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I have a little Uno inherited from my dad. Just before he passed away he was having trouble getting it to start, and before that, having it die on a drive somewhere, even close.
I would now like to solve the non-starting problem first. The battery is charged and seems strong. It takes many tries to start and revs of the starter motor before it shows much discharge. I will be working along, and therefore have difficulty with things like turning the starter and checking for spark. I will rig a jumper lead from the battery to the starter solenoid for this.
I see the possible causes of non-starting as:
Electrical - no spark voltage from the coil. - no voltage to individual plugs from the distributer, very likely points. - no power at all for the ignition system. No idea where to look here. Fuel - No fuel. The car does have fuel though, ruling that out. - No fuel reaching the fuel pump, i.e. a blocked line or filter. - No fuel reaching the carb, i.e. a malfunctioning fuel pump. Carb - A blocked jet or cannel somewhere. - A stuck float or malfunctioning float valve (dunno what it's really called). - A stuck butterfly, allowing no air and ergo no vapourization of fuel.
I'm asking this question not to directly ask what is wrong, or what must I do, but I would like to narrow things down, and am hoping that members here familiar with the Uno could give me a start, say a prioritization of the possible faults I list, and, or, additional faults I could check.
Start with sparks. If you don't have a good spark, then you don't have anything that'll get it going!
Whip out the plugs and have a good look at 'em - I don't know what the plug gap should be, but they do wear out (they generate sparks, so they erode away as the sparks are created as the gap gets bigger - bigger gap, worse spark, and also can be later spark). Then all you have to do is wedge one of them onto the engine block and turn the engine over with your bypass wire - you are looking for a good fat blue spark. Yellow is a bad sign.
Good spark at each plug means (probably) that the whole electrical system is working (though the advance / retard could be stuck, it's generally a vacuum system running off the inlet manifold and it normally affects running rather than starting because when it fails it's generally because the hose has split).
Then it's fuel, and that's a lot harder to work out: Try cleaning a plug as best you can, then putting the plugs back in, and try to start the engine for a minute or so. Quickly remove the clean plug and smell it - any petrol? Does it look wet? What colour is it? Brown or tab is good, black or white is bad.
If you can isolate it to one system or the other, it makes a huge difference!
Those who fail to learn history are doomed to repeat it. --- George Santayana (December 16, 1863 – September 26, 1952)
Those who fail to clear history are doomed to explain it. --- OriginalGriff (February 24, 1959 – ∞)
THis is a bit trickky, you need to pull the carb apart.
That is something close to the top of my mechanic skills list. I stripped and cleaned the Weber on my Renault 5 almost every week because something was wrong. I couldn't fix it, but strip and assemble it I could almost do blindfold.