Engine not starting at all

If your 2008 Polaris Trail Boss is not starting from the ignition switch but starts when you jump the solenoid, there are a few possible causes for this issue. Here are some troubleshooting steps you can follow:
1. Check the ignition switch: Even though you mentioned that you installed a new key switch, it's still worth verifying that the ignition switch is functioning correctly. Make sure it is properly connected and that the contacts inside the switch are not worn out or damaged.
2. Inspect the wiring: Examine the wiring harness connected to the ignition switch, solenoid, and starter. Look for any loose, corroded, or damaged wires that could be causing a poor connection or preventing the signal from reaching the solenoid when you turn the key to the "crank" position. Repair or replace any faulty wiring as necessary.
3. Test the solenoid: Even though you mentioned that the machine starts when you jump the solenoid, it's still worth testing the solenoid itself. Using a multimeter, check if the solenoid is receiving power when the key is turned to the "crank" position. If there is no power, the issue could be with the ignition switch, wiring, or a related component.
4. Verify the starter: Ensure that the starter motor is in good working condition. If the solenoid is receiving power, but the starter motor does not engage when you turn the key to the "crank" position, the starter motor itself may be faulty and need to be replaced.
5. Check the battery: A weak or discharged battery can also cause starting issues. Make sure the battery is fully charged and in good condition. Clean the battery terminals and ensure they are securely connected.
If you've followed these steps and are still experiencing difficulties, it may be helpful to consult a professional mechanic or a Polaris dealer who can diagnose and resolve the specific issue with your ATV.

Video below might help

Eliminate the battery as the issue first up.
Check if you can jump start the car from another vehicle with its engine running or at least have the starter motor kick over the engine. If it starts then you know your battery is the issue. Having lights does not mean the battery has enough cold cranking amps to turn over the starter motor.

2. If the starter cranks the engine over as normal with a jump start from another car but your engine does not start you have also eliminated the starter motor as the issue.

3. If it does not start and the starter motor will not crank the engine over either when you jump start from another vehicle, then there may well be a problem with the starter solenoid, the starter motor itself or with the wiring to the starter solenoid or to the starter motor. No power getting to the starter motor solenoid or to the starter motor and obviously the starter motor will not turn over.

4. So I need not write much more here, there is a very good guide to solving starting issues here which I suggest you might like to read.

No Start Problems

you mean it wont crank, it must crank to start.
1: bad starter system
2: weak battery even a new battery can be weak.
if you dont charge it first.
or if it starts ok then wont later, that means cars charge system failure.

can you jump start engine? with jumper cables.
that be a big clue there, proving starter works but battery was weak.
if the battery is fully charged.
you can hot wire the starter solenoid, (tiny terminal)
if car cranks now, the key start wire is failing.
A/T or M/T tranny? both use different path here....??????

if you cant hot wire it, then that means the stater is bad
the cables bad or the battery is not really connected.
or possible the engine is seized, can you hand turn over the engine at the front crank bolt (CW , facing rear, in neutral)
if not motor is seized.
some times even the starter and rig gear can be seized.
the starter can be bench tested. too.
http://www.fixkick.com/nocrank.html

ill answer for NO ELECTRICAL POWER :
sure and is easy with any DMM meter, got one? any $20 DMM.
my guess;1
engine will not crank
dash lamps out.
head lights out. dead.
post systems of electrical system , all parts that work and those that dont work, and problem is easy.
cleaned battery terminals.
tried borrowed battery that reads, 12.6vdc ? (charged is 12.6)
2012 that is in warranty car.... ?
my guess on 2012
jumping a car, that is battery jump starting.
a battery can short, and no jump start on earth will start shorted battery in car. but does lay down some big sparks, or burns up cheap walmart cables.
if the car will not crank, say just that, my starter motor will not crank
jump started from live running other car.
if true then make sure headlights work , if they dont work fix that first.
HL must always work, even keys in pocket.
best is to put a fully charged battery in the car, jump starting can cause
surges that can damage sensitive electronic$$$, do jumps as a desperate measure,
with a charged battery,
1: Head lights work, no fix that , use voltmeter
2: cranks robustly.
no , wiggle shifter lever, (on A/T cars the park switch blocks cranking) On M/T the clutch blocks cranking.
with any dMM
measure battery voltage before crank and during.
12.6v good. reseted.
cranking.
0 to 10v bad (weak battery or shorted starter motor)
11 and above good. and must crank, if not , starter is bad.
to prove starter is bad, check voltage at starter solenoid coil wire lug.
it must be at 11v cranking , below 8v it chatters, and fails.
if at 0v cranking this lug that means the Key start line is failing.
A/T switch not closes, or bad ignition switch.

either you have a very bad battery, or your not guetting fuel for it to start.

What happenes when you try to jump start the vehicle? If it starts - then it is most likely the battery or alternator. If it doesn't start then the solenoid or the starter or the engine. To get it down to the starter or engine - disconnect the serpentine belt and turn the crankshaft with a wrench. If it turns - then it is your starter/solenoid.

The starting system consists of:

• starter motor
• starter switch, part of the ignition switch
• starter motor solenoid relay switch
• starter solenoid
• starter drive

When you turn your key to start your engine, it just clicks, right? If so, more than likely this is due to a bad battery. Even though your battery may appear to be fully charged, it may have a dead cell, or worse. If you get a jump, does the vehicle start? If so, replace your battery.

Possible sources of the problem if the engine does not crank or the relay clicks:

1. Battery
2. Starter motor
3. Starter motor relay
4. Ignition switch
5. Damaged fuse
6. Anti-theft system
7. Circuitry

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

well now,,, 200 amps,, sounds like a realy big kick dont it? trust me,,,thats nothing more that a cheep torch battery,,,you will need at least 400 cranking amps just to make that starter grunt over,, fuw things to look for,,, 1,,is the engine sezed,,,2 is the starter motor a good one? as it sounds like it has a short in its feild windings 3 or warn out brushes 4,,or burnt out solenoid cap,, 5,,or even a realy bad engine earth, 6,,,bad battery clamps 7 even dry bushes in the starter,,,, to be honest,,,i would wip off the starter first and strip it down or fit a different one on just to try it out,, i bet its the satrter letting you down though

you mention it almost started which suggest the motor turned over... if it did that it's not seized. i would hook the jumpers on for about 15 minutes before you even attempt to start the car. if the starter still won't work... hit it with a hammer as you attempt to start it... if it starts up you likely need a new starter.

Robert

try over riding the starter relay on the fender ,it has one there right?. dont go to a mechanic yet. the engine aint seized. if it doesnt have this relay then i would get the alternator tested. if you want to test it yourself it can be costly for the right equip. autozone usually tests for free. i dont know were you live so if theres not an autozone. let me know if you cant get it tested.