As long as we're stopped for the night....
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buy one of those red plastic gas cans... but that company was put out of business by class action lawyers
?? Red plastic cans are available everywhere here. But...
Back 20 years I was refilling the Simplicity in a snow storm (it had a plow). I slipped, and sloshed gasoline all down my overalls. A splash on the hand is no big deal. Overalls soaked from crotch to toes BURNS.
That was about when B&S introduced their safety can. I got one. It shut-off when fuel reached the tip. Very reliably: I could walk away until the gurgle stopped. But I couldn't put it on the moving van, left it behind. Now I can only find two types: one with a manual shutoff (and too-flexxy nozzle), and one with "auto shutoff" which works poorly when new and soon sticks in the "always off" position. I have to yank out the gizmo and tape up the catch-notches to make it an arsonist's can (stays open all the time).
Neither is really right for a mower tank because there is only a hole in the top. I'd have to pump or siphon fuel over the rim before it would flow down to the carb. Also want to seal around the fuel line yet also have a large hole for re-filling.
That Bug-Stop comes in a one-use sprayer. But unlike Hudson and clones, which have a pickup tube to the top, the Bug-Stop wand hose comes off the bottom! I knew this would be handy for something, so when empty I busted the seals and washed it out. For this job I tossed the air-pump and stuck a plastic disk in the top cap (w/ small air-hole).
Real problem is that with low-mounted factory tank, the battery and solenoid go where gravity fuel wants to be. I rigged 3 boards to bridge across the dash and firewall to support the Bug-Stop tank.
There's a shutoff now. Although the needle is new, you have a point about not trusting it.
Also a large garage in the next town burned (and delayed my garage project because they hired my contractor to re-build). The story was a tractor "backfire". But as you say, a leaky needle may have been involved.
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find a proper gas tank...
Back 15 years I replaced the Simplicity with the cheapest in-stock Murray. It came with a small gravity fuel tank between engine and driver. There was lots of room and extra holes. I discovered that there was another tank, over twice as large, in other Murrays. I bought one and it fit like it was meant to go there. (Actually I had to cut-away part of a sticker: you could squint fuel level through the side with the hood closed, the squint-slot in the cowl was for the tall tank, but my model's sticker covered all the height the short tank lacked.) If I were to put money into a 1974, that's probably what I would get.
-or- There's LOTS of boats here. There are standard extra-fuel tanks for outboard motors. They lay flat, and have a hand-pump. I have to look closer at one, but I suspect one way or another they could be adapted to the mower. There's even a standard quick-fitting so you can disconnect without losing fuel and carry the tank to get more fuel (or set it on ground for easier filling).
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The electric pump I bought burned-up in less than 5 gallons. It looks like a transformer that has been shafted by a hex fitting:
It goes tunk-tunk-tunk several times a second, different when passing air or fuel or stalled on a full carb. Now after a few minutes it stops tunking, and if I leave it powered it gets HOT. So hot it has blackened the coil. Obviously there is an iron slug inside the hex, and a coil to hump it. It looks so low-tech that I ass-umed it had some mechanical switch to break the coil and let the slug rebound. Nope. It is an NE555 and a 50V 8A HEXFET! One solder joint is dubious but that is to the coil and if it lost contact the coil would be cold not hot. Somehow it is stalling with the coil on 100%, toasted the tape around the coil and darkened the enamel on the coil winding. I suppose I should take the PCB out, load it, run it on 'scope and meter, on the stove to make it hot, and see what's failing. It is remotely possible the tractor dynamo runs over the 15V(?) rating of a '555. But the battery more often seems under-charged than over-charged. (Especially since the throttle slips and RPM is often well below 3500 rated.)
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pick up a Chinese riding mower
Are they Chinese? I think the majority of production of non-fancy brands has concentrated in MTD (Murray gave it up a few years back). And they got there with US production efficiency. Overseas shipping would add cost comparable to Chinese labor/steel cost savings. Engine production has also shrunk; Tecumseh quit a few years back. So that leaves B&S (which still boasts "made in USA", though their small kart engine looks like a classic Honda cement mixer mill), and Honda (who does a lot of casting and bolting in the USA), and Robbins(Subaru).