How can I check to see if injectors are pulsating?

CaifanSC

SCCoA Member
I have the fuel rail detached from the manifold, if I want to check if the injectors are actually pulsating and spitting out fuel...what can I do?

By switching the key to ON I get nothing...do I have to actually crank the engine for them to fire? Is there another way (i mean, i have the supercharger out and all sorts of stuff disconnected, so i dont think i can crank the engine like that).

I have a pressure leak in the fuel system and I figured it would be the injectors, but when I prime the system and make the pump run I dont see any of the injectors leaking!:confused::confused: I did find that two of the injectors on the drivers side had the tip completely destroyed...the pintle caps were actually detached from the injector its self. I get 40 PSI of pressure when the pump is running, but once it stops the pressure just colapses back to zero. Any thoughts?:confused:
 
Sounds like a bad fuel pressure regulator is possible if pressure immediately drops to zero. If everything was hooked up you could use a noid tester. They are little devices that attached to the injector wiring and detects when current is passing through them. They light up. But the engine has to be cranking for that to happen.
 
I would say that your fuel pump is bad. If you want to crank the engine over, make sure that all of the dirt and debris is away from any entrance to the engine, and disconnect the coil pack so that you do not have any fire and crank away. Also be sure that you do not have any rags stuffed into any entrance to the engine. If you have any questions, give me a call tomorrow evening.
 
Duffy, the fuel pressure regulator is actually brand new.

Patrick, the pump is brand new also, and would a faulty pump still pressurize to 40 psi? Im getting constat 40 psi for as long as I have the pump on, so i duno.


Any other suggestions? :confused::confused:
 
If your injectors are what is leaking, they would leak just by turning the key halfway I believe. If pressure immediately drops down after key turned and you see nothing leaking from injectors, then souns like you have a pump problem . Warranty?? That would be nice again.
 
Is it possible that I hooked up the pump wrong? Or that I wired it wrong? What happens if you switch the polarity in the pump?? Im just curious because the pump was brand new. I bought it a while ago and was waiting for it to go on my 89, but since this came up I used it but the warranty is probably done by now.
 
If you plugged the return line as I suggested in your last thread, you'd know if it was the regulator or not.

you may test the signal going to the injectors with a 12v led or a few in series. But the crank has to be turning while testing. unplugging the coil pack harness should prevent any fires.

Why did u swap out the regulator in the first place?


Hope this helps
 
if you decide to plug the return line, a nail can be used as a plug between the rail and return line. Just be super careful as their is a lot of pressure in those lines, more so if u plug the return line.
 
turn the engine over by hand with the ignition key in the on/run position and the injectors should fire. If they are still fitted to the engine, you should be able to hear them if you listen carefully.
 
If regulator is new & no injectors are leaking, you need to check the pump. You do need to crank the engine to fire the injectors, but if you're just looking for the pressure bleed down, you don't need to do that as they will leak as soon as they get pressure to them. The noid lite will tell you there is current/signal to the injectors, but will not tell you if they fire. You can put a finger on them while someone cranks the engine and feel them moving internally if that's the best you have available.
 
I know theres a tool that garages have that lights up if the injector is pulsating. You pull the plug out of the injector and plug this tool into it and if it flashes that means its pulsating. You may want to pull the tank put the pump in a bucket and see what is really happening when you turn the motor over.
 
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