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1Back to top Go down    Fuel Injectors on Sun Jul 01, 2018 4:15 pm

@kustom_moto

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Guys, I am not getting fuel from the injectors when the start button is pressed. I have read for a good hour previous posts about this.

One thing I picked out is that if you disconnect the injector electrical plug and put a small 5w bulb wire into the positive of the harness and the negative to the battery then you can test if the plug is getting power (bulb should light when start button pressed). Am I correct in thinking this is a sound test because The bulb is lighting but no spray. I have also tested 1 injector to a battery and it clicks and sprays when I force cleaner through it.

Could it be my Hall Sensor? Could it be these 30 year old injectors maybe are shot? I was starting to look for maybe the 4 hole type. Any help much appreciated, cheers

Paul


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1988 K100 LT
1984 K100 RS

Instagram K100 Build follow me at: @kustom_moto
    

2Back to top Go down    Re: Fuel Injectors on Sun Jul 01, 2018 5:42 pm

nino


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Hi Paul,

in my case it was faulty temperature sensor. Engine reacts but only with a lot carb cleaner. No gasoline on injectors at all. Engine normally started after I changed temperature sensor.
Problem was position of sensor deep inside. i hope you know where to look.
Regards

    

3Back to top Go down    Re: Fuel Injectors on Sun Jul 01, 2018 6:10 pm

robmack

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If you're going to try the test light, you have to use a 12V LED, not a regular incandescent bulb. The reason is the pulses to the injectors are very short and an incandescent bulb is too slow to respond. Furthermore, you'll want to test on the grounding side of the injector, not the supply side of the injector. That means connect the test LED between any of the Yellow/Grey wires and ground (ie. anode of the LED to Yellow/Grey, cathode to ground). Don't hookup to the Green/Red wires because you will always see 12V on those wires. The way the injectors work is that the ECU completes the grounding path when the ICU tells it to fire. So, the LED will flash OFF briefly when the injectors fires. Remember, all injectors fire at the same time.

Another test is to use a long handled screwdriver like a stethoscope to listen to the injectors. Place the tip of the screwdriver against the injector you want to test and press the handle of the screwdriver against your ear. Turn the engine over. You should hear distinct clicking sounds through the screwdriver.

You may have a faulty HES but then you wouldn't get spark either. Are you getting spark at the plugs?


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Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
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4Back to top Go down    Re: Fuel Injectors on Sun Jul 01, 2018 8:54 pm

RicK G

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You can feel the click of the injector. I just put the tip of one finger on the body of the injector, it is very distinctive.


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"Every normal man must be tempted, at times, to spit upon his hands, hoist the black flag, and begin slitting throats." from Mencken's 1919 Prejudices

Bikes 1993 K1100 LT, 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 for now
    

5Back to top Go down    Re: Fuel Injectors on Mon Jul 02, 2018 12:30 am

club_c

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I also ran into this issue with my 85 and the injectors had sealed shut with gas varnish and no amount of effort to clear them would get them working. Replaced them with a good used set of injectors from a Ford Ranger of all things and it flashed straight up.



Last edited by club_c on Tue Jul 03, 2018 1:43 pm; edited 1 time in total


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"There's never enough time to do it right, but there's always time to do it over."

1988 K100RS SE VIN 01477554
    

6Back to top Go down    Re: Fuel Injectors on Mon Jul 02, 2018 3:34 am

@kustom_moto

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Robert, yes I have a strong spark.

I will try with LED light later today.

On the bench the injectors rigged up to a 12v battery, I am able to squirt carb cleaner through so these seem ok.....


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1988 K100 LT
1984 K100 RS

Instagram K100 Build follow me at: @kustom_moto
    

7Back to top Go down    Re: Fuel Injectors on Mon Jul 02, 2018 4:54 pm

@kustom_moto

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**update**

I have found an old LED rear motorcycle light which I presume is 12v. I have inserted the red wire into the grey/yellow end of the harness and the black wire onto the battery negative, turned the bike over but no light. If I switch the LED red wire into the green/red end of the harness it blinks really fast but reading below that is not the correct way around so doesn't count! Am I testing correctly? What would cause there to not be power to the injectors??

I am struggling to hear the clicks through the noise of the engine turning. Regarding the injectors on further investigation 1 worked on the bench, 2 were blocked and 1 is dead. I have now cleaned all 3 and they are spraying and have taken a forth from the new bike, tested and now have a set of 4 all working.


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1988 K100 LT
1984 K100 RS

Instagram K100 Build follow me at: @kustom_moto
    

8Back to top Go down    Re: Fuel Injectors on Mon Jul 02, 2018 6:03 pm

robmack

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Hmm, you should have gotten a reading on the yellow/grey wires. Maybe I was wrong about the setup and the LED needs the 16 Ohms resistance of the injector to register a voltage drop and therefore activity on the LED. Ok, so if you're seeing the LED blink in synchronization with the engine speed, then you can assume much about the state of the ignition system. There are no problems with the HES because you have both spark and injector pulses. You've confirmed that you have renovated the injectors which appeared to have been in poor shape. I'd venture to say that the ICU and ECU are working as expected although I won't stake my life on that. Smile I'd think you should reinstall the injectors and try to start it again.


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Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

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