stuck injector tricks?

[944Spec_bound]

Anyone know a McGuver way to free a fuel injector thats stuck open without removing it? The car hadn't been started for about 6 mos, so I'm thinking it's corroded in there. I tried tapping on it while engine was running, no luck.
Would injector cleaner fuel additive do anything?

[944 boy]

I had one stick. I pulled it out and wiggled the needle and hit it with a blast of compressed air. Worked great ever since.

[HondaDustR]

Seafoam.

[Zero10]

Doubt anything without removing it would work. Anything you put in the fuel will have a really hard time getting to where the injector is stuck because there is no fuel flowing through it. I'd say it is more important to find out _why_ it is stuck.

[175mph951]

use power probe and alternate + - from each side a few times

[mikepellegrini]

For a longer-term repair - For less than $100, Witchhunter will clean and replace all the replacable o-rings, and flow-match 4 injectors. Basically, it's like new injectors...

Their turn around is less than a week. They did the injectors on my 951 and I'm really pleased with the service.

http://www.witchhunter.com/index.php4

And it only takes 5 minutes to pull the fuel rail...

[944Spec_bound]

confession: the stuck injector isn't on the Porsche. It's on my son's 300zx, and they're under the plenum so they can't be easily removed. I figured with the knowledge pool in this forum, someone would know a trick or two. If i can save several hours working on his rice-burner, it's several hours I can put into my car prep.
I'll try the alternating DC onto the terminals suggestion.

[Zero10]

With the alternating DC trick, make sure you only connect the wires for a VERY short time. A trick a lot of people do is to use a 9V battery not a 12V battery, this helps because.......

Fuel injectors are solenoids. When you first apply power that energy goes into producing a magnetic field, that magnetic field is doing work, and while the magnetic flux is changing it produces a counter-EMF in the coil wire inside the injector. This counter-EMF serves to reduce the overall current flow through the injector coil. This means, for the first split second the injector is connected it draws only a small amount of current.
Once the needle / solenoid component comes to a rest (the click you hear) the magnetic flux is no longer changing and the current draw increases DRASTICALLY, since it is now simply a resistor and not an inductor. If you leave +12V connected for this time period the wiring will heat up to the point of melting the insulation in a very short time (varies by injector, but it can be as short as 1/2 second), then the injector will develop an internal short and no longer function properly.

By using a 9V supply you increase the margin of time you have by reducing the rate at which the wiring heats up.

This is why injector cleaners use a very high frequency short duration pulsed power supply.

*EDIT*
Oh yeah, nobody will knock you for working on a 300ZX, as long as every time you get in your Porsche you apologize to it.

[krystar]

well..only if it's a 300zx NA. 300zx turbo would get the ok in my books.

[brian944turbo]

I just replaced the motor in my 90 300-zx. Have extra injectors, coil packs anything you need other then the lower end. Your welcome to them if you have to take it apart. Think I also have injectors for 85-86. Brian

[SolReaver]

Ok, Get a 9v battery from radio shack and one of those caps to go on it with the two wires sticking out. Put the two wires to the terminals and listen for the clicking. A little 9v battery doesn't have the ability to fry an injector, which is why I prefer them over the 12v from a car battery.

If this doesn't do the trick, you probably have to take the thing out and pursuade it with compressed air, soaking in penetrating fluid and a few raps from an intimidating hammer. (not on the injector tip)

The witch hunter guy is top notch. His service include "flow matching", very cool.

Don't let the Porsche see you working on the 300, or it will get jealous and want more attention.

[larrym]

i just had this stuck injector problem on a 3.2 carrera - 3 were stuck & preventing start-run (engine longtime in storage)

I have a pro tool called an "injector inspector" that does the pulsing - but you can also do it this way

from Z-car:

"Anyone ever free up stuck injectors??
Use a battery maintainer.

Wire a battery maintainer in series with the fuel injector and a battery, (the maintainer wont turn on unless there is some voltage).

The maintainer will put out a 60Hz pulse with a 50% duty cycle, this fires the injector rapidly.

Also the maintainer shouldn't put out more than 2 amps.

As I remember from a voltage divider and solving for current the stock injectors operate on about 2.2Amps.

Also you can use some of your favorite solvent (brake parts cleaner has worked for me). Fill the hose attached to the fuelinjector and let it gravity feed. You will see the solvent come out dark and varnished smelling the first couple of doses, and you will see the solvent come out cleaner after a few times."

stuck injector tricks?

[redstrosekNic]

Originally Posted by HondaDustR

Seafoam.

+1 on that!

[zedsn]

If the 300zx is a 1990 or newer you are going to have many hours in this job and I would only recommend buying nissan injectors and would replace them all at the same time. If you don't do this you will be sorry.