firing injectors ... manually

[Chris2012]

There's a lot of different checks you can run on a car. I have 1 or 2 "standard" check to perform as of yet. Thanks for the suggestions. But it occurred to me that applying a constant 12vdc? To 1 injector, or the remainder of the circuit after you pull a plug beside the plenum would help to entirely eliminate the injectors themselves as the problem. Alternately I could "pulse" them with the 12 volts by quickly touching a wire where it matters. The polarity would need to be correct, no? I have 1 guy telling me the resistance of individual injectors.or entire circuit can check out, but they'll still fail in operation. Is this true? Anyway if I did manage to fire the injectors (or not) while cranking or just with key ON and sniff for gasoline, it would tell me a lot. Whaddaya dink?

 

Also, should I knock the voltage down a bit with a resistor, or is the full 12vdc ok?

[skitchin]

I don't know the specifics, but all together this sounds like it might be a bad idea. Particularly the part where you'll be touching wires together, creating an electrical arc near a fuel injector.

 

I also doubt the pulse signal would be a full 12v. I don't know what I'm talking about when it comes to injectors though, but I'm just saying.

[Schurkey]

First Guess: Putting 12 volts to them will burn the solenoid coils.

 

GM (Kent-Moore/OTC) had a "special tool" to fire gasoline fuel injectors. They show up on eBay fairly often. Prices vary wildly. One drawback is that unless you test the injectors individually, there's a heap of special harnesses needed which change depending on the vehicle being tested.

 

http://www.ebay.com/itm/KENT-MOORE-TOOL-J-39021-FUEL-INJECTOR-COIL-BALANCE-TESTER-/171156898476?pt=Motors_Automotive_Tools&hash=item27d9bf02ac&vxp=mtr

[RobertISaar]

12 volts will be fine on the injectors.... after all, that is what they get in normal operation. having 12 volts applied for long periods of time, that will cause problems. i've run some for up to a minute at a time with no obvious failure.

 

that being said, with a LH0 at idle, the injectors are on for roughly 2mS once per revolution.... so if you are sitting at a 600RPM idle:

 

engine completes 10 revolutions per second, so a period of 100mS and the injectors are on for 2% of that time.

 

no one's hands will move that quickly. keeping the circuit powered for 4mS instead of 2 makes the AFR shoot from ~14ish to ~7ish.... which means you will easily drown the engine with fuel at idle, risking hydrolocking the entire time.