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MG Midget and Sprite Technical - SU Pumps

Is it worth paying the extra to get a SU Electronic fuel pump instead of the SU pump with points?
R Mcknight

Depends on how often you drive the car.

If it is driven a lot points should be fine as they don't stand long enough to oxidise.
If driven only a little the electronics should have the advantage here
Onno K

And that depends on how you define how often you drive it.

I left mine for 2.5 years without driving it, and the points were fine. Turned on the ignition, and it started ticking. I know others seem to have a problem with points, but in 38 years, I didn't have a problem, until the pump had been in over 20 years.

The advantage of points, is that if you do have a problem, you can fix it by the road. You can't with electronic. Given that a points SU pump often lasts 20 plus years, I just don't see the great advantage of electronic.

But this is one of those tea/coffee issues.
Lawrence Slater

Do you have an existing SU points pump? If so you can get spare parts from Burlen Fuel Systems, Leacey etc. they can be serviced and rebuilt.

Cheers
Mike
M Wood

Id recommend the points there very robust and wont short out because of an electrical fart...you can even add in a lucas condensor to make it unreliable

Prop
Prop and the Blackhole Midget

I'm with Lawrence, and yes, Mike's suggestion to overhaul is certainly viable.
We have been using a 25V bi-directional diode for spark suppression, presents a short sircuit to anything over 25V in either direction so there is very little spark and the points last very much longer. (Sorry Lawrence, it make it slightly electronic, but you can still fix it by the side of the road)
Paul Walbran

Hi Paul,
Yup agreed a diode surpressed pump can be fixed by the road side, but it means taking the end off the pump to take it out or replace it, if it's gone short cct. Most caps often go open cct. And although the points would spark more, a bang on the back seat often gets them going again. If the diode is short, you have to disconnect it.

The use of the word "electronic" is often misleading. And so it is here. The points type SU, is just as "electronic" as the tranistorised/diode type. In both cases, electrons are flowing in sufficient quantities to cause the pump to operate. The only difference is that the so called "electronic" version, uses solid state switches as opposed to a mechanical switch -- contact breaker.

A diode is considered an 'active' component, and a capacitor a passive one. But both can be used to suppress the spark at a switch, and both are electronic, since they are controlling the flow of electrons at the contacts.

Pedantic perhaps. But the point is(pun intended :) ), that using solid state devices, makes the SU pump less servicable, because you can't bang the back seat to get you home, and I would argue, no more reliable than it already is using points for the switch.
Lawrence Slater

The problem with banging on the back seat is that when you get home you then forget to do anything about it, so next time out the same thing happens and you mutter about how unreliable the pumps are.

But it's a very handy feature, got me home on more than one occasion whereas alectronic dies completely.

Paul Walbran

Yup agree with you there. I banged on my back seat for a year once, until banging didn't work anymore. But I was able to drop the pump, clean the points, and be on my way again. I put ned points in after that.
Lawrence Slater

Thanks for the info , Mechanical it is then!

Just wanted to fit a new pump and carry the old one on a trip overseas as a spare.
R Mcknight

This thread was discussed between 05/07/2015 and 06/07/2015

MG Midget and Sprite Technical index

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