Nikki Fuel Pump Rebuild

[Captain Obvious]

Rather than taking the bowl covers off, you could just pull off the vent line and stick something down the hole and see if it comes out wet. Like testing a cake.

[dutchzcarguy]

1 hour ago, Patcon said:

the bowls are just drying out

 

34 minutes ago, Mark Maras said:

Removing a float bowl top and having a peek inside would confirm fuel evaporation.

Yeah i did that last month but last week i needed the car (after a stand still of 3 weeks.)  and it fired right up and after about 5 seconds of running on the choke it died.. i suspected the bowls were just emptied. Did not look at the bowls just got me some air from my compressor and bluw them open.. then the car fired right up and i was able to drive it for 10 min. without any problem! 

So i think that there was some fuel left in the carbs.. but the pump could not fill the bowls again.. As i have a few new pumps and no valves (new) i think i just put in a new pump and be done.. sorry for getting a bit.. a lot.. off topic here!

 

[VaCat33]

Rebuild completed. See attached photos. I had to find another original after stripping the threads in one of the screw holes. I used the cap from my original since it was better. Vapor blasted and then reassembled using the JDM parts rebuild kit. I got fresh inlet and outlet from a GMB replacement pump. Found some fresh correct zinc coated screws on eBay. Once things warm up, I can get it installed on car.

FYI…for those of you considering this, The internals in the replacement pumps are pretty much the same as the parts you get in the rebuild kit. You can save yourself just shy of $100 by using the parts from a replacement pump.

Jim

[duffymahoney]

Nice! I rebuilt and sold 10 or so of these over the years.  I used Nos other Nikki pump internals on mine (most cheap off ebay)  The screws were perfect on the NOS.  Then I sent the inlet and outlet off to zinc, then vapor blasted.  

[foosman]

 

On 3/14/2022 at 10:53 AM, VaCat33 said:

FYI…for those of you considering this, The internals in the replacement pumps are pretty much the same as the parts you get in the rebuild kit. You can save yourself just shy of $100 by using the parts from a replacement pump.

Jim

So - it seems from all reports that today's replacement pumps all fail prematurely.  Is that because of poor quality internals, and if so, why would someone want to use them to rebuild their pump?

[VaCat33]

Legitimate question. All I can say is that the internal parts in the replacement pump appeared to be the same as the internals provided in the only rebuild kit that I know of. The rebuild kit cost $125…a replacement GMB pump cost $27. 
Individual call I guess.

[240Znomad]

The problem I found with the modern replacement pumps was that the valves (inlet valve pulling fuel from the tank and the outlet pushing fuel to the fuel rail/carbs) would not seal properly.  Because of that, it couldn't create a strong vacuum to pull the fuel from the tank.  Typically they would work for a few days before failing.  Fortunately, the size and hole pattern on the aftermarket one I was trying matched the size and hole pattern of the OE Nikki pump that failed for me  (the old Nikki pump rubber diaphram became old and brittle and cracked) but the valves were still good and working.  I took the bottom half (containing the rubber diaphram) from the aftermarket pump and the upper half of my OE Nikki and mated them together and it seems to work well. 

Edited March 16, 2022 by 240Znomad

[dutchzcarguy]

Looks like a ballbearing (in this pic) left from the 271070 number... is it for lubrication? or what is that? i see it for the first time.. does anyone know ?

 

[CanTechZ]

1 hour ago, dutchzcarguy said:

Looks like a ballbearing (in this pic) left from the 271070 number... is it for lubrication? or what is that? i see it for the first time.. does anyone know ?

 

That ball retains the pump rocker arm pivot pin. There is one on the opposite side as well. They are pressed into detents in the lower housing to retain the pin, and are not removeable. Mine has a small oil leak from the side you see in the picture.

[duffymahoney]

The chinese pumps valves seem to be one of the fail points.  Maybe I got unlucky, but mine died quickly.  

[VaCat33]

Based upon foosman’s commets about replacement fuel pump quality and the experience related by Duffy in his post, I took another look at the internal parts in the replacement pump.

The rubber gaskets all seemed to be a similar quality. The valves in the replacement pump were, IMHO, of lesser quality. The metal used seemed less durable and they had plastic parts. This might account for the early failure of duffy’s pump and supports what foosman stated.

Luckily, The valves in the rebuild kit I bought were more like the originals.

So look closely at the internal parts, especially the valves, if rebuilding your fuel pump. Hope this helps.

Jim