question on testing/cleaning injectors

88911coupe · 12-01-2008, 06:15 PM

Another post about a home made injector test rig got me tinkering and I put together a rig of hoses hooked up to a bike pump with a pressure guage. I'm able to put about 35 lbs of pressure into a tube holding a bit of carb cleaner then I briefly hook up a 9V battery to the injector and it fires a perfect mist of carb cleaner. Here's my question...
Am I doing any damage with the 9v battery if it only pulses for a brief instant?
TIA

Bart_dood · 12-01-2008, 08:10 PM

I guess your question is: am going to overheat the injector coils by having them on longer than the car does?

I doubt it although it is difficult to know definitively, you could hook up a variable resistor in series and start high and work lower until the injector opens, this will minimize the current to the lowest level that will trigger the injector.

88911coupe · 12-01-2008, 08:15 PM

Well I was only letting them run for a brief instant, less that one second for each "burst" and I'd wait a few seconds between each shot so it's running at what I would think would be a slower rate than if it was in a running engine. The web site that got me thinking about doing this was using a 12v source so I assumed a 9v source would be less stressful but maybe I'm missing something about electronics.
My main goal was to just get some carb cleaner though the injectors to make sure they were cleaned out before I reinstalled them.

Bart_dood · 12-01-2008, 08:19 PM

I think you'll be fine, it sounds like the duty cycle you are running at (20%) should be no problem at all.
Do you think the carb cleaner is helping the injectors? I might be tempted to clean mine this way also.

88911coupe · 12-02-2008, 09:19 AM

It appears that the 2 I tried this on so far were in pretty decent shape. At 35 lbs of pressure I was getting a shot of carb cleaner mist that basically evaporated instantly. I took a large piece of heater hose tube (5/8"?) that just happens to fit perfectly snugly over the end of the injector with the oring in place. I found another piece of fuel line laying around which had an OD the same as the ID as the larger pice and cut off a 1" section which I slid it in the other end, basically necking it down enough to get one of those cone shaped adapters that come with airpumps to fill up various toys . I stuck that into the necked down end and put a worm gear clamp on it and pumped it up to 20-30 lbs initially and it held the pressure perfectly. Then I removed it and shot a nice dose of carb cleaner into the tube, reinserted the cone adapter and pumped it up and let the end with the injector hang down so the cleaner would sitting on top of the injector and be pushed through when the injector was powered. I then just hooked up a speaker wire to the battery terminals and briefly touched the injector spades and it shot a mist of carb cleaner out perfectly. I'd let the cleaner stay in the injector for a few seconds and fire it again. I was thinking it may be a good idea to leave some injector cleaner in there for several minutes.
I also thought about shooting some though "backwards" but I don't know if the injector is set up to handle pressure coming from the opposite direction...
I did notice that when I bumped the pressure up to 35 lbs the mist was much finer so I don't know if that's the pressure that results in a good mist or whether the first few shots actually cleaned it up a bit.