pump here that was pretty much destroyed internally.

[Scrapguy 12]

Mine has the two disc and has the springs inside. From original replies I thought there were springs on top of the discs. So all that’s missing is the one washer or whatever it’s called. Thanks for the photos. Calling A to Z today but not holding my breath that these washer type parts will be available. I see a plastic pump in my future .

[ebinmaine 63,218]

19 minutes ago, Scrapguy said:

Mine has the two disc and has the springs inside. From original replies I thought there were springs on top of the discs. So all that’s missing is the one washer or whatever it’s called. Thanks for the photos. Calling A to Z today but not holding my breath that these washer type parts will be available. I see a plastic pump in my future .

 

There's a company in Massachusetts called 

Then And Now. 

They sell vintage fuel pump parts. 

 

I need those two tiny washers as well. 

 

Might be pricey just for those. 

I've considered trying a little o ring or something.  

[Scrapguy 12]

Called A to Z and ordered new Stens pump and replacement ammeter. Thanks all for your replies.

[23 Reo 221]

I run a fuel pump without a washer on one of the valves. I just seated the valve well with a socket and a mallet.

Works great. I wish I could buy a couple of the valves.

[ebinmaine 63,218]

26 minutes ago, 23 Reo said:

I run a fuel pump without a washer on one of the valves. I just seated the valve well with a socket and a mallet.

Works great. I wish I could buy a couple of the valves.

I wondered if I could do something like that.  

So you just give it the ole smashy smash?? 

[23 Reo 221]

Yes, just tap it in until it is fully seated.

[ebinmaine 63,218]

5 hours ago, 23 Reo said:

Yes, just tap it in until it is fully seated.

You don't happen to remember which way those discs face?

Does one set upside down?

 

[23 Reo 221]

One up one down. On the gas tank side ( in side ) you should be able to blow air into the pump. On the carburetor side ( out side ) you should not be able to blow air into the fuel pump. I wish I could buy a couple of the valves. Sometimes the valves fail not the diaphragm.

[ebinmaine 63,218]

4 minutes ago, 23 Reo said:

One up one down. On the gas tank side ( in side ) you should be able to blow air into the pump. On the carburetor side ( out side ) you should not be able to blow air into the fuel pump. I wish I could buy a couple of the valves. Sometimes the valves fail not the diaphragm.

 

Excellent. Thank you. That's what I thought but wanted to confirm.

 

 

[rjg854 10,753]

2 hours ago, 23 Reo said:

 I wish I could buy a couple of the valves. Sometimes the valves fail not the diaphragm.

Check Then and Now Automotive, 781-335-8860