Operation of Injectors

I've got a quick question on how the injectors are supposed to operate, on my 81 1.6 GTi.

I've pulled all 4 injectors out of the inlet manifold, and given them all a good clean. When I lift the little nozzle bit at the end (with a screwdriver) fuel squirts out as it should. However, when I turn the engine over, no fuel squirts out, unless I lift the little nozzle bit again.

Is this the correct mode of operation (I'm not convinced)? If not is there an easy fix? Or even a quick but expensive fix?

Any help would be very much appreciated

Thanks

Rich

what little nozzle thing do you mean? lifter plate (disc) above the air filter?  :dontknow:

could have an air leak somewhere because (my understanding) the liftplate gets sucked up when turning the engine over/accelerating etc. causing that 'pin' in the metering unit to go up and open the fuel to the injectors

when you lift the plate and drop it, does it bounce? and is there any resistence lifting it up?

the injector's only start working when there's enough fuel pressure behind them.. sounds like something's stopping the fuel getting to them which will either be the metering unit or not enough fuel pressure

might be something else I've forgotten :dontknow:

Sorry Phil - I wasn't 100% clear in my previous explanation…

I think the metering head and that flap which operates against it (just above the air filter) is working fine.

The little nozzle thingies I was referring to are on the end of each injector - when I left those the fuel comes through the injector, but otherwise nothing flows through them, even under starting conditions.

I did wonder if low fuel pressure might be the cause - but the lines are brand new, and so is the pump and the filter. Could a small blockage in the tank be the cause?

Thanks for the advice though dude

Rich

Have a look at our Injector Test
…the air flap has to be lifted to get fuel through the injectors….

I would be very careful playing with the 'pintle' (valve) of the injector - I've ruined a couple by doing that…..damaged the spring and ended up jetting all over the place….!!!!

the injectors are sprung so it takes high pressure from the fuel (about 80 psi i think) for them to open to inject hence why they are continuos injection flow is controlled by the metering unit

the injector test is great

Stuart

Thanks for the info and pointers guys - very much appreciated :y:

I'm more confident now that the injectors are operating as they should. Going to try replacing the coil now as there is definitely fuel getting into the cylinders, even without the 5th injector connected, so I'm hoping it's a weak spark that's the trouble.

Once it's running I'll move on to measuring the flow…

Ta muchly again

Rich