Help - Fan on all the time ?

[Guest Lshorter]

I have an Nc750x , went for a ride today came back gave it a wash , started it up and the fan was on immediately, engine management  light on and water temp light on. When I turn it off and restart the bike struggles to start but all the lights go off but runs rough? Any ideas ? 

[Guest Jonnyboy]

Is there any coolant in it?

[Guest Lshorter]

Yes there is 

 

[Guest Jonnyboy]

Did you wash the bike with a pressure washer?

[gonzo 2,211]

Water in the electrics,!! I dont use pressure washers,.

[Guest Lshorter]

No just a sponge and bucket 

[Spindizzy 7,109]

Not sure where the NC picks up the coolant temp. If you can find the sensor that does that, its likely shorting somehow or going to ground as wet which would make the bike think its too hot. So you would get fan,overtemp and engine light. Might also overly lean the fuel if it thinks the engine is really hot. Would also make it hard to start.

 

I am no expert on the NC internal workings but have experienced the above on other bikes. Find that sensor and dry it out!

[embee 7,288]

On the NC700 (I'm assuming the 750 also) the fan is controlled by the engine ECU, using the coolant temperature sensor which is in the thermostat housing, right side of the cylinder head top, forward of your right knee as on the bike. There isn't a temperature "switch" as often found on other bikes, usually in the radiator header tank. The ECU decides when the fan is required and sends a signal to the fan relay, which powers up the fan.

 

I'd start at the coolant temperature sensor in the thermostat housing, remove the connector, dry/lube (WD40 or contact cleaner etc).

 

It won't lean the mixture, it should be running on closed loop/stoichiometric if warm unless there is a fault and it has defaulted to a limp mode. If the EGO/lambda sensor connection is bad it might cause problems and would certainly flag a fault, so check that also. Trace the wires up from the lamda sensor fitted in the right side of the exhaust just as it leaves the cylinder head, a disc looking object with wires attached.

 

A few reports have been made of faulty HT leads/plug caps. Unplug them from the spark plugs, spray with a suitable water dispersant (WD40 or similar), dry off and refit. Possibly dry them with warm air if possible, hair dryer etc.

Edited March 4, 2017 by embee