how does our fuel system work

[broncobilly_69]

I understand the the fuel being injected into the precombustion chamber and all that but could someone explain to me the need for return lines and the plastic fittings with low pressure fuel around each injector. I can't seem to figure out he purpose of these.

 

[Exekiel69]

The amount of fuel needed by the engine is not the same all the time so you pump a safe amount of fuel to the IP and it will inject what is neccesary at the time. Maybe that is not it, but is what I can offer right now.

 

[icanfixall]

The diesel fuel has 3 uses. First its what makes the motor run. Second it acts as a lubricant for the injection pump. And lastly it acts as a coolant pulling heat away from the injection upmp and injectors. Dome here will run their trucks out of fuel just to see how many miles per gallons they get. Now the injection pumps cost around $400.00. Do you really want to run it out of coolant AND lubricant???

 

[Agnem]

The return lines exist because not 100% of the fuel that is sent to the injectors is injected. The presure that is required to overcome the spring in the injector is greater than the initial and post injection presure present in the injection line.

 

[broncobilly_69]

The return lines exist because not 100% of the fuel that is sent to the injectors is injected. The presure that is required to overcome the spring in the injector is greater than the initial and post injection presure present in the injection line.

how does the fuel get from the injectors into the return line? I don't remember there being a hole in the side of the injector that would act as an inlet into the return lines, then again I wasn't looking for one either, when I replaced the retrun lines.

 

[sle2115]

When the injector is closed, any fuel that doesn't have enough pressure to overcome the spring tension needed to open the injector, is bypassed and goes back up through the injector and into the return t's and then back to the tank. When the pressure overcomes the spring, forcing the injector open, the pintle blocks the passage to the return side of the injector, forcing fuel into the cylinder until the pressure drops below the spring pressure again (somewhere around 1800 PSI if I remember correctly) and the fuel again goes the route of the return t's. Kind of simplifying it, but I think you'll get the idea.

 

[sle2115]

You might want to check out this thread - "Let's Talk Injectors"

 

[Agnem]

Yes if you look at an injector you will see holes between where the rubber O-rings lay. That is where the fuel exits.

 

[broncobilly_69]

Thanks guys. I got it figured out now. Just like to understand how things operate.