Backup generator install question

I’m having a problem getting a backup generator for a house running. The unit is installed and has been checked over by an electrician and when he was out told me to have someone adjust the gas pressure regulator down to 6″. So I had someone adjust the gas pressure and the thing still won’t fire up. I was told by one tech that the maxitrol regulator installed are notorious for causing problems with generators and I should put an actaris regulator in instead. Does any one have any advice on how I can get this thing fired up? Thanks