MGB: Opto-triggered SU fuel pump - its alive!

For the past while I have been working on a new electronic circuit to replace the points in the SU fuel pump. I know there are several circuits out there. There is the Burlen circuit which triggers using magnetic sensors and Dave Dubois' circuit. While both are very effective, they do not operate in the same manner as the original points-based system.

I wanted to create an electronic system that had separate high and low switching positions (as the hysteresis-based points do). I managed to come up with a scheme using two optodetectors. One detects when the diaphragm has dropped and engages the solenoid. The solenoid remains activated until the other sensor detects that the diaphragm has been pulled back to the top position - it is then deactivated and remains so until the diaphragm once again drops. Since all of the sensing is done optically, the system should last almost forever.

The circuit has now been tested and found to operate properly. However, the prototype is probably not sufficiently well constructed to put on the road. That would require creating a printed circuit board and improving the layout and construction. My question is whether there is interest in such a circuit. I am not particularly interested in making this a commercial venture - but rather having someone use the circuit. I'll also say that this project couldn't have gotten where it is without the support of Mr SU fuel pump himself (Dave Dubois).

Comments?

P.S. I'll try and post a picture tomorrow.

I hope it still clicks. If it doesn't click then it won't give me that warm, fuzzy feeling every time I turn on the car. Then again I'm not normal... :drinking:

Terry - "While both are very effective, they do not operate in the same manner as the original points-based system."

My set up does operate in the same manner as the original points-based system because I use the original lower toggle to carry the interrupter vane. The difference between my triggering system and the one you have designed is that mine is still afflicted by the mechanical wear of the original toggle.

Congratulations on getting your trigger working. I'm looking forward to seeing your pictures. I haven't answered your e-mail yet as we got back late from visiting our daughter and new grand daughter today.

Steve - "I hope it still clicks."

If you have heard the Burlen Fuel System all electronic pump, Terry's system will sound the same. It will still have the characteristic ticking, just a bit softer than than the points pump or my pump because it does not use the lower, mechanical toggle, which produces a harder sound.
Cheers,

Is the view worth the climb? I bought a cheapy quiet pump 30 years ago and it's still working. I cant imagine it is worth the time and expense to use this approach, even though it is lovely.

For those wishing to maintain the original equipment look but with modern technology your optical solution is perfect. I'd be interested in buying the opto-triggered parts.

Tim

That is definitely cool, Terry.

Very cool. It's nice to sometimes see extremely modern technology be used on these cars. It's an exercise for the brain, and I love it.

Terry - No corrections, just some clarifications.

"...but it uses (part of) the mechanical points mechanism - it is not fully electronic. Is this a problem? Not really - the portion of the points that Dave uses will probably outlast the car - and no current is carried by conventional points so they will never burn ...Dave's mechanical/electronic design - the points will outlive you."

See the attached photo. The contacts have been completely removed from the toggle, which is why I am careful to refer to it as the lower toggle, so no one get confused that there might be points still in use (I had that situation with one individual when I was using a magnetic reed switch for triggering). As for not being fully electronic - maybe, even with the BFS all electronic, the magnet is carried on and mechanically moved up and down by the travel of the mechanical diaphragm spindle. This gets to be a shaded area - what is truly all electronic and what is electromechanical. I would suggest that all of the pumps would be classified electro mechanical, but that may be drawing too fine a line. I refer to my modification as solid state to differentiate it from the all electronic version produced by BFS. I think that sine Terry is using a J-K flip flop as part of his circuit, we refer to it as a digital fuel pump - that's how the big corporations would market it:bouncing:

As for the ticking of the pump - the distinct ticking sound made by the SU fuel pumps is what I call a hard ticking (for lack of a better description) is produced by the lower toggle striking the pedestal on the upward transition and the top of the coil housing on the downward transition. There is also a softer ticking (masked by the sound produced by the toggle) that is produced by the diaphragm armature striking the core of the coil at the top it travel. This is softened by a disk of rubber on the top of the armature. The BFS all electronic pump and Terry's digital pump is going to have just the soft ticking of the armature against the coil core. I would be willing to bet that unless a pump with the toggle in it and one without the toggle were run side by side, that less than 10% of people using a SU pump would be able to differentiate between the two - I can because I have the pumps running on my test stand all the time and I suspect that Steve S. would because of his attention to detail.

Scott - "Is the view worth the climb? I bought a cheapy quiet pump 30 years ago and it's still working. I cant imagine it is worth the time and expense to use this approach, even though it is lovely."

Different strokes for different folks. You are absolutely correct, there is no compelling reason to not use the cheap Facet or Carter pump that will work perfectly well as a replacement for the SU and for a person with a practical bent such as you that is definitely the way to go. So would replacing the antiquated B series engine or the four speed transmission, with or without an overdrive with a modern engine or a five speed transmission from any number of newer cars that are pushing the envelope of technology. the rear suspension can be (and has been) replaced with modern 5 link suspension and the old lever shocks are replaced with modern tube shocks. This is all well and good and I enjoy reading about all of it in the Enjoying MG magazine from the MG Owners club, but when does an MG with all of these updates cease to be an MG? I don't know the answer to that. I do know that when I suggest that customers might want to consider that alternative when the price of restoring their pump and converting it to solid state is going to run especially high due to excessive damage and is going to take 5 weeks for me to do it because of the backlog of work that I have, they most often say that is ok, I want yo to restore my pump. I had to outright refuse to do two pump for a customer because it would have cost him more to restore them than to purchase new ones directly from BFS before he would take the more reasonable route. Two years ago a gentleman from Whales paid me nearly $1000 to restore four pumps for prewar Bentleys and Rolls Royces although I suppose that a Facet or Carter pump would look out of place on the side of the engines where their pumps mount. My point is that there are a tremendous number of people out there who want the original everything on their vintage car, and would like for it to be reliable. BFS, Terry and I can provide that with our respective modifications and these people are grateful for that (I know one gentleman who refuses to permanently mount a Facet pump on his MGB to be used as a backup pump - his choice).

So there you have it. Is what BSF, Terry and I are doing practical? It is for the person who wants to keep original looking and operating equipment on his/her car. For the people who are more concerned about function at lower price, it probably is not. For BFS, this is their business. For me, it is a retirement business that I enjoy doing. For Terry, it is for the challenge of doing something differently and perhaps a bit better (and I hope to someday to convince him to become a competitor - it would be a real boon to British car owners on the north side of our boarder with Canada).
Cheers,