The 'E' Type Forum

Hi I have a new fuel system with correct modern SU pump. Should it need priming and do I need a pressure regulator with filter at front.

No and no.

If you're worried, disconnect the line between the fuel filter and the carbs and let it run for a few seconds to clear any bubbles.

The fuel system will clear itself of any air in the lines via the vent tubes at the top of the float chambers. No need to disconnect the fuel line on initial use of the new fuel pump.

And no pressure regulator needed as the SU fuel pump will provide fuel pressure in the correct range.

bitsobrits wrote: ↑

Thu Jan 16, 2025 1:44 pm

And no pressure regulator needed as the SU fuel pump will provide fuel pressure in the correct range.

Please be careful, as it has been well documented within this forum, that SU pumps push out above the recommended pressures. A filter king is perfect to prevent fuelling over pressure and potential fire risk. I had 2 new SU pumps last year and both were tested, on fitment, and both were over 3PSI and can pulse higher.
Also, some facet pumps can push out in excess of 6PSI.

Read the following:
viewtopic.php?f=9&t=164&p=167738&hilit= ... ng#p167738

viewtopic.php?f=3&t=14130

I think it would be more correct to say "some" SU pumps put out too much pressure, so one needs to use one that is specific to the car. My SU pump, from Burlen, as specified for the E-type, produces just over 2.5 psi on my test pressure gauge, measured after the fuel filter. 1.5 to 3.5psi is a frequently quoted preferred range for SU carbs in general (google it), with 5psi generally considered too much. There are thousands of E-types running around without pressure regulators, because they are not really needed. But nothing wrong with fitting one if it makes one feel better. It's just another potential leak point that will be subject to future mis-adjustment.

And the comment about Facet pumps is not relevant as the OP already has an SU pump. FWIW, Facet also makes suitable pumps that put out 1.5-4psi (PN 60104-I use one on my Lotus Elan).

Also on the subject of fuel pressure, it is most beneficial to use a proper low pressure range gauge. Using a gauge where 2-5psi is at the low end of higher range (like 25 or 50psi max) won't do. You need a gauge with a maximum of 10 psi or less to get a more accurate read.