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Update on the topic. It was indeed the fuel pump, as you all guided me towards. Final cost was three hours of labour, and the price of a new pump, at a total of £396. If I could have done it, then it would have been the cost of a pump only, which I think I could have got for around £120, but that's life, I couldn't do it, so I had to pay someone who could.
I asked for the old pump back, just for grins, so I can take it to pieces and investigate why it failed, if I get a spare moment or two to look. Could be a while, but if there's anything interesting to report, I'll post it up.
Well, I'm afraid I learned little to nothing, maybe?
Below is the assembled pump, although I have already cut away a ring of peened over metal, from the outer can, at each end. There is no easy way to get into this pump, without it being destructive. Matters not to me though, as the car is fixed, and even if I found an obvious fault with this pump, that I could repair, for use on a future occasion, I can't fit it anyway, so if paying all that money, to have it done, I would always go with brand new anyway.
Having already taken the peened over ends off, I still couldn't remove the centre, so I cut a slot along its length.
Although the can is still assembled, this made it loose enough to slide the interior out.
Below is the impeller in place.
This is what it looks like when out.
These are the brushes, looking down on them into the top of the pump. They both have good remaining length, are equal, flat, in good condition and both move completely freely.
Next is the motor core, with the commutator on top. The commutator looks clean and shiny, with little scoring, and are equally worn and level.
Next is the motor core out.
Next is the other side of the motor core.
All contacts measure the same resistance to opposite pairs, or to adjacent pairs. Not sure how else to measure it? Low values, 0.3 Ohms, adjacent, 0.5 Ohms opposite, and all consistent, however, you can see some melting on one opposite pair, where the plastic has bulged and oozed out a little at the end. I don't know if this is the failure, but it doesn't look good to me. The bigger two lumps did not foul the top or the magnets, and it spun freely, but it can't be 'right'.
Last picture is the magnets, which were not glued in place, with no evidence of glue. Maybe they just position them, and they cling, magnetically, to the outside case, more than they are pulled round internally, by torque from the motor core? Perhaps this is common, with this type of motor? There are no tags in the top or bottom that would locate them, and stop them from being able to move. Indeed, they were keen to move, and follow out the motor core, as I pulled it out.
Certainly can't help me, or anyone else, because I don't think you can get into it without extreme measures, like mine, but still, it is somewhat interesting I think.
Overall impression is that it is of very high quality, very well made, yet still it failed.
Yes, obvious heat damage. And the prime cause of modern in-tank fuel pump failure is repeatedly running the fuel tanks to near empty. The fuel pumps are cooled by the surrounding fuel. Low fuel, insufficient cooling.
So I have read, and indeed, it may well be a common cause, but it isn't the cause here. I agree it has been overheated, somehow, at some point, but not from running the fuel low, because it's not something I do. Can't say I've never done it, but my routine behaviour is never less than 1/4 tank.
Oh, I was wrong, there is a spring loaded plastic spacer to push the magnets into position. Don't know how I missed it. They can't come inwards, or move, as a result of prongs in the cap, one of which has a slot in the middle, with a spring steel spacer inside to keep it wide. I've just seen it, whilst considering reassembly, and testing, after having trimmed the bits of molten plastic away. Granted the balance will be out, but just curious now, because it seems to be electrically sound. I'll glue it together, just to make it work, using my bench power supply and then throw it away.
Well, I rebuilt it, just to see what would happen. The white part, the end with the bushes in, pushed in very tightly and held perfectly without anything to hold it in place. The opposite end, the bottom cap, over the impeller, I simply lined it up, pressed it up hard, and taped it tightly in place. I then powered it up at 5V and it ran straight away, so I increased the voltage slowly to 12.5V and it ran powerfully, and fairly quietly. I then started it at 0V, and slowly increased the voltage, and it began running at just about 2V, so there can't be too much resistance to motion. As far as I can see, it seems to work perfectly now. At this point I have not trimmed off the bits of molten plastic, so I'm at a loss as to why it had stopped running, despite the fact that there is clearly some heat damage evident. Go figure? I can only think I disturbed something, maybe a bit of grit, jamming it somehow, perhaps down the side of one of the bushes, that has now come free, and in its absence, the motor now runs freely?
07-18-2022, 11:20 AM
