The forward injector on my '84 is not delivering fuel, but the aft one is. What is the test sequence to determine whether it is the injector or the wiring/ECM that is failing?
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Re: '84 injector not delivering fuel
You can use a tool called a noid light or a digital voltmeter to determin if it is getting the signal to turn on. This will tell you if it is getting power. I would guess that if one is working, that there is a problem with the injector or the wiring to it. -
Re: '84 injector not delivering fuel
I have a digital VOM. What are the values at the connector to the injector? What is the resistance thru the injector?Comment
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Re: '84 injector not delivering fuel
Without going to the books, I am not sure of the resistance. On later cars it is about 20 ohms. First just hook put the meter or a 12V light bulb across the wires to the injector, unplugged of course, and watch for current pulses.Comment
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Re: '84 injector not delivering fuel
Just went through this on my wife's acura integra. Resistance is not a good indicator of injector failure. I definately had a bad injector but the resistance checked out. I happened to have a digital multimeter that measured frequency from 0-500V DC. I plugged the two leads into each FI harness and the readings were constant. I belive most injectors are 12V.
I also used bubbas favorite method of holding the metal end of a screwdrive to the injector and the end with the handle to your ear. You should be able to hear the solenoid inside the injector clicking.
BrianComment
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Re: '84 injector not delivering fuel
With the '84 crossfire injectors, I don't have to listen for the injector to be working - I can see the fuel spraying! These puppies are like carburetors without a body, they just spray fuel into the manifold. I think I may have messed up the one that is not working - there are only two - by disconnecting the wiring while the engine was running because the other still works, and now this one doesn't even when it is reconnected. I don't know of any other solenoid that will quit working just because it is disconnected (whether it is in use or not in use at the time it is disconnected)! Makes me think it is not the injector (the reason I submitted the question originally) but the ECM. I do not have a detailed schematic of these, and wonder if there is a fuse on that circuit of the ECM. I do know each of these is powered thru a different circuit directly from the ECM.
That said, I appreciate the answers, guesses, and responses I've gotten. I don't want to spend $195.12 (plus tax) on another injector if it is the ECM. By the same token, I don't want to fork over $167.35 (+ tax) for a new ECM. Both are Chevy parts prices from my local dealer, but the numbers don't vary much going to NAPA or Car Quest. If I can determine the fault, I will not hesitate to spend - especially if there is a $1.50 fuse in the line from the ECM.Comment
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Re: '84 injector not delivering fuel
I dont think that there is a seperate fuse on each line, but it is simple to check for power on the circuit. Just use your volt meter. You should be able to tell instantly if there is power there. The computer simply grounds the circuit, so you can artificially do that too and make it fire. Or you can turn the key on and let the fuel pump power up. Put power from any source on the injector and watch it fire. I dont really see why unplugging it while the car was running would kill the signal from the computer, but stranger things have happened. As I said before, just make you a noid light out of a small 12V lamp. Solder two wires and plug it in. When you crank the engine the light will flash. Lets you know if the computer is working.Comment
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Re: '84 injector not delivering fuel
PROBLEM SOLVED! I had the time today to jumper between the working injector wiring and the non-working injector. The problem injector functioned properly. I then traced the wiring back thru the system and found that - indeed - there are separate fuses (3 amp plug-in) for each injector in the fuse panel. Replaced the fuse - injector is back to working properly. Also tracked down a vacuum hose that was not routed correctly. Runs better than when I bought it.
Thanks again for all the suggestions.Comment
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Re: '84 injector not delivering fuel
GREAT, I didnt have a diagram here, so I didnt realize that there were two fuses, like the later models.Comment
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