Found out one of my injectors are leaking...

[Black1987Stang]

I brought my car in the shop at school today to do a injector balance test but before I even did that i primed the fuel pump (grounded the terminal) and with the pump running (40psi) I hear some little random occuring spurts, sounded like PSSH PSSHH Leaking?..The pressure will drop from say 40psi to 0 in like in less than a minute. ( brand new pump so its not the check valve) It was only coming from one injector (#2)...I guess this is why my oil is getting dark so soon and why im getting like 12-13mpg with stock 19lb injectors? Anybody have experience with a sound like that? or comments

 

[90mustangGT]

This can happen, but that is a slight leak, not an fully open injector. Consider cleaning the injector, a small partical might be preventing the plunger in the injector from fully closing.

 

[SamSnyder]

Don't know about one mis-firing into the port, but I've seen one cracked and blasting its fuel on top of the motor. Big mess, smelly and dangerous. Did you do the EEC IV engine running cylinder balance test? It's a built-in diagnostic routine in the EEC IV system and should definitely confirm which cylinder is leaking under the facts that you described. You first run the EEC IV diagnostic test using a code scanner or paperclip, and within a few seconds after the computer runs all its tests on the sensors and such, it will run a cylinder balance test of the injectors if you trigger it by kicking the throttle off-idle. The computer then sets the engine running at around 1200RPM, and shuts off each injector in sequence, measuring the resultant RPM drop. After all eight injectors have been tested, it bleeps out a code to let you know which, if any, of the injectors isn't living up to expectations. You can even re-run the test and it will narrow the expected RPM drop, revealing weak injectors that passed on the first run-through. The EEC IV computer is pretty smart in my book. But it is really designed to find the kind of problem you suspect.

 

[Black1987Stang]

Don't know about one mis-firing into the port, but I've seen one cracked and blasting its fuel on top of the motor. Big mess, smelly and dangerous. Did you do the EEC IV engine running cylinder balance test? It's a built-in diagnostic routine in the EEC IV system and should definitely confirm which cylinder is leaking under the facts that you described. You first run the EEC IV diagnostic test using a code scanner or paperclip, and within a few seconds after the computer runs all its tests on the sensors and such, it will run a cylinder balance test of the injectors if you trigger it by kicking the throttle off-idle. The computer then sets the engine running at around 1200RPM, and shuts off each injector in sequence, measuring the resultant RPM drop. After all eight injectors have been tested, it bleeps out a code to let you know which, if any, of the injectors isn't living up to expectations. You can even re-run the test and it will narrow the expected RPM drop, revealing weak injectors that passed on the first run-through. The EEC IV computer is pretty smart in my book. But it is really designed to find the kind of problem you suspect.

Thanks for the reply, I no about the cylinder balance test and all that. Its not gonna show up with that test, all it does is look at the drop in rpm each time it drops the injector(ive also tried it already too). all i did was run the fuel pump continously(engine off) by grounding the fuel pump test terminal and i could hear random PSHH noises like the injector was spraying or something, i even disconnected the harness and still the same, checked the resistance and it was the same as 2 other good ones so the coil inside is good..at least i found why my pressure is dropping too quickly and why im getting crap for mpg and why my oil is getting dark real quick (gas) o well i can get another set for like 20 bucks, or just throw in my 24lbers if i have to.

 

[DMAN302]

I would check the fuel rail bolts to ensure they are in place and the injector is properly seated in it's port..if all appears fine from there you may want to swap out the injectors..your combo would take the 24s just fine with the proper maf in place..the fuel bleading down into the cylinders is not goin to be a good thing IMO...it will make it's way into the pan and contaminate the oil.

 

[Black1987Stang]

I would check the fuel rail bolts to ensure they are in place and the injector is properly seated in it's port..if all appears fine from there you may want to swap out the injectors..your combo would take the 24s just fine with the proper maf in place..the fuel bleading down into the cylinders is not goin to be a good thing IMO...it will make it's way into the pan and contaminate the oil.

Yup the rail is on there nice and tight. I did have the 24's on there for a while but i switched back to 19's cuz my maf was acting up on me(i think sensor was just dirty) and for any slightly better mpg I could get. When i get time ill pop off the rail and with the rail pressurized see if it is truly leaking and go from there I guess.