I have a 97 Formula 111 600. When the engine is cold the idle is at 1500rpm. When it heats up the idle drops off and sometimes stalls the machine. Checked the plugs and they are a little on the dark side as opposed to tan. I am using NGK BR9se. Any info appreciated.

Cheers
Bryan

Have you tried adjusting the idle speed?

Have you tried adjusting the idle speed?[/b]
yes

Did you try opening the pilot air screw?

It seems to idle low when it is warmer out. -10 to -20 it idles fine.

B

Does your sled have DPM? I wonder if the temperature sensor in the airbox is bad. My 2000 manual says:

When checking the enrichment solenoid, disconnect engine temperature sensor connector. The DPM system now operates as though the engine temperature was - 20°C (- 4°F) to allow maximum mixture enrichment

So, when the engine is actually cold, it will idle fine. When the engine is warm or the air is warm, and you have a bad temperature sensor, the DPM will still think the engine is cold and continues to supply a mixture too rich for the warm engine. And if you supply too much fuel to a warm engine at idle, doesn't the engine speed fall off due to the overly rich condition (ever apply the choke on your lawnmower when the engine is warm and running)? And your plugs would then be a little black?

I might be wrong, but I suspect (if you have DPM) that your problem may be in the DPM air temp sensor. If you don't have DPM, then I'm just another idiot!

Steve

oh yeah, the manual also provides the data to check the sensor:

Temperature Sensor (air and engine)
At room temperature 20°C (68°F), the sensor resistance
must be 2500 W ± 300.

I suspect that is 2500 ohms +/- 300... my pdf version may not have the right Greek letter.

That makes sense. If I do have DPM where might I locate it?
I'm also just another idiot.

cheers
Bryan

DPM has some extra vacuum tubes coming from the carbs to a small "manifold" on the side of the airbox. The sled will have a "computer" module as well. I've attached a picture from a two-cylinder Summit. They did have DPM in 1997 on the three cylinder sleds as well.

Steve

is your clutch set right? could be trying to drive the belt.

Thanks for the info. I don't have DPM on this sled, but I went back over the idle screws and one had somehow turned out. Got it working fine now.

cheers
B