'90 Cherokee starting problem

[Guest]

On some mornings, the engine cranks like normal but does not start. If I use starter fluid in the throttle body it will eventually start and re-start throughout the day. I had the crank sensor replaced six months ago after having the same problem. Could that sensor go bad again? The problem comes and goes, always originating in the morning. I would appreciate any suggestions.

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.

[Guest]

next time it wont start try unplugging the tdc aka cps sensor if it starts up thats the problem and need to replace it... if that doesnt fix it then try pulling of the throttle body and cleaning it real good make sure and take off all the sensors first but be careful your throttle position sensor has to be adj with a volt meter when you put it back i dont have to do this they did away with that in 91....also try replacing your idle air control motor....
themud

	Crank position sensor A crank sensor is a component used in an internal combustion engine to monitor the position or rotational speed of the crankshaft. This information is used by engine management systems to control ignition system timing and other engine parameters. Before electronic crank sensors were available, the distributor would have to be manually adjusted to a timing mark on the engine.

	Throttle position sensor A throttle position sensor (TPS) is a sensor used to monitor the position of the throttle in an internal combustion engine. The sensor is usually located on the butterfly spindle so that it can directly monitor the position of the butterfly throttle valve. The sensor is usually a potentiometer and therefore provides a variable resistance dependent upon the position of the butterfly valve (and hence throttle position). The sensor signal is used by the Engine Control Unit (ECU) as an input to its control system. The ignition timing and fuel injection timing (and potentially other parameters) are altered depending upon the position of the throttle, and also depending on the rate of change of that position. For example, in fuel injected engines, in order to avoid stalling, extra fuel may be injected if the throttle is opened rapidly (mimicking the accelerator pump of carburetor systems).