Fuel Pump and Rebuild Kit

Message Topic Search Topic Options Post Reply Create New Topic Printable Version Translate Topic

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