I just bought a new house and a new smoker. There not working together properly

My outdoor plugs appear to be on the garage circuit, which is protected by a GFI. Most of the other plugs near windows where I can get power out of the house are on the kitchen GFI circuit. Every time I plug in my Big Chief smoker to smoke some fish it pops the GFI. At one point I actually took all of the other load off the circuit and plugged the smoker in all by itself. It still popped the GFI. Any idea why this is happening? Are there any workarounds where that allow me to keep the GFI plug in the circuit? Currently the only things I can think of are
1. Remove the GFI plug from the garage circuit, but then I have outdoor plugs without protection.
2. Run an extension cord through the darn house from a non GFI protected circuit( I have a 2 year old, this idea won't work very well)
- The smoker is a 450 watt appliance
Jeff