My Polaris Magnum 330 has been getting more difficult to start (it used to start with some cranking) and now it won't start at all. No popping whatsoever, not even with starting fluid.

Here is what I checked:

- fuel - I tried adding gas into the spark plug hole; I also tried starting fluid; after some cranking i can smell (and see) the gas in the carb with the air filter removed. I think I am getting fuel.

- air - removed the air cleaner. when I crank I don't feel like there is suction. if I crank with WOT, there is good suction.

- spark - removed spark plug, touch engine block, crank - good nice blue spark.

- compression - using a compression gauge, start to crank, 60 psi. with WOT jumps to 120psi. stop cranking, start cranking again, it goes to 40 psi, for some reason, not back up to 60. (dunno why that is ?)

- took off the flywheel cover to inspect the flywheel / key. The slots seem to be aligned.

Was going to go look at the valve clelarance next.
I already have the front covers off, just probably need to remove the fuel tank.
What else should I look at?

 

Yes I'd go ahead and check valve clearance,.006 intake and exhaust. 60-90 psi compression on average(some may go higher) because of the decompression device on the cam.If the gauge drops could be the valve core leaking. Try a different gauge to be sure. I'd install a new spark plug anyway.Check that you have fuel going to the carb by pulling the fuel line and cranking the engine over.This can eliminate the fuel pump.IT should at least try to kick off with starting fluid if compression is ok(timing ok as you say) and have good spark. If it tries to run with starting fluid,the problem may be carb related,stopped up jets,etc. Go through the trouble shooting guide to see if you missed anything.

Engine Turns Over But Fails to Start
No fuel
Dirt in fuel line or filter
Fuel will not pass through fuel valve
Fuel pump inoperative/restricted
Tank vent plugged
Carb starter circuit
Engine flooded
Low compression (high cylinder
leakage)
No spark (Spark plug fouled)

 

Thanks OPT you're the best.

I will 1) check the valve clearance and 2) check fuel pump and report back.

One question -- is the visual inspection of the flywheel and key, with the nut and washer off, sufficient? Or should I pull the flywheel to be sure?

 

If the woodruff key is in the slot along with the slot of the flywheel lined up,timing should be ok. Main ones I've found that would shear keys were the 500 engines. Here's a flywheel and key that was posted here a couple years ago that took a beating and split. If the slot in the flywheel is wallowed out too far,it would either have to be replaced or try to have a machine shop repair it.

 

Well Im gonna take a pic of my flywheel and post it... My slots line up but the key seems to be further in there than in your pic.

Something came up and I had to leave the farm early, so, won't get back to it for at least a week

 

Got a couple more hours to work on my quad today, here's the status:

Spark plug: I replaced it just in case. Tried cranking, also tried starting fluid. Does not even "cough" but I did get one big backfire (with flames).

Fuel pump: removed the "fuel out" line. Fuel just drips, regardless of whether I crank the engine or not. There's a test in the service manual, with a vacuum pump, I'll try that later today.

Removed the carburetor while I am in there because why not, might as well.

Tried holding my hand near exhaust, and when I crank, it alternates between blowing air out and sucking it in. That surprised me, I didn't think it should suck the air in.

Did not get to the valve clearance because had to remove the tank first anyway, and then I realized that I needed a functional hand pull starter (and mine tore off recently) so have to order that first.

 

As long as you're sure the fuel valve is letting fuel get to the pump inlet nipple,the fuel pump sound like it's trashed out. New ones are cheap on ebay and amazon. By all means clean the carb and install a good Shindy kit.https://www.ebay.com/itm/Shindy-Carb...haAzO9&vxp=mtr Valves set at .006 intake and exhaust.

 

Ok, went to adjust the valves, they were both very tight, a lot less than 0.006. When I was done I tried it and then realized I had no spark.

Right before this all started happening, the recoil rope broke.

You guys know where this is going. Yep the rope crap must have increased the pulse coil gap.

I'm gonna pull the flywheel, inspect the pulse coil and fix the gap. It does not look like I can get to it with the flywheel in place...

 

Yes,know where this is going..Rope breaking will do it every time seems like.Had this mainly happen on the 500s but can happen on any model with a recoil. Hopefully you should be able to gently tap the bracket(if it's bent) toward the flywheel without removing it. .016-.030 air gap between the pick up coil face and flywheel interrupter strip. Hope it's nothing more serious.

 

Well the screws that hold the pickup coil in place are behind the flywheel, so... took the flywheel off (using the proper tools), took off the pickup coil. There is some small damage there -- the plastic body was pried away from the metal bracket that would normally be bolted in place. Everything else seemed undamaged.

I am going to try to glue the bracket to where it should be, then set everything up and then measure the air gap... will report my results... thanks!!!