starting problems
 

I have a 1989 190E. The engine will crank, but will not turn over and start . Ocassionally in the mornings when still cool outside it will start, and drive great, but later in day will not. Had battery replaced, alt. checked, and sparkplugs replaced. No change. Any ideas?

If the engine cranks/turns over but will not start, the first thing I would check is the fuse on top of the OVP relay that is behind the plastic cover behind the battery.

starting problems
 

We replaced the fuse, but did not change anything. It still just keeps turning, but won't kick over and start. Anything else I can try?

Do you have the 2.3 or 2.6?

Intermittent starting problems can be very difficult to diagnose. It helps to know if it is fuel related or spark related. There are several things that can cause hard or no start. Before throwing money at new parts, go over all of the vacuum hose connections, especially on the Idle Control Valve. Check both ends of these hoses for tight connections and any cracks or visible problems. These hoses become hard/brittle over time.

Has your distributor cap, rotor, and spark plug wires been replaced with correct type along with non-resistor spark plugs? Below is a Rotor that got a guy to work in the morning but the engine died when he was driving home.

http://i179.photobucket.com/albums/w...rokenrotor.jpg

When the car fails to start, do you hear the fuel pump/pumps operating? If not, you might have a defective Fuel Pump Relay. Bad solder joints can cause problems.

http://i179.photobucket.com/albums/w...lpumprelay.jpg

http://i179.photobucket.com/albums/w...pumprelayB.jpg

http://i179.photobucket.com/albums/w...pumprelayD.jpg

OK, so you replaced the OVP Relay fuse, maybe the relay itself is bad. You can check a few components with a VOM to verify if it is good.

http://i179.photobucket.com/albums/w.../OVPRelayA.jpg

http://i179.photobucket.com/albums/w...d/OVPRelay.jpg

http://i179.photobucket.com/albums/w...gSchematic.jpg

Another item that could cause your starting problem is a defective CPS,Crankshaft Position Sensor. It goes from the flywheel to the Ignition Control Module. It can cause intermittent starting problems, engine dying, etc.

http://i179.photobucket.com/albums/w...Sensor300E.jpg