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MG MGA - Which SU electronic fuel pump

I am considering ordering an electronic SU fuel pump from SU in England. Which is the correct model for a 59 MGA with Negative earth.

Link to SU catalog:

It is substantially less costly than Moss.

Jim Ferguson

Jim, If you drill down from starting from the part search menu, option 2 SU carburetters, you will find the carb . Click select. Click view. At the bottom of the page, they list AZX1331EN as the electronic - negative ground - pump. I know no more about it.

My personal experience is with the points-version from Moss with the clamp diode (non-electronic) version.It has worked flawlessly for the past 8+ years for me.

C Schaefer

Thanks chuck,

I am still a little confused about their use of "Negative" in the description as being either negative powered or negative ground.

I thought I remembered somewhere that red tape on the pump body indicated it was for positive power (negative ground)systems. The catalog shows the red tape on the Positive pumps. e.g. AZX1332EP . Is my thinking correct?

Jim Ferguson


The colour banding is nothing to do with identification of the earthing. See this link in the Holden Classic & Vintage website which shows the required SU negative earth electronic pump for the MGA and also displays the various colour bandings:

Steve Gyles

Sorry, that link is not the most direct. Try this:

Steve Gyles

I have to disagree with you Steve, the color tape on the present day SU pumps does, in fact indicate the ground polarity. Red tape indicates positive ground and black tape indicates negative ground.

Jim - The pump you need is a AZX1331EN for a negative ground vehicle (negative battery terminal attached to chassis ground, making the voltage throughout the car positive) or AZX1332EP for a positive ground vehicle (positive battery terminal attached to chassis ground - the way the MGA was originally wired). If in the end, you get the wrong polarity pump, contact me at and I can walk you through changing the polarity. (Note: If yu still have your original pump, I can restore it and convert it to solid state cheaper than the price of a new pump, even from Bulen Fuel systems). Cheers - Dave
David DuBois


I have to disagree with you on the basis of the website I have linked to. It clearly shows Red banded SU pumps both positive and negative earth. It also shows blue banded pumps both positive and negative earth.

I would love to agree with you and it would appear a sensible marking, but the evidence I have seen so far does not support it.

Steve Gyles

Hi Guys,

I just installed the negative earth electronic SU pump in my roadster this past week. I did purchase the unit from Moss, #377-225, Burlen part #AZX1331EN.

According to the insert that came with the pump, a black band indicates negative earth and a red band indicates positive earth. See the attached image.


jjb Backman

Steve, I don't think that the pictures on the website are indicative of the actual pumps, just the type. E.g. there is no actual picture of the bronze bodied types.
Neil McGurk

Neil, David, John et al

Good. There is the evidence. Black mark for poor advertising by Holden. Certainly led me to an incorrect conclusion.

I searched the Burlen (SU) site for information on the banding, but found nothing. Anyone put feedback into them to put it on the website, and not just in the instruction leaflets? If not I will give them a call in the morning.

Sorry about the web links I posted not working correctly, but I presume you found the right pump from the index on the left side.

Steve Gyles

Steve - You may be referring to older pumps. Back in the days before Burlen Fuel Systems, there didn't seem to be any markings for the polarity, perhaps because the pumps back then were not polarity sensitive. Starting with the new numbering system on the pumps, all pumps with the first three characters being AZX, the pumps had a diode/resistor assembly as part of the arc suppression circuit and were all polarity sensitive. Then, starting the first of Sep. 2004, they went to using a varistor as part of the arc suppression circuit and the points style pumps went back to being dual polarity as stated in the attached flyer that came with the pump a friend recently got. Interestingly, the first high pressure pump (AUA 45) that came out had a red cap on it, which had nothing to do with polarity as it was still using only the internal swamping resistor for arc suppression. Cheers - Dave

PS. ignore the hand written notes on the flyer, there was some confusion on the part of my friend.

David DuBois

This thread was discussed between 08/03/2009 and 09/03/2009

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