atomic_fungus (atomic_fungus) wrote,


So, hied myself to the garage and finished with the battery charger. Found that in 12v mode it manages 11.3v, and that's coming straight from the transformer. Replacing the transformer is beyond the scope of this project, but that's okay because in 6v mode it does provide enough voltage to charge 6v batteries...and guess what the dirt bike's electrical system runs at? (Battery charger does 7.6v in 6v mode, which is fine.)

That completed, I put it away, then turned my attention to other things. Had a gander at the MGB fuel pump sitting on my workbench and decided I'd see if it could be repaired. That took me another forty-five minutes, but after tracing the circuit I found that continuity was lost at the points. All it needed was to have the points cleaned up; I took them out and sanded them clean with 800 grit. That done, I reassembled it and adjusted it from a procedure I last read in 2004, and it works a treat now. Hook it up to 12V and it happily churns away, pocketa pocketa pocketa like in "Secret Life of Walter Mitty". (The story, not the idiotic movie.)

It's a diaphragm-type fuel pump. When energized, the solenoid pulls back on the rod, which displaces the diaphragm, drawing fuel into the pump. At a certain point the points throw over, breaking the connection, which allows the spring to push the diaphragm out, pushing fuel out of the pump. (There's a couple of disk valves to keep the fuel going the right way.) It's actually really simple, and the main point of failure is the points which--as I demonstrated tonight--is a pretty simple fix if you know what you're doing. This is a fuel pump which was replaced in late 1987 because it had stopped working, and it's been knocking around the garage for THIRTY YEARS.

Well--I still want to convert my parts washer over to something that will use an actual solvent, instead of window cleaner. This fuel pump will, strangely enough, suffice as a solvent pump. I just need to figure out what to use for a tank for the solvent, and plumb a drain into the washer tank, and do a few other things. The funny thing is, I have an older 5 gallon Jerry can which would make a spectacular solvent tank; I'd just need to attach a fitting for the fuel pump intake and another one for the outlet from the washer tank. How I'd do that depends on what kind of suction this pump has. As I recall, in the MGB, the fuel tank outlet sits only a little lower than the fuel pump inlet, so I'm not sure how far this pump can lift. I would not expect it to be very far. The output can easily push fuel high enough to force it through the washer nozzle, and fast enough to make a healthy stream--I know that from that time in 1990 the car died at the gas station and I pulled the hose off the carb to make sure I was getting gas--so I'm not worried about that.

I do miss that MGB, I'll say that, but it was long past time to let it go.

It appeals to me to make my parts washer's solvent conversion kit out of as much found material as possible. Using this fuel pump would be a major step forward.

Incidentally--this is the kind of technical acumen a certain test excluded. Heh.

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