I only paid for a used Coleman Maxa 5000 gas generator with a 10HP Tecumseh engine. we totalled a outlay at no bucket as well as it was 140V. we plugged in my shopvac that brought a engine speed down to 120V. Turned off a shopvac as well as a outlay went behind up to 140V. we am disturbed about deleterious overvoltage as well as swell when we essentially need to make use of a generator. Is this a approach it’s ostensible to be? If not, how can we "slow" a engine down? Thanks for any help.