Stick with the basics, and look for simple problems first. Make sure you have a fully charged battery, and that it's cranking the engine over fast. I think you have a kill switch at your remote control (plastic clip on a lanyard). Make sure it's in place. The spring controlled button has to be held out/open by the clip. (If SURE you have spark, it's not the switch.) Screw out one or two of the plugs and check to see if they are wet. If blackened, clean them up with some carb cleaner.
For starting, it's the manual primer bulb that feeds fuel to the carbs, not the fuel pump. Not sure if you pulled the carbs off to correct the starting problem, but should hear fuel flow into the carbs when you pump the bulb -- which should be fairly hard when the carbs are primed.
The spark and compression testers tell you condition -- easy DIY tests. A $10 adjustable spark tester, for example, will tell you if you have spark, and then how strong it is -- i.e., whether it's strong enough to fire the engine.
