Testing injectors on a car

I

ISG

Well-known user
May 30, 2013
122
17
Lithuania
Hi,

I suspect that some of injectors are not holding pressure (leaking). I will perform a simple test - take the rail with all injectors off, and engage the pump. They should hold the pressure and shouldn't leak a drop out of them, right?
So taught, since the rail with injectors will be taken out, maybe it is possible to check how good do they spray. What should I do? Simply crank the engine, and they should spray right? as long as I will crank it, the injectors should spray? Maybe someone will suggest, thanks!
 
I...I don't think it works that way. If you take the rail off the head, the injectors are only held in by the o-rings. You try to pressurise that setup and run the pump, you're going to end up with three injectors heading off in one direction, and three others heading off at a 60 degree angle to the first ones.

Either that, or you're going to end up with petrol all over the engine bay as the injectors either unseat and leak, or actually manage to spray it like they're supposed to (which is absurdly dangerous as well).

If you suspect you have leaking injectors, you must have a reason to think that. Is it misfiring? Can you tell on which cylinder? Swap them around and see if the fault moves or better yet - just replace the seals. Or the entire injector.
 
Ahh yes, if they are only held by the o rings, it wont work... Never had them taken our so dont know... I remember pulling out fuel rail from ford probe, and injectors were fixed on the rail, so you could take the whole rail and test it that way... Thanks, i will figure a way to do that... And regarding spilling the fuel - you just can use 6 small clear bottles, and put injectors to spray inside of them...
im having a hard start issue (another post of mine), it could be that one of injectors is leaking into the cylinder... Anyways, obd tester and fuel pressure test kit is comming to me in a few days, so i will diagnose thos more properly... Now i just gathering knowledge in advance :)
 
ISG said:
Ahh yes, if they are only held by the o rings, it wont work... Never had them taken our so dont know... I remember pulling out fuel rail from ford probe, and injectors were fixed on the rail, so you could take the whole rail and test it that way...
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Totally different engine I'm afraid. I don't know of any safe way of testing Duratec ones without a bench rig, though others might.

ISG said:
im having a hard start issue (another post of mine), it could be that one of injectors is leaking into the cylinder... Anyways, obd tester and fuel pressure test kit is comming to me in a few days, so i will diagnose thos more properly... Now i just gathering knowledge in advance :)
Click to expand...

I remember posting in that thread (I missed some of your diagnostic steps unfortunately and got it wrong - sorry about that). If you have a leaking injector, it may well be flooding a cylinder and causing a difficult start.

At this point, you might be best off hitting eBay and buying a complete set for £50 (219 LTL, since you're in Lithuania) and not wasting your time.
 
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