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Fuel Pump and Rebuild Kit

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sean View Drop Down
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    Posted: 18 Jan. 2010 at 12:44pm

GROUP 12-09 -- FUEL PUMP

Part No. 640160 -- Pump, Fuel, Assembly

(photos enlarge, just click 'em)

AC Series AF, Model 572, AC Part No. 1538886

          


Part No. 640586 -- KIT, Fuel Pump


Willys rebuild kit is fairly comprehensive (a modern rebuild kit may or may not include all the same parts), see the contents list here:

Fuel Pump Rebuild Kit

The parts you have to re-use.  The spring centering washer (red arrow) may or may not be needed, depends on the diaphragm in the kit (more details further down):



Re-assembly: this is not an actual rebuild, just a mock-up to show the steps.  The bowl, gasket, bail & strainer not included.

The actuating rocker is 2-piece, held together with the pin.  The inner hooked lever is free to articulate independently of the cam lever.  The hook fits the slot in diaphragm shaft.

               

The lever pair is held in the housing by the pivot pin.  The factory pin is a straight dowel w/beveled ends.  The casting is peened around the bevel to hold the pin in place (the rebuild kit pin is different: see further down for details).  The spring holds the rocker arm in contact with the cam lobe at all times. 

          

Check valves are installed (w/paper gaskets) in opposite directions (red arrow is the "inlet"), and held fastened with the "H" clip:

               

The upper and lower halves are ready to be joined.  If the steel cup on the diaphragm is larger then the spring, then you'll need the centering washer.  Check the slotted end of the shaft (red arrow) for sharp edges, nick and/or burrs that might damage the rubber oil seal.  Lubricate the seal & shaft.

               

Insert the oil seal & spring seat washer in the lower housing.  Line up the slot so it will engage the hook.  Tilt the casting so the hooked lever free drops to its "upward" position.  Push the shaft through the oil seal (not shown for clarity) at an angle and maneuver it until it "slots" over the hook.  When you let go, the spring will push the diaphragm out a ways, and at an angle.

               

The 2 halves can now be screwed together w/the diaphragm - READ THE SPECIAL INSTRUCTION INCLUDED IN THE PHOTO OF THE "KIT" ABOVE!

Parts differences.

The original pivot pin vs. the replacement pin.  The original is scored & worn.  The replacement has a shoulder on one end, with a "hollow rivet" type extension on the other end, which gets peened down over the retaining washer:

          

Different diaphragms.  I've found 2 different size "spring seat" cups on diaphragms.  The larger one needs the centering washer to prevent the spring from moving off-center, which would unevenly load the diaphragm.  The smaller one fits the spring exactly w/out the washer:

          

Now there's a conundrum:  the NOS rebuild kit has a large cup diaphragm, yet the centering washer is not listed in the parts list, or shown in any factory illustration, or included in the rebuild kit!

In fact, the opposite.  The factory illustration from the '45 Maintenance manual shows the small cup diaphragm!


Go figure.

Sean
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Howard Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan. 2010 at 4:35pm
Very Cool Sean,
According to the TM9-1828A Manual, failure to hold the diaphragm, as instructed, while securing the cover screws will cause the pump to deliver too much pressure. There has been some debate about this instruction. Undoubtedly what they are referring to in your instructions included with the kit. Some of these pumps have the oil seal and spring as shown in the drawing, they were on the diaphragm shaft.
Here is a drawing from the same manual. Hope it is of some value as well. Not a good reproduction of the drawing. Sean, any help?
Edit...I removed the drawing I posted...Larry's got it below!
 Thanks Larry!
 
 


Edited by Howard - 18 Jan. 2010 at 8:16pm
Howard F Jewett

1946 CJ2A #23353

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43 Bantam Trailer T3 #14844

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Post Options Post Options   Thanks (0) Thanks(0)   Quote rocketeer Quote  Post ReplyReply Direct Link To This Post Posted: 18 Jan. 2010 at 5:54pm
Sean here's the diagram and instructions from TM9-1828A. If not appropriate to this thread let me know and I'll remove the post. Take note that when talking about the oil seals it says "If used".





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Post Options Post Options   Thanks (0) Thanks(0)   Quote sean Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jan. 2010 at 10:23am
Thanks guys.  The descriptions in the TM are more detailed, but the illustration depicts oil seal parts not used in CJ-2A, could be confusing.  That is a "typical" AF pump, not specific for MB or CJ-2A.

The 2A Service Manuals and Parts Lists have the right illustrations.  The first one I posted above (same as TM-10-1513), and this one (same as SNL G-503, MB Parts List)::


As for the TM diaphragm instructions, at best confusing, at worst wrong (it might be appropriate for some other vehicle pump, but not CJ-2A).

The diaphragm must be in fully flexed position before tightening the cover screws.  That occurs when the rocker arm is released, allowing the spring to force the diaphragm upward, limited only by the 6 cover screws.

