The Amperage draw is so high it locks the starter solenoid. This can be because of a bad starter bushing, low voltage in the battery, timing, etc. It is a major engineering defect in the design. All Fords prior to 1992 have this flaw. It can result in a fire, dead battery, etc.
The good news is Ford redesigned their starters in 1992. The new starters
will fit the old engines and Ford sells a retrofit kit to rewire the Solenoid for the new starter. The way it corrects the problem is the old solenoid becomes a starter relay, with the output wire now going to a solenoid mounted on the new starter. (This gives you less of a voltage drop at the new solenoid vs the old solenoid, that solves the problem in most cases)
You need to buy the kit from Ford (Under $20.00) but you can buy the starter anywhere. Just give them your vehicle information as if you owned a 1993 Ford when buying the starter. You can also get a rebuilt starter from Ford. You could make your own kit, but the Ford Kit is everything you need and comes with instructions (priceless).
Warprunner
it's easy to check the solenoid, put a screw driver across the large nut & the smaller one, and if the starter engages it's the solenoid .make sure the vehicle is in park, or the e- brake is on. ( with key on)
Probably a bad starter solenoid.
You should locate and test the solenoid. Most have three connections. There is a large cable from the battery to the solenoid, from the solenoid to the starter and from the start switch to the solenoid. The power terminals to the battery and the starter are large and have large cables. The starter switch connection is much smaller. Turning the key to 'start' provides a low current voltage to the solenoid causing the solenoid relay to close and power from the battery cable to connect through to the starter. If that voltage is present then the solenoid or the wiring between the solenoid and battery or solenoid and starter is suspect. If that voltage is missing then the starter switch or solenoid feed line may have failed.
Not to bash on the last answer, but, the starter solenoid probably isn't at fault here. If it will start with the screwdriver then the starter solenoid is functioning. It either does or it doesnt. The answer lies in circuitry back from the solenoid to the ignition switch. You could have a bad ignition switch or neutral/safety switch.AnswerDefective starter solenoid.
If the key is on and the shift is in park you can safely start the unit by engaging the solenoid with a short jumper wire.
What do you mean it will start up half way? If the car will start then it can't possibly be a problem with your solenoid. If the solenoid is bad then the car would not start at all. If you hear just a clicking noise then that means your solenoid is fine but that the starter itself is malfunctioning or that there is not ample power to turn the starter over once the solenoid has engaged. One other problem could be high resistance in the wire that connects direct battery power over to the starter.
Good power all the way to the starter, 12 volts at solenoid/start circuit wire when key engaged, but no click or starter engage
The starter relay or solenoid is probably the problem.
There is an electrical problem between the starter switch and the starter solenoid. The most likely cause is a loose connection at the solenoid or the fusable link has melted.
Starter solenoid sticking. Replace the solenoid if it is external. If it is internal, then just replace thee starter. It will cost a little more but you will have a new starter and solenoid.
If the starter is whining while the engine is running at an idle you have a problem with the ignition switch or the starter solenoid is stuck. The starter should not be engaged while the engine is running unless you are holding the key over on the start position.
The problem is almost definitely your neutral safety switch. When you jump the solenoid you are bypassing it. The problem is your starter is going and needs replacement
It can be a defective starter assembly that causes this problem. There are two parts to a starter assembly: the starter motor and the starter solenoid. The offending culprit is usually the starter solenoid, and it should be replaced.
it's easy to check the solenoid, put a screw driver across the large nut & the smaller one, and if the starter engages it's the solenoid .make sure the vehicle is in park, or the e- brake is on. ( with key on)
Then the problem could be either the solenoid or the starter. Most likely it is the starter.
the solenoid is broken. sometimes if you strike the starter motor sharply this cures the problem.
Usually you can bang on the starter with a hammer when it doesnt want to start and that will do the trick. It will engage and the car will start. If that is the case then the problem is the starter itself and not the solenoid. You can also remove both and take it into any Kragens or autozone and they will bench test it for free and tell you. You can also use the screw drive method by bypassing the solenoid and applying power directly to the started by laying it across the 2 terminals. if it starts then the solenoid is the problem assuming you have power to it.