Miller bobcat 225 with Onan p226 welding issues.

[Hpwinc2004]

So I bought a miller 225 with an onan p216 engine. It sat up for a while the guy said but when looked at it ran fine for the few min he showed me. It's my first gas generator / welder. Not that I have cleaned the tank really well, replaced the fuel pump, new filters (oil and gas) new oil, new spark plugs. Removed and cleaned carb. It will run fine when first cranked and then after about 5-8 min it wants to bog down. It's likes it's in a bind and the throttle will go to wide open and shut off. I can play with the idle control pin and slowly let it catch back up and it will go to running fine again. Stike a weld and it will cut back out again. I've read a lot of forums already and just still scratching my head.
Serial number: KD467987 any advise would be helpful.

[H80N]

Hopefully CRUIZER will check in..... yours may be one of the ones that need a vent hole drilled in the gas cap....

[Hpwinc2004]

I've ran it with cap off and on took the fuel pick up out cleaned it and even ran it on a different tank just to be sure. Like I said head scratcher. Yeah he seems to be the miller genius after looking at all the forums he seems to diagnose them all...

[H80N]

ONAN manuals PDF

http://www.wheelhorseforum.com/files...m-492-4006pdf/

http://www.mytractorforum.com/images/reference/Onan_16_18_20_24.pdf

[duaneb55]

Sounds as if the pulse fuel pump isn't keeping up with demand.