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MG MGB Technical - Solid State Fuel Pumps!!!!!

Hey people!!

I know there is a lot of stuff in the archives about these but I just need a straight yes or no for the following question.

Do I need to fit a pressure regulator when I fit a solid state fuel pump, or is it just a straight swap for the old pump?

Thanks for your help and wise MG responses!!

Adam
A J Cooper

If it is the S.U. electronic solid state one it is a straight swap. Did it last year and am pleased so far on my 69 Roadster. Now, if it is not that one you need to be sure the pump is pumping the right volume/pressure level regardless of solid state or not.

JTB
J.T. Bamford

Depends!!!

A solid-state version of the SU designed for the MGB does not need a presure regulator. But there are other makes of solid-state pumps out there that deliver a higher pressure than the carbs can take and do need a regulator.

My V8 came with a solid-state SU-type pump, it gave me so much troble that I swapped it for a refurbed points-type which has given no more trouble. The benefit of the points type over the solid-state is that they usually give you warning of impending points failure, and can be kick-started by giving them a thump. With a solid-state you stand no chance, as I found out.

My 2 penn'orth.
Paul Hunt

Adam.
You may as well fit a filter king at the same time. Then you get a regulator for the pump and a decent fuel filter system.

I've got a solid state pump and filter king on my car and you would be welcome to see how its setup. (Although I run a weber not SU's)

you should be able to see my e-mail on this page!?
T Crossley

An answer is YES if you have an aftermarket solid state fuel pump which produces a range of pressures up to, say 4-5 psi. An SU will really only tolerate about 1.5-2.5 psi gladly, and anything above that range sometimes with problems.

The answer is NO if you use one of the SU pumps mentioned above.

Some problems encountered even with the OEM type pump come from worn out or crudded up float valve needles or mis-set ones and loose/leaky ones. Any pump deserves half a chance by the rest of the system being set up as it should.
Bob Muenchausen

I changed to a Japanese solid state pump and needed a regulator but soon became annoyed with the noise.

I bought a new SU electronic last year and then the problems started. Once I was sure it was the pump the Aussie distributor exchanged it without fuss and I now have no problems.

I understand the SU electronics are a lot more reliable than they used to be.

If I had my time again I think I would have stayed with the original pump.

Nowadays, I always carry the noisy Japanese pump and regulator with me, just in case!

FWIW
Ian Buckley

Thank you so much for all your MG wisdom.

Mr Crossley, I have your email address and may take you up on the offer of having a look.

Just sent the cheque for the pump, so should have it in the next week or so.

Thank you all for your help, will let u know how i get on!!

Adam
A J Cooper

Another option for the fuel pump solution is one from a Mazda. I had to replace one on my Mazda 1800 (four cly) and the pump looked like a SU pump on the outside but they did a much better job on designing the contact points. I installed one from some 1300 cc model on the midget I rebuilt and it has worked very well with SU's and Weber. It is also quiet! I may have some photos somewhere. Jeff
Jeff Pintler

Regarding the SU look alike pump used on the Mazda, they wear out and quit working at about the same milage as the SU pumps do. As a matter of fact, so do the little square, run all the time, make a lot of noise pumps made by fawcet. How do I know? I have had two Mazda trucks, one using the SU look alike and one using the Fawcet pump. Both pumps died somewhere between 50,000 and 75,000 miles. Face it, all electric fuel pumps are electromechanical devices that have a finite lifetime. The pump that came with the MG you bought, has probably already seen most of it's life pass before it's eyes by the time you got interested in the car (unless you bought the car new, in which case the pump is at least 24 years old). All of these pumps are going to eventually die and leave you stranded on the road, live with it and carry a spare 9or better yet, install the spare in line with the original pump and wire the two pumps through a switch. For more information on the SU fuel pumps (but not on how to make them last forever) see my article at: http://www.custompistols.com/cars/articles/dd_su_fuel_pumps_101.htm
Cheers - Dave
David DuBois

David,

Following up your comments, if you stick OE rather than electronic, a hammer tap can usually get you home.

Paul
Paul

Or more importantly with electronic you usually can't, as I found out. I have gone back to a pointy pump.
Paul Hunt

Paul and Paul - If the all electronic units are set up properly, one should never have to tap the pump. That said, I worked with electronics for too long (39 years prior to retirement) to ever trust the bloody stuff, so I have a spare installed where it is only a switch throw away from getting me home. Electronics is great stuff, but it is not a cure all (yes, I know there is someone out there who can say that their 50 year old all electronic pump has never missed a beat). Considering that my career was spent repairing some of the best, most sophisticated electronics systems the US Navy had to offer, I would be the last one to maintain that electronics is infallable. That Infallable stuff kept a roof over my family's heads and food on the table for 39 years.

Paul H. I have run a fuel pump that I modified to solid state, using a magnetic reed switch and magnet as triggering for many years. Recently, I modified the pump using one of Burlen Fuel's Hall effect circuits so that I could see how well it works. I have only been running it that way for about 6 months, so the jury is still out. Our upcomming trip to Southern California will be more of a test for it. The only difference that I have noted so far is that the Hall effect circuit causes the pump to run just a bit more quietly, otherwise there is no change in any of the pumps parameters.
Cheers - Dave
David DuBois

David,

Only 30 years for my pump, but are you saying electonic pumps never breakdown or should never which in reality is quite often?

Paul
Paul

Paul - I believe that the electronics industry would like us to believe that anything "all electronic" will never break down. The reality is that they break down at about the same rate as anything else. As I stated in my post of 7 Feb., they are an electromechanical device and subject to wear like anything else. I really think that the original points style pumps probably last as well as the all electronics do until the first break down. After that, it is up for grabs, because if they get repaired it is usually by the owner, the expertise of which can vary from the very compentent to the ones that should never be left alone with a screwdriver in their hands. Add to that some of the poor quality parts that are sold (not the parts that come from Burlen Fuel - they are top quality). The other thing that affects the pumps is that if they are ever stopped in a current on condition, such as when there is a clog on the inlet side of the pump and the power is left on for any period of time (which is often the case), the swamping resistor inside the coil housing is burned out and since it can't be seen, nobody knows that it is gone. Since the swamping resistor is part of the arc suppression circuit, the result of the resistor being burned out is that there is excessive arcing at the points from that time on and all of a sudden the owner can't get any longevity out of a set of points. We are then regaled about how SU fuel pumps are right up ther with Lucas electrics and everyone should use this or that aftermarket pumps.

Getting back to the all electronic pumps, if the scenario above (failure in a current on condition), if the power is left on for any length of time, the results will be disasterous. With continuous curent flowing through the power transistor (actually a field effect transistor), it will eventually overheat and destroy itself, probably burning a hole through the circuit board at the same time. As I remember, the Hall effect circuit modification kit to repair this situation is in the order of £39 - considerably more than a set of points.

So why do I modify pumps to solid state? I think that they are probably more reliable in the hands of most owners who are not real compentent with electrical devices. I have found that they are much less inclined to mess with something that is called solid state or all electronic than they are with something with a "simple" set of points in it. It has been my experience that if something goes wrong with a pump that I have modified, people will generally send it back for me to take care of. I do all repair work under warrentee unless there is evidence of tampering, which is very seldom.
Cheers - Dave
David DuBois

This thread was discussed between 03/02/2004 and 09/02/2004

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