Fuel Tank Out and Being Cleaned

We have recently uninstalled our fuel tank to clean it. After taking it out, we realized there was still a great amount of old gasoline inside. We also tested our fuel pump and realized it is broken, so we ordered a new one. When we poured out the gasoline, we realized it was very red and had an unusual stench to it. Overall, we think both our fuel pump and the old gas in the tank would be a problem with the lack of combustion in the engine. We are currently cleaning it and going to let it dry then reinstall it. In the meantime, we will most likely be putting in new spark plugs. Here are some photos: