[Lvoyles]

I have a 2016 CForce 500 HO that will sometimes start and run (does have a rougher idle than when originally purchased). Majority of the time the machine will start and idle for less than 10 seconds before shutting off. After that it will crank but not turn over. Getting fuel and spark. Took it to a dealership and got it back with a unable to reproduce the problem. Have rode it maybe 3 times in the past 6 months due to this issue

[doug80638]

Are you mechanically knowledgeable? How many miles on the machine?

There are so many potential causes. Bad sensor data, valves out of adjustment, low fuel pressure, bad fuel, low voltage, bad/high resistance connections/grounds, etc. Where you start can depend on your mechanical abilities.

I usually start with a PDA to read what the ECU is seeing, but most folks don't have one of these but there are posts in this forum that give instructions for making one. This is one of the first things I thinks owners should do as they are invaluable for chasing difficult issues.

Then I check the mechanicals (compression test, fuel pressure test, voltage draw tests).

At this point, either something has jumped out as a problem, or a bunch of stuff has been eliminated as a cause, and you move on from there.

An alternative is to take video of the problem when it happens and bring it back to the dealer to show them, but labors rates are expensive if they have to walk the diagnostic tree.

Good luck.

[Lvoyles]

It's got 150 miles on it. The exhaust smells rich when you try to turn it over after it dies. I have drained the fuel tank and replaced the fuel. There are unfortunately no codes stored either. I unfortunately don't have a lot of diagnostic tools at my disposal.

[NMKawierider]

I think I would be tempted to test the engine speed sensor...aka CPS and IAC valve. Both have been a problem for CFMs. While I was at it I would also pull and clean the air temp sensor/Mass airflow sensor. Coated with oil from the air filter they give false readings to the ECM making it lean it so far it can die when cold. Clean it only with mass airflow sensor cleaner..nothing else. Otherwise it will be damaged.

[Lvoyles]

See where I'm perplexed is the problem occurs more when the machine gets hot e.g. a warmer day or the engine is hot. I have better luck starting it when it's cold.

[NMKawierider]

See where I'm perplexed is the problem occurs more when the machine gets hot e.g. a warmer day or the engine is hot. I have better luck starting it when it's cold.

When mine gets coated it dies when I put it in reverse and touch the gas..and that's after it gets warmed-up. Clean it and that BS stops for some reason...and now that I stuff a paper towel inside the Uni after servicing it and give it a quick squeeze to suck-up the extra, it almost never happens anymore.But when it does, I know what to do. 

[doug80638]

150 miles! Damn! It hasn't even reached it's first service interval yet! Are you the first owner?

Original paper or aftermarket oil foam air filter? Have you checked it recently? (any critter activity?)

I'm trying to think of issues that can occur from sitting idle for long periods of time, and fuel is on the top of my list.

How old was the gas in that thing before you flushed it? Will it fire or start if you use starter fluid?

Was the dealer able to reproduce the rough idle? Did they hook it up to a PDA and check all the sensor values (hot and cold)?

Has the valve lash ever been checked?

[Lvoyles]

Doug I am second owner. Original owner is my father in law. I had it fully serviced just to make sure that wasn't the issue. Original air filter was in great conditionas of monday. I used before the issue started about 2 to 3 times a week. I checked trail cameras and put feeders out for deer. But I didn't do alot of shutting it off and turning back on. Generally it was left running the entire time. I was putting fuel in it about once a month using the recommended octane or as close as I could buy. I also took it to the gas station so I wouldn't have gas jugs full of old fuel.

[doug80638]

OK. So it always starts and runs fine when started cold and not shut off. But once hot and turned off, it may not restart until it cools off. Is that accurate? 

The original paper filter eliminates an oil fouled T-MAP sensor as a cause, but I'm still suspicious of a sensor issue; engine temp, O2, stuff like that which could tell the ECU to start with too lean a mixture (which is why the starter fluid test was mentioned). Voltage issues seem improbable as well unless there is a loose connection impacted by the heat (check the battery leads for tightness, but don't over tighten).

I don't know what "fully serviced" included, so I'm still inclined to recommend checking the valve lash.

Clark,

Were there any Evap issues with the 2016's?

[Lvoyles]

I guess the better way of stating it starts better in the cold is that it starts more often in the cold as compared to when the ambient temperature is warmer. If it does start no matter the temperatureit seems to have a rough idle which the dealership didn't notice. Fully serviced to me was check and replace all fluids and filters. So every filter and fluid has been replaced.

[NMKawierider]

Clark,
Were there any Evap issues with the 2016's?

No Evap systems on anything in the US prior to 2018.. I believe. (Fully serviced just means properly cleaned and oiled)

[doug80638]

OK. Engine cold. Rough starts in all temps, but worse in warm temps or warm engine. Always rough idle. No diagnostic tools. Got it.

Engines start better when cold because more fuel is delivered by the ECU until the engine warms up which is why it smells "rich" when it dies after a few seconds.

Check that the spark wire lead is securely connected to the spark plug.
Clean the T-map sensor as Clark suggests, using the proper chemical spray, just in case.

After that, I would check the valve lash. It's usually checked at 200 miles so it needs to be done anyway. Lots of machines have had hard starting issues that were related to valve lash.

A compression test while the plug is out for the lash adjustment is a good data point if you have the tool. You can check the plug at the same time. Some machines have had issues with factory plugs as well, and while there usually are no visible signs of a failure, replacing the plug has fixed the issue for some.

After all that, you will have either identified the problem or eliminated several possibilities, without spending a lot of money.