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Injectors not firing

KjmMarine

New member
Hello, I am working on a 2002 BF200a that wont start, I have spark and compression, I have also verified that fuel is getting to the Injector rail. Ive pulled injectors and am going to replace anyway since they werent in great shape and 2/6 ohm’d out to be bad anyway. I donot believe any of them are firing, spark plugs come out dry. How do i test to see if they are getting signal/power to fire?
 
Hi,

Well, the pros would hook up an oscilloscope to check injectors but most of us don't own one. Know anyone that might?

Another way is simply "back probing" an injector at the connector with a DMM set on millivolts to see if there's a rapidly flashing "reading". This won't tell you anything more than if there's something happening and, it's not always a reliable test. It's also easy to damage the connection if you aren't very careful doing the probing but that goes for using an Oscope too. Gently does it!

I've had pretty good luck finding injector pulse using "noid" lights. You can place a noid light over an injector wire and it will light due to conductance from the current flowing much like an amp clamp style current tester. It's nice because it's "non invasive".
But.....
noid lights sometimes don't work either unless you have the specific one needed for the system you're checking.

Having said that though, the cheap set of noids I bought at Harbor Freight years ago work on most cars I check if they're 2009 or older. You just have to try them one at a time.

There's other methods, including Dr H but, again, it's something most don't have.

Good luck.
 
Hi,

Well, the pros would hook up an oscilloscope to check injectors but most of us don't own one. Know anyone that might?

Another way is simply "back probing" an injector at the connector with a DMM set on millivolts to see if there's a rapidly flashing "reading". This won't tell you anything more than if there's something happening and, it's not always a reliable test. It's also easy to damage the connection if you aren't very careful doing the probing but that goes for using an Oscope too. Gently does it!

I've had pretty good luck finding injector pulse using "noid" lights. You can place a noid light over an injector wire and it will light due to conductance from the current flowing much like an amp clamp style current tester. It's nice because it's "non invasive".
But.....
noid lights sometimes don't work either unless you have the specific one needed for the system you're checking.

Having said that though, the cheap set of noids I bought at Harbor Freight years ago work on most cars I check if they're 2009 or older. You just have to try them one at a time.

There's other methods, including Dr H but, again, it's something most don't have.

Good luck.
So i used noid lights, 5/6 injectors are firing, i have continuity for both wires on the daulty injector from harness to injector, dont have a way to see if the ecm is putting out a signal. My multimeter isnt that advanced. But since i have continuity i think its pretty safe to assume the ecm isnt telling it to fire
 
Have you tried checking the resistance of the injector coil?
It should match the resistance of the ones that work if you don't have the exact specifications. Typically 2 or more ohms but each system is different.

Excuse my lack of knowledge on this system but how are the injectors being powered?

I mean, do all of them have voltage going to them?

A typical system will have voltage....usually 12 volts.... going to the injector and the computer switches the ground. So, if the injector that's not firing has voltage going to it, then it's either faulty or the computer isn't grounding it either because the driver is bad or the wire from injector to ECM is open

If the injector is being powered, you can unplug the connector at the computer and see if that voltage is present going into the computer. If not, you have a bad wire but if there's voltage then it's likely the driver in the computer has failed.

One VERY important thing you need to be aware of if you decide to replace the computer, is that sometimes it's voltage spikes from a faulty injector coil that will destroy the injector driver in the computer. If that happens and you don't replace the injector then your new computer might also be damaged.
And, if something like that is happening then you need to consider that other injectors could be failing in the same way.

Sorry for the dark message but you need all the information you can get before spending the big amount of money a new ECM costs.

Good luck.
 
Have you tried checking the resistance of the injector coil?
It should match the resistance of the ones that work if you don't have the exact specifications. Typically 2 or more ohms but each system is different.

Excuse my lack of knowledge on this system but how are the injectors being powered?

I mean, do all of them have voltage going to them?

A typical system will have voltage....usually 12 volts.... going to the injector and the computer switches the ground. So, if the injector that's not firing has voltage going to it, then it's either faulty or the computer isn't grounding it either because the driver is bad or the wire from injector to ECM is open

If the injector is being powered, you can unplug the connector at the computer and see if that voltage is present going into the computer. If not, you have a bad wire but if there's voltage then it's likely the driver in the computer has failed.

One VERY important thing you need to be aware of if you decide to replace the computer, is that sometimes it's voltage spikes from a faulty injector coil that will destroy the injector driver in the computer. If that happens and you don't replace the injector then your new computer might also be damaged.
And, if something like that is happening then you need to consider that other injectors could be failing in the same way.

Sorry for the dark message but you need all the information you can get before spending the big amount of money a new ECM costs.

Good luck.
Everything seems to be checking out on the fuel side minus the one injector not firing. I replaced all 6 injectors, verified spark again in all 6 cylinders..
Went to fire her up and still no start, wont even fire on starter fluid. Im thinking the starter motor is weak and on its way out.
 
Well, if it won't fire on start fluid then it's either not got the good spark that you think it has or something else is way out of whack like valve timing.

Although, yes, if you can't spin the engine fast enough (150 rpm or so) with the starter, then you could be correct.

But an engine that's out of time won't crank over efficiently either and might fight against the starter.
Does it crank in a sort of "fast then slow" rhythm? If so, that's a classic symptom of being out of time and you should look in to that.

Be very careful using start fluid (ether) as it will damage the engine if used incorrectly.

Good luck.
 
Hello, I am working on a 2002 BF200a that wont start, I have spark and compression, I have also verified that fuel is getting to the Injector rail. Ive pulled injectors and am going to replace anyway since they werent in great shape and 2/6 ohm’d out to be bad anyway. I donot believe any of them are firing, spark plugs come out dry. How do i test to see if they are getting signal/power to fire?
Check out/call "Fuelinjectorman.com" down in southwest Florida. If still in business he's a great resource. He cleaned 4 injectors from my Yamaha 150 and the engine ran perfectly. Try calling him.
 
Well, if it won't fire on start fluid then it's either not got the good spark that you think it has or something else is way out of whack like valve timing.

Although, yes, if you can't spin the engine fast enough (150 rpm or so) with the starter, then you could be correct.

But an engine that's out of time won't crank over efficiently either and might fight against the starter.
Does it crank in a sort of "fast then slow" rhythm? If so, that's a classic symptom of being out of time and you should look in to that.

Be very careful using start fluid (ether) as it will damage the engine if used incorrectly.

Good luck.
Is checking timing something i can do with basic tools? Or do i beed specialty tools
 
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