www.jec.org.uk

Good morning all.
I've just re-joined after many years of absence. The project is to put my 420 back on the road.

Has anyone got any technical views/experience/advice on replacing the twin SU fuel pumps on a ’69 420 with electronic versions please?
I’ve been given a ‘lead’ to look at FuelFlow ECCO 15LM12 SU Fuel Pumps, they seem to fit the bill and the pump pressure matches the original electro/mechanical SU spec, with 3-4 PSI and a flow of 1.5 litres a minute.
Stating the obvious, the 420 is negative earth but these can deal with either polarity.

I was also advised to look out for back flow under pressure from one tank to the other. To my knowledge there’s no non-return valves on the original setup, so I thought maybe I'd just fit a couple of small in-line ones into the fuel lines after the pumps?

What about pressure regulators, has anyone felt the need to fit these?

Any sensible views would be very welcome please. Thanks in advance!

Cheers, Mac Booker.

Hello Mac,

I'm not really familiar with the 420, but is there seperate pumps for each tank? If so the pump has built in check valves effectively, both suction port and the discharge port valves are check valves. Certainly no harm in fitting extra but I don't think it's necessary. Also you shouldn't need a pressure regulator of these pumps have the same output pressure of the original S.U.?

Alec

You may have already spoken with them Mac, but Burlen Fuel systems (01722 412500) should be able to give you the advice you need (and supply the pumps if you decide to go with SU again).

Robbie

Thanks gents!

Well I bit the bullet and replaced both the failed mechanical SUs with electronic fuel pumps.
I opted for the ECCO 15LM12v ones as mentioned above.
Very straightforward. The existing banjo fittings, bolts and fuel lines fitted into the new pumps and the existing mounting brackets clamped them into place in the recesses over the fuel tanks. I had to fit some spade connectors to the cables from the new pumps but they simply clicked into the existing ‘live’ and ‘earth’ connectors of the existing electrical cabling.
So far so good, no leaks I that can see or smell and the re-assuring click-click of the pumps when I turned on the ignition until the fuel bowl filter and carbs are full.
A couple of big thank-yous:
Aaron Goldman of Classic and Prestige Auto Services Pty. Ltd, Brisbane Australia (via the Facebook group ‘Jaguar Customising Forum’) for the advice and recommendation of which pumps to look at and also Graham Wilkinson, Managing Director of FUELFLOW™ Solutions Ltd in Waikino, New Zealand for the very sound guidance on how to fit the pumps made by his company.