Engine Trouble - intermittently won't start! Any ideas on what to look for?

[Snowbelt Spyder]

All fuel injected engines can become flooded. It just doesn’t happen that often. That’s why the ECM is programmed with an “engine clear mode”. BRP/BOSCH calls it “drowned engine mode”, or something like that. The 998 was especially sensitive to that for some reason. Probably why you heard it trying to start. It might start after sitting all night. If not, go through all of your start steps, hold the throttle wide open first, then hit the start button for about 10 seconds. Fuel is cutoff when doing this allowing the engine to clear. Then release the throttle grip back to the normal position and try the start again. Repeat once more if necessary. Let the starter cool a bit before more repeated attempts. Many 998 owners have needed to do this at some point. About once a year for my old 2012, especially after a stall or aborted start.

 

[Roadsterryder]

How about the Crank Position Sensor failing intermittently?

How would I know? She started up fine today and I drove another 25 miles with 2 stops and every time she started up again…

All fuel injected engines can become flooded. It just doesn’t happen that often. That’s why the ECM is programmed with an “engine clear mode”. BRP/BOSCH calls it “drowned engine mode”, or something like that. The 998 was especially sensitive to that for some reason. Probably why you heard it trying to start. It might start after sitting all night. If not, go through all of your start steps, hold the throttle wide open first, then hit the start button for about 10 seconds. Fuel is cutoff when doing this allowing the engine to clear. Then release the throttle grip back to the normal position and try the start again. Repeat once more if necessary. Let the starter cool a bit before more repeated attempts. Many 998 owners have needed to do this at some point. About once a year for my old 2012, especially after a stall or aborted start.

She started up this morning without any hesitation. Drove 25 miles with 2 stops. First stop after 1 mile to top of the tank and added some more Heet Injector cleaner and water remover. She started right up and I continued my trip to Home Depot. When I tried to start the engine again about 15 minutes later she did not start right away. It‘s like she tried to start but died again. Turned off the ignition right away, waited about a half of a minute, tried again, and she started right up…

 

[mecsw500]

If the engine cranks and whilst it is cranking you should see the rev counter respond. If the rev counter doesn't move then there is a possible crank sensor problem. They are notoriously finicky sensors that often get killed by heat and then become intermittent depending upon heat cycles and drive you to the point of distraction.

You can buy an aftermarket one for well under $40 off of Amazon. You don't have to tear the engine apart to get to it and change it.

If it happens more often after the engine is hot, that's when crank position sensors love to die. I've had them fail on many cars and motorcycles and spent hours chasing my tail on other miscellaneous causes. I hate them with a passion, whether they are optical or hall effect technology. They often fail to trigger error codes which makes me dislike the things further.

They should also not be short circuit or open circuit measured across their terminals when unplugged from the harness, using a ohm meter setting on your multimeter. Different types have different resistance but most should not be open or closed circuit. I'd start with cleaning up the harness connections with contact cleaner.

Frankly, after all the fuss you have had, you might want to just change it with a cheap aftermarket one. From what I was able to look up the BRP part number is 420966570 and fits a variety of BRP vehicles but you might want to check that. They are on Amazon and fit like 200 different Can Am vehicles. If it isn't the problem then you can always return it.

I found them on Amazon for pretty cheap. You might want the OEM part from BRP if it fixes the issue for long term piece of mind, but I suspect the $120 BRP part is a $30 cheapo part anyways.

 

[Snowbelt Spyder]

How would I know? She started up fine today and I drove another 25 miles with 2 stops and every time she started up again…



She started up this morning without any hesitation. Drove 25 miles with 2 stops. First stop after 1 mile to top of the tank and added some more Heet Injector cleaner and water remover. She started right up and I continued my trip to Home Depot. When I tried to start the engine again about 15 minutes later she did not start right away. It‘s like she tried to start but died again. Turned off the ignition right away, waited about a half of a minute, tried again, and she started right up…

Yeah, it's frustrating. But history has shown that every 998, unless it was a garage queen, transitions through the same series of issues that need corrected at some point. That's why EVERYBODY with any experience knew that your MAP sensor vacuum hoses would be cracked. They all did it. That's why I pointed out to you the WOT engine clearing steps above. Also, if you haven't already down so, I strongly urge you to do a canisterectomy ASAP. Use the forum search function for instructions. I wouldn't get too concerned about this or that hypothetical failure, until you've proactively taken care of the things that you know will be an issue down the road. The better news is that you have a SM5 and don't have to worry abut your shift linkage falling off. Keep at it. Good Luck.