Late Fuel Pump Design Question

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v8_ranch
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Late Fuel Pump Design Question

Post by v8_ranch »

Well, I finally snuck a few minutes tonight to remove the fuel pump from my newly acquired 68 2000. Other than a tight fit with a wrench and realizing I clearly have justification now to buy a good set of ratchet end wrenches, the pump came off really easy. I was relieved after hearing and reading about what a pain it might be. I then took the diaphragm cover off and after being that stem was not going to release and pull out no matter how I twisted and pulled, I questioned if I had the pump that less than desirable to rebuild? So, took a break and read info on the Rallye site and convince now I have the later pump design.

That said, I am wondering about something, and maybe someone else has tried it before? My background is managing power plants. We had small small vacuum pumps in the plant that had to have the diaphragms replaced after so many hours of use. The design was such that the diaphragm rubber piece had a hole for a screw to go through and attach the rubber piece to a metal backing disc. I see on my pump, that it has more or less a rivet connection instead of a screw as I am describing. It is possible to drill and tap what is behind that in order to be able to rebuild this fuel pump as I am describing from my vacuum pump example? It may not be worth the hassle, as I am not even sure what a replacement pump will cost me, or if there is yet some other way to still rebuild this pump, but thought I would throw it out there.

Thanks
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Shane

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Re: Late Fuel Pump Design Question

Post by v8_ranch »

Ok, found a write up on the later style pump where it said to secure it in a vise and the. Rotate disc/diaphragm 90 degrees clockwise and tug and jiggle... crap, it worked! So now, my plunger does have the “T” end... is the rebuild kit I need just the normal kit. looks like I could probably get away with just a new plunger/diaphragm piece if nothing else. And will be replacing the screws on the body. Any need to remove the other cover on the part with the valve?
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Re: Late Fuel Pump Design Question

Post by v8_ranch »

who ia typically fastest source for these rebuild kits?
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Re: Late Fuel Pump Design Question

Post by DAC21 »

v8_ranch wrote: Wed Oct 21, 2020 2:06 am who ia typically fastest source for these rebuild kits?

Nissan Dealer, p/n 17053-32201, should be $13 or less. The upper gasket and valves are still available as well if you are going to open up the upper chamber. Highly likely it will need to be ordered by your Dealer but no upcharge for shipping and you should have it in hand within a couple days. Don't forget new gaskets (2) and there should be a thin spacer as well that could still be stuck to the block. That must be reused or replaced or you may well destroy the FP and some claim screw up your crank. PM me if you need additional part numbers for these other items.
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Re: Late Fuel Pump Design Question

Post by JT68 »

Most of the fuel pumps cannot be disassembled this way. Your pump had the early style lever, those are the only pumps that will come apart with the push/turn 90 method. If you try to remove the pivot pin, you will crack the casting.
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spl310
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Re: Late Fuel Pump Design Question

Post by spl310 »

The early style lever is a riveted together lever. That is one of the later designs that is a stamped unit.
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Re: Late Fuel Pump Design Question

Post by JT68 »

Right Sid, they changed the lever design later in production. Most replacements pumps made through the 70's,80's',90's cannot be disassembled by push and turn.

Most original Nissan pumps can be.

KyosanDenki added a tang to the lever on the pumps later in production that prevents disassembly.

All the riveted style arms can be disassembled and re-assembled that way as described, only some of the later style (shown), will come apart that way. Since we rebuild them, I've probably disassembled 3 dozen pumps..
Last edited by JT68 on Wed Oct 21, 2020 7:08 pm, edited 1 time in total.
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Re: Late Fuel Pump Design Question

Post by 70MTRoadster »

I rebuilt the pump off my 70 1600 with a new T diaphragm from Dean at datsunparts.com. Easy peasy and works just fine.
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Re: Late Fuel Pump Design Question

Post by DAC21 »

In theory these pumps don't even have to be removed from the engine block to pop the top off to rebuild? Assuming you have confidence in the Pump gasket / spacer to engine block condition?
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Re: Late Fuel Pump Design Question

Post by v8_ranch »

