Large Fuel Pump Long Term Storage and Maintenance

[George Des]

In sorting through and re-testing a number of large fuel pumps I refurbished and stored several years, I'm finding that several of them are suffering from the ill effects of long term storage without having been thoroughly purged of fuel from the time they were tested.  In some cases, the vane is sticking and in others, the bellows seal has stuck to the mating surface. This doesn't present a major problem unless repeated attemps are made to get it going by applying power. Two things will most likely happen if you do (1) The windings and/or the armature will burn out or (2) the tab washer will break free allowing the armature to spin while the bellows stays stationary resulting in the pump pumping fuel but with no sealing action--it will eventaully leak from the leak-off pipe. The best thing to do if the pump doesn't turn over immediately on applying power is to remove the bottom plate and determine where the pump is sticking. If it is the vane, it is a simple matter to remove it and the woodruff key to clean up the vane and the inner pump surface. If is the bellow seal, you can try applying a little oil around the bellows and gently twisting the bellows by grabbing it with a set of needle nose pliers and turning it--do not try to turn the armature because if the seal is stuck really hard you will break the tab. In this case best to remove the split ring holding the bellows and pull it straight up and off to clean the seal surfaces. If you break a tab washer, let me know, I have plenty. Those who have extra pumps they are storing may want to be mindful of this when the time comes to install that extra old style pump you have in storage. It may be a good idea to remove the bottom plate before storage applying some light oil around the vane and seal to avoid this problem entirely. This isn't quite a problem with the smaller pump because the sealing system is much different, but the vane itself can also stick on this pump. This may be appropriate for the tech manual should someone know how to enter it.

Hope this helps.

George

[George Des]

Quite some time ago, I wrote up a set of instructions on how to size the oring armature seal for the long style fuel pump by "sanding" it to size. I have found that you can get a good seal here w/o the "sanding' operation if you use a 1.2mmm x 3.2 mmm oring and 'stretch" it over the armature into the appropriate groove. It will allow the bottom of the bellows seal to slip past while properly lodging against the top upper inner portion of the bellows forming the proper seal. The tech manual instruction suggests that a 1.0mm x 5mm will also work but I have never had much luck using that size oring. The repair kits I have sent out have included at least two or three 1.2x3.2mm orings so if you purchased one of these kits you should not need to go through the sizing procedure for the shaft seal but you will need to be careful in stretching it over the shaft to avoid splitting it..