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Arne

Rebuild a 240Z mechanical fuel pump

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For those of us with original fuel pumps on our 240 and 260Zs, those pumps are now at least 35 years old. Obviously, if they haven't yet been replaced, the time of need can't be far away. In most cases, the obvious answer is to simply replace the pump, either with a new mechanical pump or convert to a modern electric pump.

But the original pumps were designed to be rebuildable. For those of us with restored or original survivor cars, rebuilding the original pump is one way to retain some of the car's originality. It's also surprisingly affordable.

Of course, it's not as easy as it used to be. Many of the parts shown below are no longer available from Nissan. But the critical parts are. The diaphragm and the check valves are the parts that wear, and those are still available, as of February 2009.

[B]17053-E3010[/B] - Diaphram - need one - #11 in [B][COLOR="Red"]red[/COLOR][/B] below
[B]17065-21016[/B] - Check valves - need two - #7 in [B][COLOR="Blue"]blue[/COLOR][/B] below
[B]17099-E3012[/B] - Pump to head gaskets - need two - #17 in [B][COLOR="Yellow"]yellow[/COLOR][/B] below

attachment.php?attachmentid=28084&d=1234069330

In addition to those parts (which cost me $15 with my club discount), you'll want to have a couple of fuel resistant o-rings on hand to replace the seals shown as #8 above. Those seals were NLA, but my little o-ring selection had an appropriate replacement in it. But bear this in mind if you need to depend on getting this done in one operation - the old seals appear to have been cork, and will not be reusable. The new ones I used were square-cut, 3/4" O.D., 5/8" I.D., 1/16" thick. They worked perfectly.

As for the process, it's very simple. I didn't take any pictures, but follow along with the diagram above. Remove the pump from the cylinder head. Then separate the upper and lower body halves (6 screws at the diaphragm seal). Once separated, remove the diaphragm from the lower body. You will need to depress the center of the diaphragm down (against the spring pressure) and then out (away from the cylinder head side) to disconnect it from the cam follower in the lower body half. Once disconnected, remove it carefully so as not to damage the shaft seal (under the spring, not shown above). The replacement diaphragm has a pair of flats on the end of the shaft to ease the installation. Insert it with the flats oriented to the front and rear, push down against the spring while holding the cam follower in the extended position, then turn the diaphragm 90 degrees to engage the shaft into the cam follower.

The valves are both in the upper body. Note that one is face up, the other face down. Make note of which is which, because if you get them wrong, the pump will not work. Remove the retaining plate (#9) after removing the two small screws that clamp it down. Using a pair of needle-nose pliers, remove the valves. (I did mine one at a time to make certain not to mix them up.) Most likely part of the cork seal will come with the valve and the rest will remain in the seat. Carefully (don't damage the housing) remove all of the cork remains. Try not to let any fall into the upper cavity. If it gets in there, you'll want to get it back out to keep it from either clogging the pump valve or being pumped into one of the carbs, depending on which side it fell into. If necessary, remove the top cap (5 screws) to get into the cavity, being careful not to damage the rubber gasket under the top cap.

Install the new o-ring seals, then the valves. Re-install the retainer and screws. Test the correct valve placement by gently blowing into the inlet pipe, and then attempt to suck back on the inlet. If you got the valve correct, you should not be able to suck back on it, but blowing through should be easy. The outlet pipe should be the opposite.

To re-combine the two body halves, first make certain that the screw holes in the diaphragm are pretty much lined up with the holes in the lower body. Operate the cam follower arm to pull the diaphragm down flush, then set the upper body in place and secure it with one of the screws. (A third hand can be handy here. Another option would be to re-install the lower body back on the cylinder head and turning the engine by hand until the diaphragm is pulled down.) Continue with the other 5 screws, don't over-tighten them. Once assembled, operate the cam follower arm a few times, you should be able to hear it pumping air.

Clean both sides of the pump spacer (#16) before installing the new gaskets (#17). Bolt it back to the cylinder head, attach the fuel lines and you are done.