If it's clamped w/out flex, it can't create enough pressure or flow.

The written instructions in the kit:

"... move the rocker arm until diaphragm is level with the flange surface.  Place cover in position with screws drawn down ONLY FINGER TIGHT.  Release the rocker arm, which will flex the diaphragm to the correct amount, then tighten cover screws ..."

Sean
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Howard Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jan. 2010 at 11:01am

This diaphragm installation has generated some debate in the past among collectors. Sounds like some other erorrs in the TMs...or at least some misunderstandings in interpretations. The kit instructions make sense but a pressure test would verify the actual output from the pump.

FWIW, There is also some referance to testing the output pressure, valves and diaphragm function after assembly.
The TM says,
"...attaching pressure gage to pump outlet. Operate priming lever or rocker arm until gage shows 3 psi. Discontinue building up pressure and observe time required for gage pointer to drop from 3 to 2 psi. A time lapse of 5 seconds or more indicates a satisfactory pump."
 
Would this be a proper test? It sounds odd to me. At best it would be testing the check valves. No referance to volume. I have never performed this test to know what my fuel pumps have put out after rebuild. But my pumps have worked just fine...Smile
 


Edited by Howard - 19 Jan. 2010 at 11:04am
Howard F Jewett

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Post Options Post Options   Thanks (0) Thanks(0)   Quote sean Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jan. 2010 at 12:03pm
Howard:
Quote ... Sounds like some other erorrs in the TMs...or at least some misunderstandings in interpretations...
I think a little bit of both.  Many of the TM procedure descriptions are poorly worded, and ambiguous at best.  And it carried over into CJ-2A manuals too.

Quote Would this be a proper test?
Sounds reasonable for a minimum tolerance test.

ie. if it can't reach 3 PSI, there's a problem, and if it leaks down too quickly, there's a different problem.

Keep pumping and it should max out at 3.5 - 4.5 PSI ("new" pump spec.)

Quote I have never performed this test to know what my fuel pumps have put out after rebuild.
A quick-n-dirty pre-assembly test would give you a rough idea.

Measure diaphragm spring force on a scale when compressed to @ .8" high (installed height).  Should be around 13 lbs or slightly more.  The diaphragm is @ 2.25" diameter (@ 3.8 sq-inches), 13 lbs gives you @ 3.4 PSI.

Sean
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Craddman Quote  Post ReplyReply Direct Link To This Post Posted: 28 Aug. 2017 at 1:21pm
Reviving an old thread. Newbie here. I own a 1947 CJ2A. It has been in our family since 1964 and we have had it in use that entire time; first as a personal vehicle and for the last 45 years as a utility vehicle on vacation property we own. With a little TLC it has worked well until it wouldn't start this spring after sitting over the winter. After some trouble shooting it would appear that I have a bad fuel pump. I have removed and cleaned the fuel pump but there are no markings other than a label on the glass bowl that says "Made in Canada" (I would assume not original). I assume all that is required is the diaphragm - (I will also need the mounting gasket) but I have yet to disassemble. Any ideas on where to look for a replacement diaphragm - rather than trying to find an entire new pump? The ethanol in the gas added in recent times may be wreaking havoc on older materials. Any assistance is appreciated.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote athawk11 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Aug. 2017 at 1:28pm
If you had the original style pump shown above, it may be worth rebuilding.  If you have a glass top, it is a replacement.  For the price, it may make more sense to buy a new pump.  They are around $40.00 and will already have diaphragms that will hold up to the ethanol fuel mixtures.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Craddman Quote  Post ReplyReply Direct Link To This Post Posted: 28 Aug. 2017 at 1:44pm
WOW - amazingly fast response especially given the age of this thread. Thanks Wink. It is, in fact, a glass top and now that I think about it, I'd probably replace the gasket that the glass top seats against since it seems a little brittle so given the cost of the new pump (and considering I'm not trying to keep everything original) it looks like buying new is the best route. I don't want you to do all of the work for me but since I'm here... Any ideas of where to get the new one and or a model/part # or other spec. that I'll need to get the proper pump?

Thanks again for the assistance - much appreciated. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Stev Quote  Post ReplyReply Direct Link To This Post Posted: 28 Aug. 2017 at 1:55pm
A little more life into this thread - What do you do if you have a historical pump and it works fine to pump gas but the rocker arm pin leaks oil down the side of the engine.  What is the fix?  Machine a bigger pin? Is the pin suppose to move once installed - this one shifts.
Stev
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Post Options Post Options   Thanks (0) Thanks(0)   Quote athawk11 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Aug. 2017 at 3:37pm
Craddman,  I purchased and installed this pump.  It works as it should.


These are fairly common.  You might even have luck at the NAPA store.

Stev,
I wonder if you have enough pin to peen it a bit?
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