We have some old ones that have a seperate fuel lock & convertor , which has worked well in the past .The new ones are a convertor and lock all in one . so if you have a prob. with one you have to tend to them both at one time , but less probs. all together.Over a period of time you may have to richrn the mixture up on cold days to start the engine, cause lp doesnt have a choke .,& yes the LP that I have workrd on from day to day does create moer carbon than a gas engine ./ They tell me that Lp is sopposed to burn cleaner than gas ( I don't beleive that ). I have had to take an intake off and take a torch 7 burn the carbon out of one . The engine couln't breath. The engine was only 3 years old. Lp does have it;s advantages though you just have to stay on top of it over time. 9 just like anything else though) tonight so bare with the misspellin