turn your ignition key several times to build fuel pressure, remove air filter slacken off fuel line to injector and push air flow plate down this will raise the plunger in the metering head and will replicate the effect of air been sucked through. You should then feel the resistance on the plate from the fuel pressure as your pushing it down. This type of sytem is totaly dependant on fuel pressure, you can have good fuel pressure but it may not be enough to open injectors as they only open by fuel pressure there not electronic like most modern systems. They need a fair amount to open. Best to get pressure checked by a good quality gauge