Fuel pump polarity

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67-2door
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Fuel pump polarity

Post by 67-2door »

My Minor has previously been converted to negative earth and has a Facet electronic fuel pump fitted, I was thinking of getting an original SU electric pump as a back up because they're serviceable unlike the electronic one.
Can the original SU type be run on negative earth or would I have to convert back to positive earth to use it?
Thanks.
Neil.

Sidney'61
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Re: Fuel pump polarity

Post by Sidney'61 »

The original pump works with both positive and negative earth.
Andy W____________1961 2-door 948cc (Sidney)_____________1963 2-door 1275cc (Emily)_______

billlobban
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Re: Fuel pump polarity

Post by billlobban »

Modern SU fuel pumps are indeed dual polarity
67-2door
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Re: Fuel pump polarity

Post by 67-2door »

You say "modern" SU fuel pumps are dual polarity, does that mean 1960's originals are not?

billlobban
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Re: Fuel pump polarity

Post by billlobban »

If I remember correctly (I could be wrong) SU sold positive and negative pumps at one time but for many years they have been dual
PSL184
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Re: Fuel pump polarity

Post by PSL184 »

The ONLY pumps that are polarity sensitive are the electronic ones. Original SU pumps (still available new today) will run in either direction without problems, although, it may be wise to change the points if you reverse the polarity of an already used pump, however, I never have and have not had any problems.....
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billlobban
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Re: Fuel pump polarity

Post by billlobban »

PSL184
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Re: Fuel pump polarity

Post by PSL184 »

Single type electric pump (Standard on a Minor) http://www.sucarb.co.uk/TechnicalDetail.aspx?id=53 is not polarity sensitive. Other pumps (dual type) as per your link may well be, but not used on a Minor....
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bmcecosse
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Re: Fuel pump polarity

Post by bmcecosse »

An old pump will be fine on -ve earth. Clean or renew the points - and try it out before carrying it as your spare. In fact - I would fit it - and carry the 'foreigner' as the spare!
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