Well, crap... here is my update. So, it looks like I actually do have one that cannot be rebuilt (easily). I started to put it back together today after getting all of my parts and no matter what I did, I could not get the plunger to twist and lock as easy as I had been shown that it should... So, I looked and scratched my had and looked some more, and then after talking to Sid (spl310) I measured the dimensions of the T and compared it to the one I pulled out. I thought BINGO! The new one was slightly bigger. I tried to file it down to match, and still no joy. It just seemed like there was no way I could get the T underneath arm with the extra piece sticking out into the area (See picture). Then I found a closeup picture of one that was being rebuilt in a youtube video, and bingo, it did not have the extra piece mine has sticking in the way, AND the arm pieces have more of an opening farther back (if that makes sense) that would allow more room for the T to slip in and then twist. Then I reread this thread, and saw JT68's reply and that pretty much helped me understand I was seeing what was wrong with my rebuild the right way.... SOO, here I am, and I am wondering something. JT68 said that extra metal was added in order to prevent rebuilds. Can I put this thing on a drill press and clear out a little more material on that arm so that my pump is more like the Nissan pump? Obviously, it will be cleaned out thoroughly afterward, before reassembly. I don't see any reason that part needs to be like that other than what JT68 mentioned. Maybe I am missing something critical though?

First one is mine, second is one that was easily rebuilt in a video...
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Re: Late Fuel Pump Design Question

Post by JT68 »

The metal is there to prevent the arm from disengaging during operation, not to prevent disassembly. As you can see the levers are also different.

If you try to drill/press out the case hardened shaft, you will break and ruin the pump.

If you modify the housing, you will ruin it as well.

You can buy a wire edm machine to correctly disassemble the pump the way we do, send us your pump for rebuild, or just buy a rebuilt pump. Or you can always find an earlier pump and rebuild that yourself.
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v8_ranch
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Re: Late Fuel Pump Design Question

Post by v8_ranch »

JT68 wrote: Fri Oct 30, 2020 8:58 pm The metal is there to prevent the arm from disengaging during operation, not to prevent disassembly. As you can see the levers are also different.

If you try to drill/press out the case hardened shaft, you will break and ruin the pump.

If you modify the housing, you will ruin it as well.

You can buy a wire edm machine to correctly disassemble the pump the way we do, send us your pump for rebuild, or just buy a rebuilt pump. Or you can always find an earlier pump and rebuild that yourself.
No, i'm done playing and thinking about this one, haha. And as much as I would love a wire EDM to play around with in the garage, haha, don't think my wife will see anything I come up with as a worthwhile excuse. I found the leftovers of an older style pump tonight and will use them to rebuild the rest of this one I guess and call tonight's adventure a productive waste of my time, haha.
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Re: Late Fuel Pump Design Question

Post by v8_ranch »

I guess fought it simply because it did actually come apart, and the stuff I was reading before that point made it sound as though it would only come part if it was the more easily rebuildable style. Once I saw what was going on with the T and the arm in the pump, I think I just was in that mode of "come on, this can work somehow"...
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Re: Late Fuel Pump Design Question

Post by DAC21 »

[bbvideo][/bbvideo]
v8_ranch wrote: Fri Oct 30, 2020 10:38 pm I guess fought it simply because it did actually come apart, and the stuff I was reading before that point made it sound as though it would only come part if it was the more easily rebuildable style. Once I saw what was going on with the T and the arm in the pump, I think I just was in that mode of "come on, this can work somehow"...
I'm wondering if the pump is non OEM? Like you everything I have read about OEM pumps is that if it has the T flange and comes apart with relative ease it can be rebuilt. The two T flanges between the old Diaphragm and the new one are identical? Odd that if it came apart it wouldn't reassemble other than it came apart because the internals broke to allow the diaphragm to be released.
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Re: Late Fuel Pump Design Question

Post by JT68 »

Kyosan Denki made thousands of these pumps for decades sold through Nissan and aftermarket.

Rallye described the issue 30 or 40 years ago and they were correct. Its well explained in the posts above.

Many of the pumps simply weren't designed to be serviced- they cost 10$ back in the day, so
I'm quite sure they were considered disposable items.

The auto industry has been slowly migrating to that philosophy for 50 years at least.
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