Just curious...trying to think of how to make an "off vehicle" testing device for injectors. If anyone knows, it'd be helpful.

 

Just make a simple 12v PWM circuit... with a mosfet driving the output probably about a 6a style one just to be sure.

That´d be more than ample to drive an injector tester.

 

Here's what I did, pretty ghetto, but it worked as a flow tester...

1) make a circuit for the injectors out of some wiring, using a spare car battery if available. Simple positive/negative circuit, with small female terminals at the ends for the injector pins (insulated, so they don't short together). Install a push button switch into the circuit, if desired, so that you're in control of the opening times of the injectors.
2) Run some hose, about 3/8", up the side of the house, garage, a pole, whatever, the longer the better. Let gravity work for you, basically. I used normal air compressor hose, about 8' long.
3) get a funnel for the top of the hose, and attach an injector at the bottom of the hose, much as it would go into a fuel rail. Use a small tie-wrap to help keep the injector in the hose, if needed. Place a container under the injector for the solvent, if desired.
4) get a good solvent (I used acetone) and fill the hose from the top, using the funnel.
5) place the terminals on the injector pins. Polarity shouldn't be an issue, but just in case I figured out which pin was positive in the car's setup, and used positive from the battery there (left pin of the injector, but don't quote me on that, it's been a while, lol)
6) Push the button of your circuit tester. The injector should click and flow. Depending on initial hose length, you probably won't get a spray pattern out of it, but it will definitely come squirting out of there. The acetone should help clean the injector. Push the button on/off as fast as you can, to simulate normal injector cycles, and have some fun in the process, lol...
7) drain the hose, remove the injector, install another, refill the hose, and go to town again
8) I also noticed that if you poured some acetone into the injector, placed your fingers over the openings, and shook it like a paint can, then emptied the injector by energizing it to open it, some pretty gunky crap came out of there

 

I'm wanting to run a test using 40psi of pressure behind the solvent. I thought that 12v would be too much for the injectors to handle...thought the voltage was cut becak some.

 

What do you think powers the injectors while running? 14+ volts...

A little basic electricity 101: The injector coil is going to use the same amount of power whether you have it hooked to a fresh car battery (say 550 amps), or a bunch of D-cell batteries connected in series to get the 12v. The coil will only draw so much power due to it's design, as long as the source voltage is around 12v. In other words, it's going to draw 100 milliamps (just pulling that out of my butt) from the car battery, or from the D-cells, it doesn't matter....

Now, the low-imp injectors might be a different story, if not using the resistors, because the 2 ohm coils are damn near a short, as far as the battery's concerned. Then again, once the coil's EM field builds, it'll be acting as a heck of a lot more than 2 ohms (that's what impedance is all about)...

 

sorry guy, not everything in a car is run on 12v.

 

You say that as if voltage means power. Voltage is only the potential for power to flow, it is not in and of itself a measure of the amount of power used by a circuit. It's like a waterfall- the higher the water is, the more force (potential for work) is at the bottom. 120v at 1 amp is the same amount of power, in watts, as 12v at 10 amps.

The only thing I can think of off-hand on the car that isn't designed for a 12-15v input would be the 5v sensors for the ECU inputs...

As stated earlier, the low imp injectors might be a different story, because the resistors will drop some voltage in the circuit. How much? I dunno, but give me the resistance values and the current flow of a single injector circuit in amps and I can work it out...You have a '90 in your profile, so this is a moot point.

Any 12vdc source will work for testing your injectors, as long as the amp-hour capacity of the source is sufficient to overcome the inductive impedance of the energized coils...In other words, 8 D-cell batteries strung together might not cut it

 

True.....but the fuel injectors are for SURE.

 

Exactly, and the reason the resistors are put in the circuit for LI injectors is to reduce the current flow thru the ECU.

 

http://www.bgsoflex.com/fitester.html
-John

 

Shazzam! I ressurect this thread in the name of cheap-assness (that's a real word, look it up sometime).

I have some spare injectors from my 87 GXL that uses the resistor pack. I'm not a FI wizard, but I'd like to try your methd to clean out my spare injectors Wayne.

I just wanted to see if anyone had some fresh ideas they'd like to bring to the table involving this process. It sounds pretty simple though.

- Connect a button between the injector and battery.
- Push button alot to make the injectors pump
- ...profit.

I don't think I'd do this if I had a turbo vehicle in fear that they'd fail and I'd detonate, but I'm cheap and own a N/A, so I'm willing to try it in the name of saving a buck or two.

 

I've tied the injetors to the secondary fuel rail wth zip ties and run wires to the pos/neg battery calles from the fuel injectors on the secondary fuel rail

I put a graduated container under the fuel injector. Jumpered the fuel pump check connector. Turned the key to ON. Touched the the positive lead to the battery for a full minute. Then measured the container.

OH. The injectors did not burn up or get goofy on me after doing the above.

P.S. The resistors are there to protect the Drivers in the ECU, not the injector.

All in all the process kept me out of the bars for a weekend or two and that's about all it was good for. I did put a very large amount of injector cleaner in the fuel tank (tank about empty) so maybe I did some cleaning of the injectors. Ain't ultra sonic cleaning by a large shot.

 

Ah, so you basically did the same thing as Wayne but you put some pressure behind it.

I know this won't be as good as ultrasonic cleaning, but I premix and I'm sure my injectors are getting a bit dirtier then they normally would, so having a relativly clean set to swap every 15k miles or so would eb better then just letting them sit in there until they get so bad that sending them to a shop is necessary.

I'm thinking of it as more of a preventative maintenance type of thing.

 

Hey guys, what about one of these small ultrasonic cleaners for jewelry/etc? They're like $30 on ebay shipped....

 

Anything's possible, try it if you want. Just remember- when in the ultrasonic cleaner, unless you've got something rigged up, the injector is closed- how are you going to clean the poppet seat, which is where most of the gunk is probably going to be?

While gasoline is a solvent, basically, I prefer to use a dedicated solvent, such as acetone, or MEK if you really want some power. If you use Hailer's setup, please don't blow yourself up from the fuel vapors