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SU Pump with Optics

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RAC68

RAC68

Darth Vader
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Sorry to be bringing up fuel pumps again. Having transistorized my main and spare AUF300 with the modifications presented by Dave Dubois, I did a little research and learned that Dave is now using an optical trigger circuit on all his SU pump rebuilds. This optical circuit eliminates potential failures from the inability of transistorized tungston points to burn off point oxidation that forms during long periods of inactivity and, according to Dave, could extend the life of the pump indefinitely. It seems to me that this approach may be exactly what is needed to put long term reliability into the SU pump and was wondering if anyone had further information on the optical trigger approach.

Ray (64BJ8P1)
 
Ray, Thaks for this interesting post. Reliability is a big issue for me. When I was 19 I didn't seem to care about lying in the dirt on the side of the highway fixing a failed fuel pump. Now that image seems a bit scary. Do you have contact info for Dave?
 
My 2 cents worth,

The most reliable trigger would be a magnet exciting a hall effect trigger / transistor.
This is how the petronix ignition trigger works.
....
The next most reliable trigger is the optical trigger which is
no more than a " flag " interrupting the space between an LED and a photocell trigger.
..
The surface of the LED or photo cell can get dirty or water drops can condense on them and then it will stop working.
...
The new electronic conversion kits that SU sells for the old fuel pumps use the hall effect trigger. That is probably the most reliable design to use under the car in the fuel pump.

https://www.sucarb.co.uk/ProductCategory.aspx?ParentId=16&C=151

Ed
 
Ed_K said:
My 2 cents worth,

...

The new electronic conversion kits that SU sells for the old fuel pumps use the hall effect trigger. That is probably the most reliable design to use under the car in the fuel pump.

https://www.sucarb.co.uk/ProductCategory.aspx?ParentId=16&C=151

Ed
Click to expand...

I did a couple conversions to the kits with less-than-satisfactory results (followed instructions to the letter). Heard later that the early kits had problems, likely resolved by SU by now. I have a 'factory' electronic SU in my BJ8--20K+ miles with no problems and going strong (but I still carry a points-based spare).
 
Ed,

My initial intention was to install the SU electronic kits on my pumps but researching the conversion provided a number of negative responses. This indication was mirrored by a number of users who purchased the SU electronic pump from Moss.

My alternative, at the time, was to implement Dave’s transistor modification to prolong point/pump longevity. The side effect of Dave’s transistor approach turned out to be that the lower power passing through the points is insufficient to burn off the tungston oxidation that forms over periods of inactivity.

I have been using an Allison/Crane XR700 optical electronic ignition for the past 20 years without a problem and if I get 15 years out of the pump I will be too old to care. As with Legal Bill, although I enjoy working on my Healey as a hobby (my father always said that the difference between a hobby and work is…if you have to do it…its work), I would rather not play on the side of the road.

Ray (64BJ8P1)
 
Terry Ingoldsby kindly responded to my inquiry on his development of an optical circuit for the SU Pump with the following electronic schematic (https://docs.google.com/viewer?a=v&p...E4&hl=en_US).

Terry’s goal was to reproduce more closely the original points mechanism - which turns the solenoid on and off based on position. He indicated that "Dave's optical trigger only turns the solenoid on. Then, he uses a timing circuit to provide a fixed width pulse. The duration of the pulse is such that it is about right to pull the diaphragm to a fully retracted position. The solenoid then turns off and is not reactivated until all the fuel has been expelled from the chamber and the optical sensor again triggers the solenoid. The circuit apparently works very well.”

Although a wire rap version has been made to fit within the confines of the SU pump head, a printed circuit would be a more convenient and elegant alternative. Terry is interested in moving forward and is looking for someone with the interest and facility to create a printed circuit layout and board. Please let me know if anyone has the interest and facility to aid Terry in moving to this next step.

Ray (64BJ8P1)
 
Legal Bill said:
How can you tell if your pump is electronic? Mine was purchased by someone else, so I'm not sure what he bought.
Click to expand...

If the pump is a new edition the absence of the step on the back cover is an indication and they will have a red band around the midpoint of the body.
 
[Part Number: EPK12N]
Electronic Pump Conversion Kit Negative Earth 12 V
By Burl en has always used a circuit board?????-----Keoke
 
Legal Bill said:
How can you tell if your pump is electronic? Mine was purchased by someone else, so I'm not sure what he bought.
Click to expand...

My electronic SU makes a thumping sound as opposed to a points pump which makes a clicking noise. Also, I believe the 'factory' SU electronic is a different part number than the points model (check the SU/Burlen website).

Otherwise, you'd have to pull the cap off the pump to be certain; esp. if it's a conversion.
 
A while back, I indicated that I had installed Dave Dubois’ transistor modifications on my primary and stand-by AUF300 SU Pumps and encountered the tungsten oxidation problem. In an e-mail received today, I was surprised to learn that Dave had created this approach 30 years ago and, for the past 20 years, has been trying to kill any reference to this plan as a result of the problems I had encountered. He also indicated that, at present, he is using an optical triggering approach on his rebuilds and seems to have no interest in providing a DIY kit as he feels the potential for installation error is too great.

For those interested, Dave provides his rebuild service between October and May.

Ray (64NBJ8P1)
 
Keoke said:
Legal Bill said:
How can you tell if your pump is electronic? Mine was purchased by someone else, so I'm not sure what he bought.
Click to expand...

If the pump is a new edition the absence of the step on the back cover is an indication and they will have a red band around the midpoint of the body.
Click to expand...

I have a new this year electronic SU pump and it has blue tape with the SU logo every few inches . My pump is negative ground.
.....
This brings up a good way as any to tell what you are looking at on a web page of SU pumps.
If it is an electronic pump, it must be identified and sold as
either a negative or positive ground pump. An electronic SU pump CANNOT be connected either way.
If it is a points pump, it may be listed as " works with either polarity ".
I don't know but I suspect the red tape may mean positive ground since my negative ground pump has blue tape around the cover.

Ed
 
Hi Ray,
I bought an electronic SU pump about a year and 1/2 ago. It worked great for about 1 year. It failed in my driveway ! That has to be some of the best luck I ever had ! Back to the
pump story ...
The last time that I had taken the car out before the pump failed, I had to drive for a long time in a cold steady rain.
After the pump failed in my driveway and I removed it from the car and took the lid off to see if I could find out what fried,
I found a lot of water that had apparently either condensed or had somehow gotten under the cover. All of this water must have shorted out something on the printed circuit board. Our usual supplier with the two year guarantee replaced it with a new one without any question.
When I installed this pump, I added a couple of 6 inch long rubber hoses and cable tied them so they opened in a downward
direction. This was my attempt to make certain that if any water splashed up to the ends of the vent hose or the fitting without the hose that the water will have a hard time getting in under the pump cover. I don't know if this is actually helping anything.
I am not happy with the single point of failure that the standard single ended SU pumps create. The original pump failed and I barely made it home by hammering my fist on the back wall of the car under the passenger side seat until I got home. Then the electronic pump failed.
....
I want to keep the originality of the SU pump but I think the only way to be safe is to have a double ended SU pump installed with a switch to run either end or both ends at the same time. A double ended pump would not require any butchering of the fuel lines.
The only other alternative is to add a 2nd pump inline with the single ended SU. This could be one of those facet cube shaped pumps. That would require some modification of the hard fuel lines.
A double ended SU pump could be either points or electronic type since it has 100% redundancy built in.

Ed
 
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