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MG TD TF 1500 - TF Fuel Pump


Hi everyone,

Can somebody help in identifying the correct fuel pump for a 54 TF. I know it has to be a pressure pump. The pump which I removed from the car has ' SU Pressure pump 12v ' moulded into the bakalite cap, the overall length is 135 mm, the pump body says SU Part No. 4080, and a label AUB154.

I have acquired another pump which I am told is for a TF and is longer, 155mm overall length and all other markings are identical except for the label AUA 67.

Both pumps are faulty and I want to repair the correct one.

Finally I am told that an MGB pump will do the job, is this correct.

Thanks

David Tinker
David Tinker

David,
The correct fuel pump for TFs from chassis number 1501 is AZX 1332 (AUA 56) high pressure-positive earth. If you have negative earth the referrence is AZX 1331.

TFs prior to chassis number 1501 use fuel pump AUA 25 low pressure.

Dave
David Kalp

Seeing David K's reference to different part numbers for pos/neg earth cars makes me wonder if my AUA 25 low pressure pump is connected correctly.

It's working fine and I don't recall any mention of swapping connections when goint to negative earth.

Are pumps really polarity sensitive?

jt
John Thomas

SU fuel pumps have a capacitor [condensor] or a diode [later models] to limit the voltage surge that results when the points separate and the circuit becomes open. The coil that operates the diaphragm has a large inductance, and without the cap or diode, the points would burn up pretty quickly.

Diodes and most capacitors for automotive applications are polarity sensitive. Theoretically, you could reverse the leads on the cap or diode and then the pump would run fine on the reverse polarity, but there may be other reasons that prevent you from doing this.

MB
Mark Barrington

If I am reading my SU catalogue correctly, AUB154 was replaced by AZX 1331 & 1332. These are the same pumps as listed for the ZA/ZB Magnettes.
Henry Buckeldee

Further to last message, the MGA also uses AZX 1331/1332. The MGB pump is from the AZX 1300 series of pumps, and will have very similar characteristics such as suction lift, delivery head, capacity etc. The exact difference I could not say.
Henry Buckeldee

Early TF's had the fuel pump mounted on the fire wall the same as TD's which I belive was a low pressure version. Latter models had a high pressure pump mounted on the chassis near the fuel tank. This is difficult to get at and water sometimes gets in if not sealed properly. I have installed a diode in reverse polarity across the pump coil. This stops the back EMF voltage sparks which pit the contacts. The pump has been going for 15 years without a problem except cleaning the filters occasionally.
J Davey

How about a diagram of the conversion together with a spec of the diode so we can give it a try?
David Tinker

David - Contact Burlen Fuel for the diode to be used with the fuel pumps. You will also need to get a stepped cap to make room for the diode. Burlen Fuel web site is:
http://www.burlen.co.uk/
Good luck - Dave
David DuBois

This thread was discussed between 17/04/2002 and 06/05/2002

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.