I HAVE A 1999 WHEELHORSE 312 IT WILL NOT START WITHOUT JUMPERING THE STARTING SOLENOID I HAVE REPLACED THE STARTER SWITCH AND SOLENOID AND CHECKED THE RELAYS AND SAFETY SWITCHES

Can you jumper the solenoid on the starter and make it crank ?
Do you have power to the relay when the key is in the start position ?
Power goes from the key switch thru a crank fuse, then thru the neutral safety switch, then to the starter relay. The relay sends power from a 40amp ignition fuse to the starter solenoid.

If you are sure that all connections are clean and bright, including the battery to the ground and battery cable to the solenoid, jumper from the battery (+) to the solenoid (+). If the solenoid clicks, but motor doesn't turn over, your solenoid is bad. Try jumpering momentarily from the battery (+) to the starter (+) and that should cause the starter to rotate. If that makes your starter rotate, your solenoid is still bad. Be sure that your starter has a good ground connection

Might be bad starter relay, or bad ignition switch. Check for voltage to starter when key in start position, or turn on headlamps and try to start. If lamps dim, bad battery connections, bad ground, bad replaced starer. If lamps do not dim, starter position on switch may be bad. You could try using jumper from battery to start post on solenoid to see if it cranks. If it does, you have either a bad ignition switch, start relay, or wiring problem.

Yes, the solenoid is mounted on the starter.
One small jumper wire from the battery cable connection on the starter to the small wire solenoid connector should cause the starter motor to work and crank the engine. If key is on, engine should start. A small screwdriver works too, besides a jumper wire.
Check for voltage on the small wire to the solenoid with the key held in crank: if voltage there, the problem is the solenoid or starter motor. If no voltage to the solenoid, power has been lost between the ignition switch and the solenoid-possibly the neutral safety switch.

AS YOU HAVE CHANGED ALL OF THESE COMPONENTS TO NO AVAIL IT HAS TO BE A BREAK IN THE WIREING ITSELF, YOU WILL HAVE TO FOLLOW THE WIREING WITH A MULTI METER TO FIND WHERE THE POWER IS LOST.

does it spin real fast without clanging and grinding against the flywheel? if so then its probably the solenoid bad. do you have to hit the starter with a hammer then it works? it is probably bad brushes or a worn motor. eather way i think you can only get a new starter and solenoid together not sold seperate. check for bad battery cables (loose).

Check your starter solenoid, its located on the fenderwell, easy way to do it is put ignition switch in start position use a jumper wire and connect the two large terminals, if it starts quickly remove the jumper, then replace the starter solenoid, if nothing happens replace the ignition module.

Hi government32, seeing how you just installed a new battery I'll assume you cleaned all the connections. Not cranking at all sounds like 3 possibilities, Key switch, starter solenoid, or starter. Lets check starter first. Using a jumper cable, jump from positive battery post to starter motor (you'll see the connection on the motor where cable is connected,thats where you hook jumper), if it cranks the starter motor is ok. If it doesn't thats the problem. If it does crank check the starter solenoid, using a jumper cable jump across from side to side (the 2 big terminals). If it cranks now the solenoid is bad or the electrical connections are dirty. There are also 1 or 2 small connections on solenoid from the key switch, make sure they are clean. If these 2 components check out the key switch is bad or the connections on it are dirty. (its usually not the switch).Hope this helps you.

well you can short over the starter and see if it starts. honestly i would remove the starter and take it to your local autozone. they will check it for free. also check the start solenoid. they have a tendency to cause the same effect.

this is caused by burnt starter solenoid contacts, U can either replace the starter solenoid contacts (about $15) or u can replace the entire starter.