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Re: SU fuel Pump AUA66 (points) Overhaul Guide
Posted: Thu Feb 06, 2025 4:07 pm
by svenedin
myoldjalopy wrote: ↑Thu Feb 06, 2025 3:58 pm
With regard to the pump being 'fried', I note (as did Phil): " The results are even more severe if you have an all electronic pump."
Also: "To prevent unintended stopping of the SU fuel pump as a result of clogs, either on the inlet or outlet side, keep your fuel system clean and free from rust and sediment."
I suspect the latter in particular is a common problem with old cars. It happened to me out on the road once and I got home by blowing back down the pipe to the tank. To address the issue, I upgraded the old 5 gallon tank to a new 6.5 gallon one.
Yes I have had the same problem. The car would not run (fortunately at home). Quickly diagnosed no fuel. The metal fuel line to the tank had become blocked and I could not unblock it. In the end I replaced the entire fuel line AND the tank. I could probably have had the tank repaired but it had so much rusty yuk in it that I bought a new one instead. I didn't burn out the pump because I noticed it struggling desperately and getting hot.
Agree the point about the electronic pumps being more fragile.
Over the Winter, when my car does get used but not much, I add a fuel stabiliser/corrosion inhibitor to the fuel. I cannot really say if this actually works but it makes me feel like I'm doing something....
Stephen
Re: SU fuel Pump AUA66 (points) Overhaul Guide
Posted: Thu Feb 06, 2025 5:11 pm
by myoldjalopy
"Over the Winter, when my car does get used but not much, I add a fuel stabiliser/corrosion inhibitor to the fuel. I cannot really say if this actually works but it makes me feel like I'm doing something...." Peace of mind!
Re: SU fuel Pump AUA66 (points) Overhaul Guide
Posted: Sun Feb 09, 2025 10:51 am
by geoberni
svenedin wrote: ↑Thu Feb 06, 2025 3:04 pm
Some more stuff I have learned about these pumps.
If the inlet to the pump is blocked, the pump stalls with the points closed. This can lead to the coil overheating quite quickly. This can cause the "swamping resistor" to burn out. There is no way of knowing this has happened to the pump just by looking at it. Once the blockage is released the pump will still work but it will then go on to destroy points for evermore because the swamping resistor is destroyed.
I do not know when SU stopped using a swamping resistor or even if they did stop using it. Taking a coil out is not something that I would do. This might explain why some owners have enduring problems with a pump no matter what they do to try to repair it. Just a thought.
https://www.dbraun99.com/Dave%20DuBois/ ... _Myths.pdf
Stephen
A most interesting attachment, firstly because I did not know of the Swamping Resistor inside the coil and secondly for the photo of the Coil. I've wondered how they were assembled...
I note there is no mention of how to detect the failure of the Resistor
, I shall have to look into this more, to find out specifics of the overall resistance values.
Re: SU fuel Pump AUA66 (points) Overhaul Guide
Posted: Sun Feb 09, 2025 11:31 am
by svenedin
geoberni wrote: ↑Sun Feb 09, 2025 10:51 am
svenedin wrote: ↑Thu Feb 06, 2025 3:04 pm
Some more stuff I have learned about these pumps.
If the inlet to the pump is blocked, the pump stalls with the points closed. This can lead to the coil overheating quite quickly. This can cause the "swamping resistor" to burn out. There is no way of knowing this has happened to the pump just by looking at it. Once the blockage is released the pump will still work but it will then go on to destroy points for evermore because the swamping resistor is destroyed.
I do not know when SU stopped using a swamping resistor or even if they did stop using it. Taking a coil out is not something that I would do. This might explain why some owners have enduring problems with a pump no matter what they do to try to repair it. Just a thought.
https://www.dbraun99.com/Dave%20DuBois/ ... _Myths.pdf
Stephen
A most interesting attachment, firstly because I did not know of the Swamping Resistor inside the coil and secondly for the photo of the Coil. I've wondered how they were assembled...
I note there is no mention of how to detect the failure of the Resistor
, I shall have to look into this more, to find out specifics of the overall resistance values.
Yes. I think this is important. If say, picking up old pumps for pennies and restoring them beautifully it would be important to be able to detect which pumps have burnt out swamping resistors because they will arc badly without an external arc-suppressor.
Stephen