This will work well as long as the diaphragm and valves are still available. Another option for people bent on originality might be to purchase a brand new Kyosan Denki pump and transfer all its new parts into the original body. A bit more expensive, but perhaps worth it for some people.

post-8596-1415080608939_thumb.png


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Very nice writeup. Thanks for including the part numbers too.

I only have one thing to add. Don't install the upper half of the pump backward, or else the pump will move fuel in the wrong direction and leave you scratching your head as to why your float bowls ran dry. I wonder how I know that?

Edited by blue 72

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Very interesting, Arne. I think I'll rebuild one of my spares and put it on to replace the one that's on now - that's seeping a bit of oil (around the pivot pin, I think) and it tends to throw a drop or two after each drive.

Also, the diagram that you reference isn't showing up on my screen. Any thoughts on how to see it?

Thanks for the time & effort that you put into sharing this.

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Very cool! Thanks! I can't view the picture either, but I can view the exploded diagram. Great article!

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I kept my original just in case I could rebuild it. Only thing I need is a parts source - my local Nissan dealer isn't much help.

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I kept my original just in case I could rebuild it. Only thing I need is a parts source - my local Nissan dealer isn't much help.
Even with the part numbers? If you give them part numbers, I should think they'd order for you.

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This is exactly one of those "get one done now" deals. Wait until you need to do one only to find out these parts are NLA, will not be good.

Arne, Leroy say you done good....... You can in fact lead 'em to water......

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Even with the part numbers? If you give them part numbers, I should think they'd order for you.

I will try, if they are available, then there should be no reason they can't get the parts.

Do appreciate the post - this has been bugging me since I switched mine out.

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If that doesn't work, contact Russell Moore at nissanparts.cc. If they're available, he will get them for you. 1-866-754-5500.

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If that doesn't work, contact Russell Moore at nissanparts.cc. If they're available, he will get them for you. 1-866-754-5500.

Stephen,

Thanks - always good to have a backup channel!

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A quick note - after hearing from another member here that his dealer wasn't able to get the check valves, I have confirmed that those valves are now shown as 'back-order' with no ETA. Not known whether any more will be offered in the future.

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Awesome, thanks for the info. Ordering my parts right now.

I completely dismantled my fuel pump a few years back trying to troubleshoot something else, and my diaphragm was showing some signs of wear (It'll probably show some light surface cracking by the time I pull it out). Back then I just assumed the parts were nowhere to be found, because one of my manuals (Haynes maybe? FSM?) listed this as a "non-serviceable part."

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hey Kerrigan, i'm in need to rebuild mine. Is it possible to pm me where you got them or post here? Thanks in advance.

I was able to obtain a rebuild kit out of Canada last week, so they are still around.

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Arne, EXCELLENT WRITE UP!  Thanks.  I hope you are OK, I took your excellent written instructions and added photos.

Datsun 240z mechanical fuel pump rebuild.

I gave you credit several places.  For me, photos really help, especially down in the deep-dark spaces where you can't see!

Regards.

  • Like 1

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You should add to the rebuild writeup that the info applies to the Nikki pump ONLY because of differences in the diaphragm design. Replacement diaphragms fit the Nikki and don't interchange with the Kyosandenki pump.

http://www.classiczcars.com/topic/50224-fuel-pump-parts-interchange/?p=457702

Edited by NVZEE

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On 10/04/2014 at 5:01 PM, Kerrigan said:

I was able to obtain a rebuild kit out of Canada last week, so they are still around.

Hi Mr Kerrigan. My pump is the "Ampco G 22 " pump and I need the correct diaphram so I wonder if you could give me the site in Canada where you got your kit from.Thanks for you time.   Kind regards.TonytomB

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Hi siteunseen.  You may have seen my post to Mr Kerrigan if not I need  a diaphram with rod to fit my ampco petrol pump for a 260z 1974.  Could you supply me with any leads.  Kind regards. Tonytonb

On 05/12/2016 at 3:45 PM, TonyTomB said:

Hi Mr Kerrigan. My pump is the "Ampco G 22 " pump and I need the correct diaphram so I wonder if you could give me the site in Canada where you got your kit from.Thanks for you time.   Kind regards.TonytomB

 

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