Running fuel injector outside the engine

Question

I want to use an arduino I have lying around to make a fuel injectors tester/cleaner. It looks pretty simple, just connect the injector to a battery and the pin that goes to the ECU to a pulse generator.

But I don't just want to hear them "click", I want to see them spray fuel, so my question is. So my question is, is feeding them fuel by gravity enough, or do I need to use a fuel pump to generate some pressure?

Answer 1

Well, gravity does create pressure. Put the container high enough and you have hydrostatic pressure.

However, this is impractical. 10 meters equates to 1 bar for water, and for fuel the density is lower so the hydrostatic pressure of 10 meters is lower.

For optimal fuel flow, you need several bar, meaning several tens of meters. That's too high for practical testing. This is why I suggest using the full fuel system, i.e. fuel pump without forgetting the all-important fuel pressure regulator.

If the system happens to be a common-rail diesel, do note that:

1. Diesel injectors are extremely expensive, so you don't want to play around with those.
2. Diesel injection pressure is very high, typically several thousand bar, so high that it is indeed dangerous. I repeat: you don't want to play around with those!