'Small Engine Repair' is going to lose a lot of audience member's attention in the first 60-70 minutes. That's how long it takes for anything of interest to happen in the film. That shows a lot of trust in its audience to hang in there. The absolute key if you are going to structure your film that way is that the pay-off has to be worth it. Sadly this film can't live up to that requirement.
When I read that this was based on a play, that made a lot sense. A very dialogue heavy script with contained settings. Even the strongest plays can struggle to make the transition to film. They just feel so pointlessly limited. It's really noticeable here.
I don't want to savage this film because it doesn't deserve that. It is a bit of a frustrating ride though. The ending is fun and helps to save it a bit but by then the damage is already done. Not one I'd recommend. 5/10.