Chrysler Repair: 2.5L V-6 wont start...no codes, crankshaft sensor, upper radiator hose

Question
My 95 chrysler sebring lxi wont start sometimes it would start if i spray starter fluid but now it does not.

i replaced the crankshaft sensor and it started right away with no problems for a few months i checked the egr valve and its fine.

The fule pump makes the rrr nose so i know it is not that.
Also the only code i get is 12 then the 5 pause 5 and then nothing else.
(ps) sometimes when it does start i drive for a while and then when i park it wont start again

Answer
Hi Paul,
No start with no meaningful codes is a challenge. (12 and 55 are not remarkable). I wonder if you are getting spark, so check that with a spare plug in one of the spark caps and with its threaded shell touching the cylinder head while a helper cranks the engine. If the spark is o.k. then fuel and mixture need to be considered.
I would remove a spark plug and verify that it is wet with unburned fuel after cranking it unsuccessfully for a few seconds. That would show the pump is pressurizing the injectors and they are injecting. Then you might want to check the compression of one cylinder to assure timing belt and timing are ok. After that it gets down to whether the coolant temp sensor is off-value so as to not produce a good mixture but not so bad as to set a fault code. Measure the resistance across the two terminals of the sensor (located adjacent to the thermostat housing which is attached to the upper radiator hose). See if the resistance is between 9,000 and 11,000 ohms at 77F, and even higher if the temp is colder than that. If it is not that high then you are getting too lean a mixture. Another possibility is the MAP sensor is off-value but not enough to set a code. You could probe the dark green/red wire with a fine pin and measure the voltage to ground when you simply turn the key to run, and then when you crank it to see if the voltage drops from 4.7 or so, down to below 4.0 when cranking.
Those are my suggestions, as well as to keep looking for fault code. I assume that your gas gauge is accurate, so consider whether that might be the issue.
Please let me know if you find out what is wrong or get a hint as to what it might be that we can pursue.
Roland