Rebuilding the Pierburg Fuel Pump

Part of restoring the 1200cc to 1600cc engine by the (VW) book
By Dean Kirsten | March 2, 2012

Photos by Dean Kirsten

If you are doing a body-off restoration of a 1966-1969 Bug, and want the engine to be 100% correct, then don't forget the fuel pump! The original pump for these models came from A.Pierburg KG (Germany), and proudly displays the VW logo on both sides. That last bit of detail is most important for the purist restoring these engines. Sure, there are dozens of different pumps out there that will work and look right, but without that VW logo, they are ... no cigar.
This is what you are looking for at the swap meets — the A. Pierburg named with the VW logo. Some aftermarket pump had the round VW logo machined off, so finding an original pump can be a bit tricky. Our $5 find.
In locating such a pump to rebuild, we did what most of you do, search the VW swap meets for a good rebuildable core, one that had a good casting and was free of porosity. We found this one in Dade City, Florida for $5.00. From there, we purchased a rebuild kit from Wolfsburg West, (PN 111-198-555) for under $30. So total investment was $35. For the 1200-1600 engines, the most popular pump has a square top with four small screws attached and slip-style fuel lines, while the earlier 40hp version, has a round metal cap with one fastener located right in the center, and screw-in fuel lines. There is also one for the 36hp engines, and kits are available for each of these pumps from Wolfsburg West.
Companies like Wolfsburg West sells fuel pump rebuilding kits for under $30, but they do not come with new delivery pump, suction valve or filter insert.
In order to rebuild this pump, you need access to a gallon can of carburetor cleaner (dip), which will (or is supposed to), remove the grease and grime, leaving only the bare base material. But before making the plunge, you need to remove the internal valve and spring assembly, which is pressed into the top housing. You have to tap this aluminum ring from above, using a small punch, which releases the ring, small Bakelite round disc/valve, and spring (note, these parts are not included in the current rebuild kit, so you will have to reuse them). After disassembly, and taking notes how this pump was put together, we dipped the parts overnight, then rinsed them with water.
Removing the six main screws opens the pump at the diaphragm.
From there, we decided to go one step further and media blast the main castings. Here, you really need to use your head because you can easily blast-away and ruin your pump with too much pressure or too aggressive blasting media. We used Paul Schley's blast cabinet, but first turned down the pressure and made sure the material was a mild blend of media. We took care to only "dust" the castings and not get too close. The result of our careful blasting was a nice clean appearing pump body, ready for cleaning and assembly.
Remove the fuel pump cover and lift of the cut-off diaphragm and spring.
Before we started assembly, we also cleaned all the screws and hardware with a fine wire wheel, then clear-coated them to prevent rust from returning (cadmium plating would be the preferred method if you have the budget and time). We also flat-sanded all the mating surfaces to insure no leaks, using a piece of 150-grit paper placed on a flat plate. Actual assembly took about a half-hour, and the trickiest part was hooking up the operating lever to the main diaphragm shaft. We pushed the diaphragm down using our right thumb, and at the same time, using our left hand, inserted the lever through the inspection opening, then slipped the two together. From there, you need to align the lever with the two main housing holes (one on each side), so you can insert the pivot pin, followed by the two circlips, and the spring.
To remove the delivery valve assembly, you need to tap it out,using a punch from above.
The rest of the assembly is really straightforward, including tapping back the previously removed Bakelite valve/spring and aluminum ring back in. Just use care when you insert screws through the diaphragm holes so that you do not twist or tear the material. Lightly snug all of the screws together, to make sure the housing pulls down evenly. Finally, don't forget to re-install the cone-shaped filter (not included in the kit), and add grease to the bottom lever assembly.
Here's what the delivery valve assembly looks like. If you plan to boilout the pump, then remove it. Otherwise, do not, since new parts are no longer available, and you risk damaging it.
To remove the lever pivot shaft, you need to remove both clips (one from each end), and then tap out the shaft with a punch as shown. Looking through the inspection panel (with cover removed), you can see the shaft, lever and spring.
Once the shaft has been removed completely, the lever and spring can be removed, using a pair of needle-nose pliers.
Now the main diaphragm can be pulled out. Usually by now, these diaphragms are really dried out and crispy to the touch. They are supposed to be soft and pliable, and free of cracks. Now that the main pump body has been assembled, it is time to clean it, which usually requires a dip in a cleaning solution made for cleaning carburetors and such.
We threw all of the fuel pump parts into the carburetor cleaner can, and left them overnight.
If you have access to a bead-blast cabinet, then, you can clean the castings with low pressure and fine media.
Flat-sand all mating surfaces.
To engage the pump lever to the main diaphragm shaft, use your thumb to depress the diaphragm, and then insert with your left hand.
Once the lever is engaged, you can install the shaft, two circlips and then the spring, using a pair of needle-nose pliers.
To re-install the delivery valve assembly, you need to tap it back in place, using a socket for example, and a small hammer. Don't forget the spring and flapper-valve (Bakelite).
Replace the suction valve (thin piece of metal) and retainer, then secure them with a small screw.
To replace the top section, you need to align all the six screws holes, inserting them through the diaphragm without tearing or kinking it.
Next comes the delivery valve (diaphragm), spring and gasket as shown. Fit the top cover and tighten the four small screws evenly.
Reuse the existing cone-shaped filter, fit a new gasket on the brass fitting plug, and tighten.
SOURCE Wolfsburg West 2850 Palisades Drive Corona, CA 92880 (951) 549-0525

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