What is this? And do I need it?

[1-8-4-3-6-5-7-2]

There are some gauges that tend to read low. If you haven't already done it, verify the temp with something besides the dash gauge. If there was no thermostat, the temperature would likely be even lower.

Sorry, forgot to mention I was going by the reading on my Scangauge II. I use the dash gauge as a general reference only, but don't count on it for accuracy.

 

[Supercharged111]

A malfunctioning charcoal canister can cause a raw gas stink, but only if the plumbing isn't intact. It's not one of those things that robs your motor of power, I'm personally a fan of charcoal canisters.

 

[JayMB]

That thing on the side of the cannister with the cut wires is the vent solenoid. Not all trucks had them. My '99 3/4 ton Vortec 350 does not have one. The vent solenoid is used to close off the vent during a test of the emissions system that some trucks of this era do periodically. My '99 has a vent opening that is permanently open, and does not have the ability to leak test it's charcoal canister because of this. I that the OP is correct in assuming that someone grabbed that one off of another truck at a junkyard and put it in to replace the original which was damaged in a collision. I would either leave it alone, or if you have a fuel smell problem - you could either remove the solenoid from that charcoal cannister so that it's "permanently vented" or go find the correct one in a junkyard (maybe 3/4 ton trucks would be a good starting point) which doesn't have that solenoid with a plug on the side. Removing the cannister will make fuel smell worse and will not help power, reliability or fuel economy at all, so I would personally keep one on the truck.

 

[Graffhopper]

No, no check engine light. I asked in another thread about the check engine light but nobody answered, so I'll ask here again... the check engine light never comes on. When I turn the key on I though the light should come on to show it's working then go off once the engine starts, but the light never comes on. I pulled the cluster thinking maybe someone pulled the bulb, but it was there. I swapped it with another bulb to confirm it was a good bulb, and both bulbs are good. I scanned it and the only code I get is an occasional O2 sensor heater circuit code.

If you want check engine to come on try disconnecting and unplugging the EGR.