REPLACEMENT PUMP

3/24/09 UPDATE

As of now, V.E. Peterson is only a distributor, they don’t sell to individuals. So I googled GSL393 and the first hit was www.fuel-pumps.net . Phone 800.880.0960. They also have fittings and parts from www.xrp.com . The XRP catalog can be downloaded from their web site. Mostly race hoses and fittings. The out-of-date original note is left complete, below.

8/9/01

Walbro has discontinued the 532 fuel pump. The replacement pump is Walbro part number GSL393. It has an aluminum housing, so it shouldn’t rust, and they say that it is more reliable. It is also physically larger. We have not been able to find a pump the same size as the old 532. This could make mounting a problem, in that the new pump may not fit on the backing plate like the old one did.

The new pump might fit in place of the original pump if 90-degree hose fittings can be located that will mount to the new pump. Although the new pump is made in America, it has 10mm x 1 metric threads on its inlet and outlet. So far, we haven’t found a supplier for a 90-degree hose fitting with metric threads, but they must exist (probably in France or some such place). 5/16 hose is the size of choice, and 3/8 is also fine. 8 mm hose barbs fit 5/16 hose.

We see two straightforward mounting options.

1. Use the straight hose fittings available through V. E. Peterson (the Walbro distributor), part numbers given below. Mount the pump remotely, like below the petcock on the top motor mount or on the frame down tubes. You’ll probably have to fabricate a bracket. Use high-pressure EFI fuel hose for the line between the pump and the throttle body.

2. Find or make 90-degree 10mm x 1 (also called M 10x1 threads) to 5/16 (or 8mm) hose barb fittings and mount the pump to the backing plate using DG26 or DG28 Adel (MS21919) clamps, available from Aircraft Spruce (877.477.7823) or most other aviation parts suppliers. Clamps size DG27 (1 11/16) doesn’t seem to be available, but that what size the pump really is. We haven’t tried this yet. The V. E. Peterson mounting kit (P/N below) uses clamps and a foam blanket. It might work fine if you don’t mind the foam blanket.

Another option is made possible by this new pump. V. E. Peterson has fittings (P/N 128-3039) available that fit standard AN-6 fittings. This makes it easy to use aviation (same as racing stuff) fuel fittings for a very high-class installation. All parts for fabricating such a fuel system are available from Aircraft Spruce, if you can figure out which ones to use. Pro racers know all about this kind of plumbing. The tools aren’t cheap.

Here is a parts list for the simplest installation (remote mount pump) using V. E. Peterson (Walbro distributor) parts.

1 each - Pump P/N GSL393 – about $98.00 each

2 each - 8 mm (5/16) hose barb fitting P/N 128-3024 – about $1.45 each

1 each - hardware kit – P/N 400-929 – about $1.25 each

1 each – mounting kit – P/N 400-920 – about $6.25 each

The hardware kit includes two brass washers to provide a seal for the fittings and two wire terminals. The smaller connector on the stock pump terminal is the negative terminal, the wider connector is the +12 V terminal. The mounting kit includes two clamps and a foam blanket.

If you are using our later fuel pump, it has a 3/8 hose output and a ½ inch input. You might find that using the 9mm hose barb fittings P/N 128-3014 fits better with the 3/8 hose in this case.

This is all theory at this point. We’ve found these parts but haven’t installed them ourselves. A couple of customers have, but they haven’t reported back. Usually no news is good news.

V. E. Peterson will sell direct to consumers and can be reached at 800.537.6212. I have spoken with Jim Brown at that number. They are open from 8-5 Eastern Time. Good luck.