MGB Mechanics
SU electric fuel pump replacement

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In november 2007, while getting into the MGB to attend to the Gazoline's monthly meeting in Bailly, France, my MGB GT's engine stoped after one or two minutes idling. Once restarted, the car could not accelerate properly. I first checked ignition and HT wires but finally found the fuel pump did not operate.

A dead fuel pump is not a big issue but it can immobilize your car while driving far away from home. Fortunately, it happened to me while the car was parked in its garage.

I lifted the MG, un-plugged the hose and checked for flow with ignition switched on : only a few drops of gas came out, the pump was silent.

As petrol came after giving a few knocks on the pump, it became obvious the points need replacement.

New point sets are available from parts retailers (part number : AUB6106A ), but I decided to change the wole pump.






1st step : find a new MGB -positive earth- fuel pump.

MGB spare parts are available almost anywhere, and there are many alternative fuel pumps. Some are electronics (and polarity concious). But I wanted an original SU replacement to avoid any change in pump's fittings and hoses.

My MGB GT is a positive earthed mark 1. Original  part number is  AZX1318, but positive earthed fuel pumps are non longer availables :

Fortunately SU fuel pumps are now dual polarity. I bought one from the MGB Hive for only 52.50 GBP.
Su fuel pump packing
The item was delivered quickly.

SU AZX 1307 Fuel Pump
Take care when removing the yellow plugs. The pump contains a bit of anti-seizure oil.


SU AZX 1307 Fuel Pump
Only few instructions, written before september 2004.

SU AZX 1307 Fuel Pump

So an add on indicates the new fuel pump part numbers since 2004. When these became "dual polarity"
.


MGB SU AZX 1307 Fuel Pump

Fuel pump seal colour code for identification :
Positive earth = red seal.
Negative earth = black seal.

SU AZX 1307 Fuel Pump

So what a blue seal means ? As it was not written in the instructions, I assumed this is for dual p
olarity..

SU AZX 1307 Fuel Pump

As British Leyland / Rover part number is stamped on a plate located to the pump's body. AZX1307 is the replacement part number for original positive earth fuel pump : AZX1318


2nd step : Su fuel pump replacement

I did no know anything about dual polarity fuel fuel pumps and I was scared by the eventuality of a short circuit  on a fuel line device, so i made every measure to minimize any risk :

- electrical main feed disconnected
- prevent from any fuel leak
- prevent any fire

MGB sur chandelles
Once lifted, the MG leans on its left side. Fuel in the tank naturally goes on the side opposite to the fuel pump.


Rocker switch console prototype
Therefore, expect to collect around 1Litre of petrol.



mgb-switches-console-prototype
Security first. The battery is disconnected, the MG is on a stand, sand would stop an eventual petrol flood, while fire extinguisher is immediatly reachable.


        
mgb-console-steel-panel
The Su pump's hot connection is this this beige wire. The green wire is connected to the earth.



Rocker switch console prototype
The old pump removal : petrol leaks from the hoses. The mounting bracket is attached to the body with two 7/16 nuts


.
Pompe à essence SU
The new pump's outlet is clearly marked. Beside is the earth connection.






mgb-switches-console-prototype
The mounting bracket is fitted to the new fuel pump prior to connect hoses.



mgb-switches-console-prototype
Now the new MGB fuel pump is fitted to the inner body. The bracket's lower nut (7/16) is visible on this picture.


Rocker switch console prototype
The collected petrol can be used to clean the old fuel pump.





    mgb-dashboard-additional-switch-console   

With ignition on, the new fuel pump starts its usual rattling. Check your fuel line for any leak while the car is still jacked, and once back on its four wheels with engine started.

While engine is started, expect some fuel to come out of the carburettors overflow pipes. This is surprising, but it happens only once.





english
français
MGB Technical

Classic car meetings
Home

How to find spare parts ?
History 1997-2001

History 2002-2006