Miller Aead rpm

[Mchevelle]

I have a miller aead. I set the weld rpm to 3000. When i start to weld with the rpm drops down to about 2000 to 2400. Any ideas about what the issue could be?

[duaneb55]

Are both cylinders of the Onan firing?

[Mchevelle]

Yes both cylinders are firing. They both have good compression and spark. It produces power fine and has strong weld output initially until rpms drop. Maybe a fuel issue?

[snoeproe]

Have you attempted any basic troubleshooting?
is there a fuel filter in the fuel system?
is the fuel tank cap venting properly as it should?

[Mchevelle]

Yes it has a fuel filter. I changed it first. The fuel cap is venting properly. I'm wondering could the fuel pump be delivering enough fuel to let it run at high rpm but not under a load?

[Mchevelle]

Or possibly a governor issue. Does the governor adjust to keep the motor at 3000 when its inder a load?

[duaneb55]

As Mchevelle suggested - perhaps a governor issue.

I've seen weak speed springs allow for excessive governor droop or perhaps the spring is anchored in the wrong governor lever hole affecting its sensitivity. Moving the spring anchor point closer to the governor operating shaft will make it more responsive. Too close and the engine will surge.