I'm back. Thanks for the responses from the first post.
I was out welding and came across the sputtering problem. I've got good gas flow (I took the nozzle off and can feel the gas coming out, can hear it when it's back togethter). Tightened all wire (cable) connections. Came across one piece of metal that the arc would sputter on. I ground the ground contact surface area clean. same problem. ground clean the welding surface area. same problem. Tried a different piece of metal (didn't clean anything), welded fine. Tried the problem piece- sputtering problems. Went back and fore between the pieces a couple times- same situation. Tried cleaning the problem piece more- same problem.
The metal is mild steel. This piece I am having trouble with is one that I cut off an 8 ft. piece. The other pieces from the 8ft. piece weld up fine. I had a couple of other pieces that I had trouble with that came off other 8 ft. pieces. I've been using the same materials for the last couple months and never had this porblem until the last two days. I adjusted the gas to 20. The cylinder is about 1/8 full. does the pressure go down when the cylinder gets less full?
Oops, I didn't see your first post. I thought you were welding with scrap pieces. :-)
It sounds like you've checked all the mechanical connections.
When it starts to sputter can you hear the contactor relay and gas solinoid valve clicking on and off? This would indicate a problem in the trigger switch or leads back to the machine. (sometimes binding the gun in weird positions is how you find a break in the trigger lead) ;-)
If the sputtering is not caused by the contactor cycling then I would guess that something is breaking down internally. You will have to take it to a repair station that has a Load Bank to properly test it.
Intermittent problems like this can really be a pain. Sometimes it's better if the magic smoke comes out of the machine all at once. (especially if it's under warranty)
p.s. You did check that the contact tip was the right size? Too big can cause sputtering.
Thanks for all the advise.
I went out this evening and did alittle more checking and noticed that the wire was not feeding very smooth or as fast as it should. Cleaned the drive rollers, readjusted the tension and it seems to cure the problem. I'm guessing that the one piece I was having trouble with was probably more to do with the way the cable and gun was positioned (more friction for the wire) than the metal piece itself. Live and learn.
Thanks again everyone!
Keep in mind that the conduit liners ARE consumables. They have to be changed occasionally when they get clogged with dirt/grime. I've also seen where someone has dropped something (steel or cylinders) on their gun lead and crimped the liner. I usually test my liner everytime I change the roll of wire by pulling the leftover wire through the gun (after removing the contact tip). After a few times you will learn how much drag it should have. Make sure there isn't a kink or burr on the wire where it comes off the spool.
Thanks to all that gave advise. I would think that the liner should not be worn yet. I've only gone through the small roll of wire the welder came with and a small amount of the second roll. I will clean and check the liner on the next roll.