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MG Midget and Sprite Technical - SU Fuel Pump

Great forum. On the SU fuel pump are what I assume to be two vent fittings; one on the back of the diaphragm and another in the area of the solenoid. Where to (and how) did these vent originally? Thank you in advance.
TS Smith

There should be a plastic pipe on each of these vents and they are connected to two T-pieces which dangle from inside the boot (trunk). If you look into the boot there should be two holes in the floor near the front. A plastic T-piece is put into the holes and the pipes are plugged on to the bottom of the T.

In this diagram http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=1420 they are parts 60 and 63.
Mike Howlett

Thank you Mike. The ends of the "T"s are left open inside the boot? I assume these are routed "inside" only to stay clean.
TS Smith

that is correct, just routed into the boot to keep the air that goes into them relatively clean
Norm Kerr

See the article, SU Fuel Pump Vents in the SU Fuel Pump Articles section of my web site at: http://homepages.donobi.net/sufuelpumps/ This article is written to the MGB, so there may or may not be a hole into the trunk area. If there is no hole, you can either drill one (put a 'T; on the end of the tubing to keep it from slipping out) or just route it to the highest spot under the car and fasten it such that the end points downward. Cheers - Dave
David DuBois

It is a good point about the way these vents are piped in. I rather think it was an early effort at safety. It allowed the electrical spark from the points in the pump to vent into an area that was considered safe and free from petrol vapours.
Robert (Bob) Midget Turbo

Bob - It really had nothing to do with safety - rather it is relieving pressure from the back of the diaphragm so the pump would operate freely. Cheers - Dave
David DuBois

Yes I agree slightly Dave it does allow the coil and diaphragm to "breath"
But equally you have a very energetic spark being created that is not the kind of thing you want near petrol vapours. Thus this is allowed to breath into an area that is safe.
Bob Turbo Midget England

This thread was discussed between 13/06/2011 and 14/06/2011

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.