Saturday, September 4, 2010

New fuel pump ordered

I was still unsure if Bugly's SU fuel pump was a high- or low-pressure pump, so I have ordered a new AUA25EN pump from "The SU Carburetter Company" at http://www.sucarb.co.uk. Price GBP-105.00 which included GBP-25.00 postage. I added a replacement cap for the broken one on Bugly, plus three filter plug fibre washers too for a further GBP-3.90. All up, A$192.00 which I though was OK, and cheaper than I could have bought it in Australia. The AUA25 is the standard pump, but the AUA25EN is (E)lectronic as opposed to the normal contact type, and is (N)egative earth.

What worried me was that it looked like the carburettor had been flooding in the past, and this is a sure sign of an incorrect high-pressure pump fitted. The SU high-pressure pumps are designed to be fitted just outside the fuel tank, and require the higher pressure to pump the head of fuel to the carburettor. The low-pressure pump is designed to be mounted within 150mm below the carburettor, and therefore require a much less delivery pressure. They are 'pullers' rather than 'pushers'.

If the high-pressure pump is fitted at the carburettor end, there is a danger of over-pressurising the carb with fuel, resulting in flooding and a potential for fire. This I certainly DON'T want! So I erred on the side of caution. If one day I check the pressure on the existing pump and find it is low-pressure, at least I'll have a spare.

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