My rider is Yard Machine by MTD Model 678 (More specific - 13af678g205)
The mower will start as long as I either pour a little gas into the carb or shoot some starting fluid into it. Once started I can drive it around all I want until I engage the blades. It putters and within five seconds it dies. I found out that if I engage the blades and then shoot some starting fluid into the carb it will run for about forty five seconds. If I repeat this process it stays running.
Other symptoms include dying when I try to lower the throttle and occasionally dying when I have it running in high speeds for a long distance. Also when I engage the blades I hear high pitched belt sounds and smell hot rubber. I do not know if the belt can contribute to this or not.

Clean the carbs high and low speed jets need to be checked out probably gummed up or trash also replace fuel filter.

I hate to sound like an idiot but it turned out that all that was the matter was a fuse. I figured since it puttered then it had to be a fuel problem but the guy told me that the fuse controlled the carb

Carb is dirty, or the fuel is contaminated.

Fuel contamination won't effect it

I literally watched a new fuse go into the mower and every problem I listed was cured

Hey MM:

What about a faulty fuel cut solenoid and a bad fuse. The fuel cut solenoid might not have been doing it's job, but when held open (replaced fuse) the mower acted normally. Speculation on my part.