Gas Fireplace won't produce flames for long

[MarshMarlowe]

My Fireplace is a natural gas log insert, Direct Vent style
Manufacturer: FMI Products LLC
Model: (V)VC36N

Here's the issue I'm having -
I can light the pilot, and the pilot will stay lit indefinitely, and produces what appears to be a strong pilot flame
When I flip the switch on the wall to ignite the fireplace, it lights and the flames will get high as per normal. But this is temporary. Slowly but surely, the flames die down, and I hear a "click", and the fire and pilot light extinguishes. I can re light the pilot and try again, but I always get the same above results

In my own research, I found that a faulty thermocouple is usually the cause. I tested the thermocouple with a multimeter and found an erratic resistance that measures anywhere from 16 millivolts to 3 millivolts, but the majority of the readings I saw were closer to 3 millivolts. I understand that less than 7 millivolts indicates a faulty thermocouple.

I decided to order a whole new pilot assembly, that consists of a pilot hood, a thermocouple, and a thermopile. Part number 0199702

I have other gas appliances in my home (gas water heater / gas range) and I have no issues with using those appliances, so this seems to indicate that I do not have a gas flow issue

My question is - given the symptoms I described, would a new pilot burner likely fix my issue?

Thanks

[MarshMarlowe]

Update

I replaced the Pilot assembly and I'm still having the same issue

[hearthman]

This is not a DIY site so we can't provide details how to troubleshoot. We do recommend you get a pro in there to troubleshoot it. It could be many things ranging from venting to gas supply to the components of that fireplace, etc. Throwing parts at it is no way to go about it.

[MarshMarlowe]

Thanks for the input. My next step will be to hire a professional for further diagnosis. So it's known, the part I replaced was diagnosed as faulty via a multi-meter reading that seemed to indicate as such. I replaced the whole pilot assembly including the thermocouple because it basically required the same effort as replacing the thermocouple, contained other parts known to fail over time along with the thermocouple, and wasn't much more $$$ than the individual part. The advice I initially received to replace this part came from a licensed gas plumber, so this wasn't exactly "throwing parts" at a problem.

[parry73]

I had this same problem with my fireplace after using it for 1 year. The fix was simple maintenance listed in the manual. Turn off the gas, including the pilot light. Using light air pressure(under 30psi) blow air through the air feed holes in the main line and the pilot assembly. I do this a couple times a year and have had zero problems.

[MarshMarlowe]

I had this same problem with my fireplace after using it for 1 year. The fix was simple maintenance listed in the manual. Turn off the gas, including the pilot light. Using light air pressure(under 30psi) blow air through the air feed holes in the main line and the pilot assembly. I do this a couple times a year and have had zero problems.

I tried that as well, no luck

As it turned out, the vent hood was never properly installed. It came loose and fell down in such a way that it was partially clogging the vent tube, which starved the firebox of oxygen. I fixed it and all is well now

The vent hood issue was listed in the troubleshooting section as a possible cause for the fire going out during use.