Injector Leaking.

[rcb280z]

So my #4 injector is leaking into the engine of my 77 280. Yesterday I removed all the plugs just to look at them and discovered #4 spark plug wet with fuel. Smelled only of fuel, not oil. I have a replacement injector on its way. Now I'm trying to figure a way to fire the injectors with the whole rail removed from the intake. Want to see spray pattern. In theory I should be able to "energize" the injectors by manipulating the AFM flap and the injectors should spray fuel correct? Or is that only through the start circuit? In other words what would be the best way to energize the injectors to spray for me so I can observe flow.

[Zed Head]

They would only spray at every third spark.  And you probably don't want external sparks while you're spraying fuel, so messing with the coil and ignition would not be an option.

 

Another way to do it would be to run a jumper to ground from every injector pin at the ECU connector.  With the key on there should be power to the injectors, grounding them like the ECU would do should open them up.  Run the grounds, turn the key on, the injectors open, open the AFM flap and the pump makes them spray.  I have not tried this but it should work.

 

Are you looking for spray pattern or do you want to measure output?  Because the spray pattern of the stock Datsun injectors is essentially a thin stream.  If you're using Bosch injectors, you'll get more of a mist.  If you just want to check for leaks, then the AFM-flap method would run the pump and pressurize the rail.

[rcb280z]

Yes, I am really just looking for leaks. Although if I go by my other spark plugs there shouldn't be any other injectors leaking. The other plugs are dry.

And the injectors I use come from Beck/Arnely so I dont know the spray pattern on them anyway. 

Ok, more trouble than I thought. Just going to replace the one injector and be done with it.

 

I replaced these injectors 2-3 years ago using the FJ707 one's that several members used with no issues. Can't wait to see the cause of the leak if I can even tell what it is.

I know my fuel is clean...no rust. But am wondering why it's leaking. Quality of part?

 

Thanks ZedHead.

Edited February 28, 2015 by rcb280z

[siteunseen]

I'll be anxiously waiting for the cause, if it's obvious, I put those in my '77 a couple of years ago as well.  When you get the bad one off you can test it's flow on your workbench according to this video.  

 

Mine were Standard FJ707Ts with an open style pintle instead of the little hole.

 

[Captain Obvious]

I'm not coming up with any real easy to fire them using the car as a test mule.

 

I'd be wary of connecting wires to the pins on the ECU connector. That would work, but you have to be very sure that you don't make any sparks there, and if you're making and breaking connections with a wire, you run the risk of making sparks which will damage the connector pins. Order of connection and connection integrity are important.

 

Have the rubber booties on the back of your injector connectors rotted and fallen off yet? If so, you could easily determine which wire goes to the dropping resistor and which wire goes to the ECU. Once you know that, you could stick a wire down into the back side of the injector connector on the ground side and intermittently connect the other end of that wire to ground.

 

Turn the ignition to run, block the AFM open (to get the fuel pump to run), and when you ground the other end of the wire that injector will fire.

 

In fact, three injectors will fire because of the way they are connected together inside the ECU. Two wires on two different injectors and you could get all six to fire.

 

Sorry, not pretty, but that's the best I got.

 

 

[rcb280z]

Siteunseen, I should be able to "juice" the injector with a 9 volt battery. Going to put it in my bench vise, put a 12" piece of fuel hose on the injector, add compressed air (about 40 psi), and power it with a 9 volt battery. The reason for the 9 volt, I've been told a 12 volt source can fry the injector. So I'm going with that unless someone here tells me different. Hmm...if its leaking I may not even need the battery. The compressed air will probably make it leak, just as if it were on the fuel rail with the fuel rail pressure huh?

 

Capt., I replaced all connectors and wiring for my injectors when I replaced my injectors a couple years ago. I'm with you though, I'm not comfortable with messing around the ECU pins, etc. 

Edited February 28, 2015 by rcb280z

[Captain Obvious]

Sounds like a plan. Just don't leave the power connected to the injector for very long. The injectors aren't designed to stay open for long periods of time, regardless of what you're powering them with. It's not the voltage that's the problem. It's the amount of current. But the reason a 9V might be safer is that it just simply isn't capable of supplying the vast amount of current that you can pull out of your 12V lead acid car battery. But you're right about the leak... If you're looking for a leak, you won't even need to open the injector. 40 PSI air and dunk it in a container of water and look for bubbles.

 

Of course, seeing the spray pattern is interesting too, but if you're focused on the leak, it might not matter.

 

My prediction? It's an intermittent leak. Sometimes it will close completely, and other times it'll remain open a tiny bit resulting in a "seeping" kind of slow leak.

[Zed Head]

You could wire it up and make the final power connection last.  I make individual connector pins by pounding a piece of solid copper wire flat.  Sticks right in there, converting female to male.  Then I use alligator clips.  Does take a little extra care though and can make you nervous.

 

If you're just looking for leaks, then pressurizing the rail and injectors would work.  If your FPR and pump check valve are working the rail will hold pressure and you only need to run the pump for second or two.

 

I diagnosed a neighbor's injector with shop air.  Even with a leak there was enough leftover fuel sitting in it to get pushed out.  The body was cracked and it leaked externally.  It was an old Porsche injector, that apparently is known for doing that and burning up cars.

[rcb280z]

Thanks for the info guys. Will let you know what I find.

[EuroDat]

Hi Bob,

Im a little late, but maybe it will help you a little.

I had a problem with to lean cyclinders a couple of years back. I did a simple (ans I mean more crude than simple) test to see if the injectors were the problem.

 

Basically I removed enough of the mounting fixtures so I could get the injectors and fuel rail up high enough to see the tips clearly.

Then I found some plastic cups from a local store "Action" (what you could call a $2 dollar shop) and strapped them onto the injector tips.

Removed the spark plugs, rigged the AFM open and cranked the engine for about 20seconds. I didn't go to long on the starter. Didn't want to burn it out.

It was enough to see number 4 was amost blocked, number 3 partly and number 2 was maybe a small amount. See last photo: left nr 1 to right nr 6.

 

After that I reverse flushed them with a long hose full of fuel mixed with injector cleaner, air compressor and a 9 volt battery to trigger the injector. Kept repeating the flush until they where all flowing ther same amount in a beaker.

 

Good luck finding you problem. If you need more photo's or info let me know. Glad to help.

Chas

Edited March 1, 2015 by EuroDat

[Captain Obvious]

Chas, That's a great method for checking the flow balance.

 

 

 

[rcb280z]

Chas, you may have just helped me change my mind and check flow of my injectors. I was thinking about it yesterday while my wife and I were hiking in the Los Padres National Forest. That was loads of fun BTW.

I was just thinking that I may as well check flow also because I'm going to have the fuel rail off of the intake. If I'm that far into it I may as well check everything. On your cups, what did you use to seal the tops? Is that some sort of tape?

And did you remove the cap and rotor from the dizzy so there was no spark? 

Edited March 1, 2015 by rcb280z