From Old Man Wags

There are several factors that limit your draw strength on a standard down stream injector.

1. Every accessory after the injector limits draw. If your in a pinch and need to increase draw strength try moving the injector closer to your trigger. For example, at 300’ of high pressure hose with the injector at the machine you have a limit to how strong of a pull you will get from any injector. Simply moving it forward 100’ or 200’ closer to your trigger will almost double your draw.
1. In line with that, any accessory that is worn out creates an extra restriction. If your trigger is weeping, qc’s are leaking, crimps are rusted inside etc. these will all decrease your chemical draw.
2. Injectors are wear items. They need to be replaced regularly and can wear out pretty quickly when the components aren’t rinsed. Keeping a spare injector on the truck and replacing them at the first sign of failure will keep you hitting the surface with a consistent ratio, giving you consistent results.
3. Injectors are not an exact science. If you have tried all of the above and still are unhappy with your draw strength, try an injector with a smaller orifice. For example, test the draw strength of a 1.8, 2.1, 2.3 injector regardless of your flow rate.
4. Some other alternatives include switching to a high flow injector, dual barb injector, or even to an xjet style tool. As they are all designed to increase your draw strength from a standard inline injector you should instantly see a difference in draw strength.