99 F1 50 won't start

Dirty battery cable terminals, faulty cables or loose earth connection, engine wont turn water in cylinders, battery goes open circuit under load. can cause this fault.

Hey Todd how's it going ? How's the battery ? battery connections ? Are there any lights lit on the dash , security , check engine ? Because your getting a clicking there is nothing wrong with the theft deterrent relay ! Take a volt meter on the 20 volt scale an put negative lead at the negative battery post , then take your positive lead an put it on s terminal small wire on the starter solenoid an have someone turn the key to start position , you should see battery voltage . If you see battery voltage there is nothing wrong with the theft deterrent relay ! or the crank circuit. You need to do a voltage drop test on the starting system ! I'm thinking possible battery cable ! Starter Voltage Drop . you do know that you replaced a starter for no good reason !

What happens when you turn the key to on? Do the warning lights and gauges come on? Turning the key to start, do the lights and gauges stay on? Just nothing at the starter?

Or does power just shut off when you turn the key to start, everything goes out, no warning lights or gauges? Then check cables, battery terminals, grounds for clean tight connections. There is a problem between the battery and the ignition switch.

If the switch still receives and sends power out (to the dash, for one) but start circuit is not working (from battery to ignition switch to clutch switch to starter relay to starter solenoid to starter to ground-and back to battery), then here's where we at: with key off, use a small screwdriver and short the big cable at starter to the starter solenoid small wire connection, or use a small jumper wire to do the same-battery cable at starter to the small wire connection on the starter solenoid. Starter motor should spin and crank engine. Does it? If so, start checking the start wire out of ignition switch for power when key is held in start. If you have a clutch switch, check for power in with key in start. Should have battery voltage to the clutch switch with key held in start. Keep checking the start wire along the start circuit. Not sure how the start relay is wired into the circuit, would have to see a diagram, but if you pull the relay out and use a test light or multi meter, could check for power on the terminals where relay plugs in. Key off, should have one terminal that is hot. With key held in start, at least one other terminal should also be hot. This would be the start wire out of ignition switch sending a signal to the relay.
Good luck, hope you find it. Sorry I don't have a wiring diagram to help you more.

Pull and clean all terminals on starter.

CHECK BATTERY VOLTAGE IT SHOULD BE 12.5 VOLTS.IF NOT BATTERY WEAK NEED CHARGING OR REPLACED.IF BATTERY GOOD.TURN IGNITION SWITCH TO ON POSITION WITH ENGINE OFF.DASH LIGHTS SHOULD LIGHT UP IF NOT.CHECK IGNITION SWITCH FUSE.IF FUSE GOOD YOU HAVE A BAD IGNITION SWITCH.IF SWITCH IS GOOD.I AM LOOKING IN FAULT IN STARTER SOLENOID OR STARTER.OR BATTERY CABLES NEED REPLACING.WARNING TURN OFF RADIO BEFORE DISCONNECTING NEGATIVE BATTERY CABLE SO YOU WONT LOSE RADIO PLAYING CODE.

battery is dead again let it charge longer then try it.
clean your cables and then have the alt and battery checked if they are both good then something is staying on like mine my brake lights stayed on once and killed the battery
good luck

Try having someone turn the key to the start position while at the same time someone else taps on the starter with a hammer. If starter begins to crank the engine or makes weird noises or begins to smoke then you need a starter. If nothing happens, then using a test light or a volt meter check for power at the "S" terminal of the starter solinoid when the key is turned to the start position. The "S" terminal is the small terminal to the right of the terminal where the battery cable goes when viewed with the battery cable terminal at the 12 Oclock position. (usually a purple wire). Hope this helps.

Have your Starter Solinoid Checked. Sounds a lot like the Culprit!