Chevrolet Repair: 1998 S10, 2.2L, Evap System I/M Monitor wont run, fuel level gauge, gm service manual

Question
Recently this truck up and quit running one day. This was caused by a faulty wiring harness connector on the crank position sensor. I repaired this with a new connector from GM.During the repair I disconnected the battery which caused all of the I/M monitors to clear.

After completion of the repair I ran 2 drive cycles, per the GM service manual, in preperation for emission testing. All I/M monitors indicated a has run status except the evap monitor. No DTC's are set.

After reading the service manual I discovered that the fuel level signal was required for the system to operate properly. Something about the fuel level signal being needed by the PCM to calculate expected tank vapor pressure if I understand it correctly.

Up to this point the fuel level gauge had been bouncing between full and empty with the low level light coming on. I replaced the fuel pump/fuel level sending unit with a new Carter assembly and wiring harness pigtail. This corrected the bouncing gauge problem.

Still after 2 more drive cycles the evap I/M monitor will not run and no DTC's have been set.

More reading of the service manual seems to indicate an evap system cleaning may be required along with possibly some component changes, specifically the canister purge valve and vapor canister.

Could these components be defective causing the problem without setting a DTC or may there be something that I am overlooking.

Answer
Hey,

 What kind of scan tool are you using?  I have noticed that when I use the Genysis or the MT2500 the evap cycle suspends and won't run. But when it is all disconnected it will run after a drive cycle or two. The Tech2 has a evap test in the special functions menu.  Did you try to run the test through the tool?  I think the lastest OTC update for the Genysis runs this test but I don't even bother with it because the TECH2 is so damn reliable. I assume the vehicle is going in to loop right?  I did get caught on that before because of a faulty thermostat and only realized it because it eventually set a code related to engine temperature time.

Wayne