I discovered my jeep wouldn't start the other day... the battery was dead. When I tried to jump it, it wouldn't even turn over - but I heard a lot of clicking and there was some smoking near the starter solenoid on the inside fender, passenger side. On closer inspection, I found some rubber was burning - presumably a short was heating up a wire up.
Checking the wiring diagram, I found that the previous owner had removed the fuse links that go from the battery to the alternator, manifold heater, ignition switch, and a few other things. I couldn't tell what was shorting so I inserted some 10 amp fuses where the fuse links would go. One of the fuse links went to the alternator... is 10 amps enough here??
This time, the jump almost worked. She turned over and over for a while (phew, a big worry gone - the starter motor was fine). Finally, she caught and started firing, but only for a half asecond. As soon as the ignition kicked in.
I discovered my jeep wouldn't start the other day... the battery was dead. When I tried to jump it, it wouldn't even turn over - but I heard a lot of clicking and there was some smoking near the starter solenoid on the inside fender, passenger side. On closer inspection, I found some rubber was burning - presumably a short was heating up a wire up.
Checking the wiring diagram, I found that the previous owner had removed the fuse links that go from the battery to the alternator, manifold heater, ignition switch, and a few other things. I couldn't tell what was shorting so I inserted two 10 amp fuses where the fuse links would go. One of the fuse links went to the alternator... is 10 amps enough here??
This time, the jump almost worked. She turned over and over for a while (phew, a big worry was gone - the starter motor was fine). Finally, she caught and started firing, but only for a half a second. As soon as the ignition kicked in, she basically died. What a bummer :( I found both fuses blown. So my question is... is 10 amps enough here for both fuses? If so, what should I be suspicious of as causing my problems? If it's not, how big should each fuse be? One goes to the alternator, one goes to the ignition switch and manifold heater.
That's why these circuits use fusible links instead of a fuse. A fuse and fuse holder would be too expensive, multiplied by thousands of units sold per year. You could replace the fusible link with a circuit breaker, since you will only be buying one of them.
You can purchase fuse link wire by the foot at lots of auto stores or at the $tealership. You need close to the same length as was in there and you need to crimp connect the wire in because solder will damage it. It will be a 14 ga. fuse link wire protecting those circuits. Each one is about 8" long.
The smoke was likely from a bad connection at the solenoid. Same for it dying as soon as you stopped cranking it. New solenoids are less than ten bucks.
I would replace the solenoid, clean up the connections, add the proper chunks of wire and then see what happens. You would need something big, like 60 or 100 A to replace the fuse links, but I 'don't' know the blow out rating for the wire other than a dead short.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Probably not a "short", unless you meant the common sense of "something's not right with the electrical system". My guess is that the smoke was the result of rust. Rusty connections have high resistance, resistance under surprisingly small load produces heat (think light bulb filament here), heat produces smoke.
Apart from the battery cable and starter cable attached to the starter relay (that black can bolted to the inner right fender) there's only two wires that run to the relay: One runs to the key switch and sends B(+) voltage to the relay when you turn the key switch to "Start". The ground return path is through the mounting bolts to the fender and back to the battery, so you need good clean connections here.
The other wire runs to the B(+) side of the coil, IIRC. It feeds full battery power to the coil (as an aid to starting) so long as the key switch is in the "Start" position. Once the key switch is released to the "Run" position the relay drops out and voltage to the coil drops to something around 7 volts via a length of resistor wire loomed into the OEM harness, or a GM-style resistor block in replacement harnesses.
Are you certain that the battery is dead? This could just be rusty battery connections at the battery or the relay.
Are you certain? Fusable link looks very much like ordinary primary wire but the jacket generally isn't bound to the wire strands inside. Beware too that you didn't shorten the resistor to the coil (inside the loom, probably in the part that runs across the top of the firewall), full battery voltage will burn the coil up.
Failed Ford starters don't generally click, they usually don't do /anything/ when they fail. Or, if the Bendix drive fails (had one once) they spin up and whine, but nothing else.
I'll bet that it was "as soon as I released the key" and the relay stopped sending full voltage to the coil. With the engine not running and the key switch in the "run" position check the voltage from the coil B(+) terminal to a good ground, you should get something lower than 12 volts.
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