Have 2 injectors leaking on my 77 280. Took a few days of troubleshooting to figure out why my Z seemed like it was loading up on a cold start up. Pulled the plugs yesterday after Z sat over night and found 2 of them wet with fuel. So, I can't decide if I want to just replace them or have a fuel injector service done on the car or pull them and send them in to be rebuilt. Anyone have negative results? One's that you regret? Thanks.

Have you tried any of the injector cleaner products? Maybe all you need is to get the orifice cleaned so it can close. Also, make sure the injectors are operating. New injectors are very expensive compared to a bottle of injector cleaner. A clean fuel system is a happy system, and a healthy engine.

Yes I have used and do so periodically the Lucas brand. But I do recall using Techron for awhile and maybe I shood give that another try. I also think part of my problem is I hardly drive it. Not sure if that matters or not. Come to think of it I just changed out the fuel filter about a 1 1/2months ago. Maybe some crud got by it somehow. Thanks for the info

It's guaranteed what caused the problem is incredibly simple, like a bit of dirt or rust in the injector tip, but sometimes finding the problem isn't.

I built an injector flow bench and did lots of tests.

The best results were obtained by holding the injector open and back-flowing.

I also found that ultrasonic cleaning did not make a significant difference but it could have been my cheap $40 ultrasonic cleaner.

You can clean your own injectors by using injector or carb cleaner and the straw while opening the injectors. A 9 volt battery and clip-on injector connector with a momentary switch will do the job nicely.

It's too bad the injectors are just to darn difficult to remove individually.

Thanks Tomohawk and Blue for the help and idea's. I'm going to remove my fuel rail because I will be replacing my FPR and will probably rig something to clean injectors. I may remove the rail and pressurize it. I want to actually observe the leaky one's in action. Clean them and pressurize them again to make sure they don't leak. I should mention I'm replacing the FPR because it is about twenty years old and I will have the rail off anyway. Plus I already have a new one I bought 2 years ago. Will post results after I complete this. Hopefully in a week or two.

The best results were obtained by holding the injector open and back-flowing.

Genius!

As for the so-so ultrasonic cleaning results... Did you hold the injector open while it was in the ultrasonic bath?

Do the early Z's have filter screens in them? It's been many moon since I messed with 280 injectors.

This is how I do it:

http://www.classiczcars.com/forums/showthread.php?37098-Injector-testing-question&p=314509&viewfull=1#post314509

It's too bad the injectors are just to darn difficult to remove individually.

Nissans newer injectors are side fed and mount into the fuel rails in such a way that you can pull them individually. Great idea. However...:mad:

[RANT]

So they go through all that effort to design injectors that can be pulled individually without messing with any other part of the fuel rail, and what do they do on the 90-96 300ZX??? They put that big stinkin' upper plenum on top and make it impossible to get the freakin' injectors out without pulling ten million vacuum lines, sixty throttle body coolant lines, fifty-nine thousand electrical connectors, all the DIS coils, all the PCV plumbing.........:stupid:

And once you can even GET to the injectors, they are so snug into the fuel rails that it takes a space shuttle worth of upwards force to the them OUT of the rails.

[/RANT]

OK, I feel better now.

The bottom line is... If think the 280 is a pain, try a 90-96 300ZX!

Or a 2.9 L Ford Ranger, a 3.0 L Lincoln LS,....there's a considerable list of vehicles where removing the injectors is a pain. Comparative to some I've encountred, a 280Z/ZX isn't really that bad.

I thought the injectors are supplied with 3 volts from the dropping resistors to open them. I would have thought 9 volts was too much power. Hmmm, that makes it easier for me to rig something. Great idea's here. I love this forum! Blue, how did you back flow? Did you just spray the "cleaner used" into the oposite end of the injector, through the nozzle out the hose?

Edited January 16, 201213 yr by rcb280z