My lincoln wire feed welder while welding,the weld stops and starts without letting off the triger.The wire feeds just fine. It seems the power output stops and starts real fast. Can you help with this problem. Oh ya I have never changed the tip.

I would say there is no electrical contact on that setting. Check this first. Good Luck Friend.

Check to see if the wire feed pressure is set correctly. Sounds like it's a little loose.

Been welding for a while, open side, check for proper tension on the feed wheel inside side panel, hit the trigger, if feed motor continues to spin tensioner needs tightened or mig wire may be getting hung up inside main cable lead. If motor is off on off on then its probbably the switch on the trigger getting a bad good connection, hope this helps o and check welding tip on gun end, may need replaced if worn or melted, unscrews.

check for circuit breaker by drive motor, it may be the pc board.

Your Linner of the gun could have a kink in it.

Have you checked the tension on the wire roll feeder? Inside the unit where the spool is, the wire feeds off of the spool, through the feed roller, this roller has a tensioner spring on it that keeps the wire flowing steady, and also check the spring tension the keeps the spool from turning freely, keep this loose as can be, and just enoughthat it doesn't unwind on it's own.
There are so many things that it can be, but this is a start.
Good Luck.
Paul

These welders have thermal breakers in them so if they get to hott the will automatically stop feeding the wire but the fan will remain on, try changing the breaker i think its in the door where the spool is held. good luck]

1/4" plate with a 135 amp machine is probably beyond it's duty cycle abilites. If you are using a mixed gas, and pushing the max on the settings, it will be cutting out because it is designed to.
You might want to get a higher amperage welder for consistent welding of 1/4"
The 140 Pro maxes out at 5/16" using inner shield wire. and 1/8", or 10 guage with gas.

open the area were the role of wire is and check when trigger pulled if any action to feed motor. [wire might be stuck at end, or there usually is a small fuse in that area for feed motor]

a mig welder must have a good ground to work, also dont try using rusty wire it will jam in the liner, have you checked you are getting wire feed from the neck? just pull the tright and with the welder on it should feed out, if you can stop it its to loos tighten up the pinch roller, is there power on this wire feed? i have often seen new welders strick up the weld with to slow a wire feed and to many amps running, what happens then is it burns the wire away in one flash, right up inside the welding tip and every thing comes to a grinding holt then???? it can and often will just weld the wire into the tip,, witch may mean a new tip is needed, take off the shroud and try to unscrewing the tip if no wire comes out when you pull the triger
as the wire is stuck or welded to it you may be able to get it out still??? but its best to fit a new one in, go one size bigger than the wire your using at first as you are sure to get it very hot??? untill you get the hang of welding,,, use a good gas mix like argon light it will weld stanless steel as well?? but co2 works well on miled steel only, the problem with co2 is its a cold gas and you need a lot more amps to weld the same thickness of steel use it at about 2 to 4 psi only indoors, out doors use it at 4 - 6 psi and if out doors keep out of the wind as much as you can or it will only blow the gas away from your weld if that happens you cant weld without gas being there as a sheeld, dont try using a no gas welder they are like the devel having a bad hair day to use,
even a good welder wont like one? there c*ap!!!!
only try welding clean steel not rusty steel or it will spit like mad at you and you wont get a good weld,
if at all,,one of the most common fults that is
but i bet you have weded the wire to your tip?
its so easy to do at first,,only two word of warning
keep well raped up, sparks well fly and were gloves',,,
and keep your head sheeld on well over your eyes dont ever ever look at the welder when welding it will burn your eyes realy bad and you will wake up in the night feling like some git has just pored sand into your eyes and its going to hert like hell for day's,,,
i find the solor head sheel is far better, its nearly clear when not welding and go's dark in milliseconds you will like them as you can see what you are doing right up till you strick up the ark then it go's dark,,
most welders last for years iv had mine for the last 35 years it a clark 150 turbo mig, and iv doged it to death too,,,
the only thing that could realy go wrong inside them is the rectifier, mains coil or a relay,, not much left in it to go wrong ,
and now iv bored to death good luck with your welding ,,i hope this has helped you out