Once again I need help from this great site. I have a problem thats driving me nuts. My 89 300E is currently having an intermitant problem starting when hot. IE: stop by 7 eleven for a short stop. It will turn over but not start. If I remove the green wire with red stripe from the coolant sensor it normally starts right up. I've changed the OVP which fixed several other problems but not this one. I've also change the O2 Sensor. I changed the coolant sensor a couple of months ago trying to fix a cold start problem. Not sure maybe I got a bad Coolant sensor? The crazy thing is u never know when its not going to start, doesn't do it all the time. When the vehicle is cold, no problem. SHould I try a new coolant sensor or does my problem lay else where. Any help would be greatly appreciated.

You may want to check the sensor when it is acting up. Put one of the wires from the VOM to ground and the other to one of the 2 posts on the coolant sensor. Take the reading on both posts. They should be very close to one and other. If not, it is faulty. You may try to swap them over. (One goes to the EZL, ignition, and the other goes to the ECM for the fuel)

VOM = Volt Ohm Meter.