identification of SU fuel pumps

[Gene Wescott]

I need to replace my SU fuel pump next May when my car comes out of storage. I have 2 spare pumps,

but one is tagged as a high pressure pump, and the other is unlabeled. I know that a high pressure pump

will flood the carbs, so I don't want to put it on. I have noticed that some pumps have

two points and others just one. What is the difference? How can I tell if a pump is low pressure or high

pressure? There doesn't seem to be an ID number except on the bottom of the base which says SU part

number 4080. This is probably the part number of the base.

Gene Wescott

[C. Knight]

> Gene Wescott wrote: > How can I tell if a pump is low pressure or high > pressure?

If the tag is intact the Low pressure MG pumps will be AUA 25, and Morris Minor low pressure was AUA 66, but has different pipe connections (which can easily be changed). TF was high pressure AUA54. To check a pump without a tag the following may help: All high pressure pumps had a condenser and a bump to accommodate it in the end cover. All LP pumps had flat end covers LP pumps had a 2 BA earth screw, or pre-war, used an extended coil screw for earth, and HP pumps all had a 4 BA earth screws, except the AUA 54 on the TF which has a 2 BA screw but is 1/2 in longer than all the others. The MGA and later HP pumps had 4 BA earth screws and the standard shorter body. The twin contacts were a later improvement by SU and are completely interchangeable. They give double the contact area so are worth fitting. The best fix to reduce contact erosion however is the addition of the condenser, but you will need a non TA/TB/TC original cover with a bump to accommodate it - if that matters!. Hope the above does not confuse Cliff

[David and Joyce Edgar]

Even better than the condenser to reduce point wear in the SU pumb is to add a transistor. It fits under the flat end cap and is completely reversible for you purist types. David Edgar, TC 5108 La Mesa, California

>The twin contacts were a later improvement by SU and are completely >interchangeable. They give double the contact area so are worth fitting. >The best fix to reduce contact erosion however is the addition of the >condenser, but you will need a non TA/TB/TC original cover with a bump >to accommodate it - if that matters!. >Hope the above does not confuse >Cliff

[Gene Wescott]

----- Original Message ----- From: "C. Knight" cliffknight@ic24.net> To: "tabc-forever" mg-tabc@egroups.com> Sent: Wednesday, January 10, 2001 12:00 PM Subject: Re: [mg-tabc] identification of SU fuel pumps > > Gene Wescott wrote: > > How can I tell if a pump is low pressure or high > > pressure? > > If the tag is intact the Low pressure MG pumps will be AUA 25, and > Morris Minor low pressure was AUA 66, but has different pipe connections > (which can easily be changed). TF was high pressure AUA54. > To check a pump without a tag the following may help: > > All high pressure pumps had a condenser and a bump to accommodate it in > the end cover. > > All LP pumps had flat end covers > > LP pumps had a 2 BA earth screw, or pre-war, used an extended coil screw > for earth, and HP pumps all had a 4 BA earth screws, except the AUA 54 > on the TF which has a 2 BA screw but is 1/2 in longer than all the > others. The MGA and later HP pumps had 4 BA earth screws and the > standard shorter body. > > The twin contacts were a later improvement by SU and are completely > interchangeable. They give double the contact area so are worth fitting. > The best fix to reduce contact erosion however is the addition of the > condenser, but you will need a non TA/TB/TC original cover with a bump > to accommodate it - if that matters!. > Hope the above does not confuse > Cliff Dear Cliff Thanks for the information. The tag on the high pressure pump is one of mine handwritten. I think that Mike Goodman identified it once. It is the same length as the other pump, about 2 1/4 inches. It has double contacts with a .047 condenser installed and the later cap with a bump and a vacuum hose fitting. At the base of the body there is a little male hose fitting sticking out of casting flange at 45 degrees. The earth screw is probably a 4 BA, certainly not a 2BA. The casting where the earth screw goes in says 15 on top. So it looks as if it is MGA or later from your description. The other unknown pump looks like a stock TC/TD pump. It uses a 2BA screw for the earth, and has a single contact without a condenser. The body has the partial remnants of a white tag with the letters ..EBU.. I assume that it is a stock low pressure pump which I will have overhauled before I try to depend on it.

[C. Knight]

Gene Wescott wrote:

> > The other unknown pump looks like a stock TC/TD pump. It uses a 2BA screw > for the earth, and has a single contact without a condenser. The body has > the partial > remnants of a white tag with the letters ..EBU.. I assume that it is a > stock low pressure > pump which I will have overhauled before I try to depend on it.

Sounds like an LP pump. I don't recognize the "..EBU.." Check that it is 12 volt, not 6 volt. It should say on the cap. SU pumps are very easy to overhaul at home. No special tools beyond spanners and feeler gauges are needed. New diaphragms and points kits are readily available. If you decide to DIY and do not have access to the overhaul procedures let me know and I will post them. Warning ....original and pre 1980s diaphragms dissolve in modern fuels. The leak sends petrol into the contact breaker area of the case which could ignite. If you contemplate using old SUs take the precaution of fitting new diaphragms from a reputable source. Regards Cliff

[C. Knight]

"Leclerc, Lawrence" wrote:

> > Cliff: I would sure like to see the overhaul directions you refer to. Any > chance of having them posted to the TABC web site? > Thanks > Larry Leclerc

I'll check with the copyright holder. I've just noticed another indicator for L or HP pumps. The outlet valve cage has 4 holes on an HP and only 2 on the L type. Regards Cliff