Ok welding gurus, got a problem:
I was welding on my bumper this afternoon and lost all Ar/CO2 feed to my gun on my Snap On 120V MIG. My canister was just filled-- reads 1200 w/ regulator set at 20 cfm.
Here's what happened: I was welding just fine; put the gun down; picked it up and began a new weld and pfffttttt! no gas-- porous very distinctive no-shield welds. Any idea of what might have happened?
I popped the top of the welder (top load spool) and looked at the gas lines that I could see. The hose feeding the gun seemed to be okay so I assume the gun and hose are okay. My gut feeling is that somewhere the delivery is fawked between the hose inlet from the tank and the hose outlet to the gun. Sound about right? I didn't hear any gas leaking anywhere around the welder so I think maybe there is just some blockage somewhere.
Can someone describe how a welder allows gas to flow to the gun? Is there a one-way valve somewhere that may have clogged? Is there a solenoid that opens and closes to allow gas flow when the trigger on the gun is depressed? I just want to know what to look for when I break down the welder tomorrow.

Thanks

There is a solenoid that makes that happen.

I figured as much. Is there an easy way of determining whether or not the solenoid has burned out or gone bad? I don't want to start taking the internals apart and break something REALLY badly. Any other suggestions as to what may be wrong?

before ya start taking solenoids apart, pull off the cone at the end of the gun, most likely a piece of spatter has clogged a gas orifice or two, clean it up real pretty like, and give it a shot. Keep it simple stupid:flipoff2: if that aint it, then try the trouble shooting chapter of the manual.

I already cleaned the nozzle thoroughly and cleaned the tip well. Unfortunately I bought the MIG used and the manual was not included.

If you check the regulator there might be some thing blocking the gas flow.A couple of times I have had crap block the oriffice in the regulator,but in my case I could still hear the gas solinoid engage.Good luck