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Discussion Starter · #1 ·
Just got back from a 3mile bike push home. Bike cut out going down the motorway doing about 90. Engine just stopped. Dash lights all stayed on no fault codes etc...Fuel pump primes as normal and i can feel pressure goin into the rail.
Nice strong spark on all 4 but when i remvoed the airbox and tried starting i can see there is no fuel bein squirted in. Everything else works fine. The bike did start intermittently for about 2 mins before stopping so obv a short somewhere or a fault. My questions is What governs the injectors opening and closing and is there a wayto test the related components? Im pretty good at electronics i just wanna know where to start. Is there a relay for the injectors? Should there be a +12v at each injector and the other wire is the switch? Any help greatly appricatied.
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Injectors are ground controlled circuits.

You will be unable to test with a simple volt meter. You will need an oscilloscope.

Injectors fire because the ecu completes the ground side of the circuit. When this happens, the injectors squirt the good stuff. A volt meter will not register voltage changes fast enough to tell if they are firing or not. Shy of an O scope, You can only guess if it is in the injectors or in the injector circuits, or worse in the ecu.

My blind response would be to check all grounds.

An injector is like an ignition coil. A coil within an injector, when the circuit is completed, lifts a tiny needle from its seat allowing fuel pressure to flow into the cylinder.

O-scopes are not cheap, and takes a bit to understand wtf it is even telling you with it's sign waves.
 

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Just got back from a 3mile bike push home. Bike cut out going down the motorway doing about 90. Engine just stopped. Dash lights all stayed on no fault codes etc...Fuel pump primes as normal and i can feel pressure goin into the rail.
Nice strong spark on all 4 but when i remvoed the airbox and tried starting i can see there is no fuel bein squirted in. Everything else works fine. The bike did start intermittently for about 2 mins before stopping so obv a short somewhere or a fault. My questions is What governs the injectors opening and closing and is there a wayto test the related components? Im pretty good at electronics i just wanna know where to start. Is there a relay for the injectors? Should there be a +12v at each injector and the other wire is the switch? Any help greatly appricatied.
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Do you have a Power Commander?
If it's not throwing any codes it's more likely an electrical glitch outside of the injection system, kill switches perhaps.
 

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Discussion Starter · #4 ·
No i dont have a power commander i got rid of it a while back as it was causing problems. What sensors and switches would cause the injectors not to operate. Im thinking crank sensor, cam sensors or tilt switch. Although im not sure which circuits they disable.
 

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No i dont have a power commander i got rid of it a while back as it was causing problems. What sensors and switches would cause the injectors not to operate. Im thinking crank sensor, cam sensors or tilt switch. Although im not sure which circuits they disable.

If any of the sensors weren't working you would expect to have MIL codes flashing. Since you don't, I would start elsewhere first.
 

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Discussion Starter · #6 ·
If any of the sensors weren't working you would expect to have MIL codes flashing. Since you don't, I would start elsewhere first.
Can u point me in the right direction then bladeracer u seem to know your stuff can you be a little more specific? Would a faulty ecm cause intermittent injector failure like this? Or perhaps the alarm system? I thought alarms isolate the starrting or ignition system, not the injectors themselves
 

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Can u point me in the right direction then bladeracer u seem to know your stuff can you be a little more specific? Would a faulty ecm cause intermittent injector failure like this? Or perhaps the alarm system? I thought alarms isolate the starrting or ignition system, not the injectors themselves

Certainly, immobilisers are a prime suspect but if the fuel pump is running I doubt it'd be the immobilser, HISS, BAS and such. Maybe the kill switch itself is bad?
Without any MIL it's unlikely to be a problem within the injection system as I said, it's more likely an open circuit elsewhere, or the ECU is seeing a situation that is prevent it from triggering the injectors. You could try putting a light on the injectors themselves to see if they are actually getting signals to fire but I think it's extremely unlikely all four would fail at the same time.
Otherwise I think I'd be going through the harness unplugging, cleaning and greasing all the connectors to ensure you have good connections throughout.
 

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Oh, the earth block inside the harness is probably worth checking as they are known to corrode and fail.
 

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No i dont have a power commander i got rid of it a while back as it was causing problems. What sensors and switches would cause the injectors not to operate. Im thinking crank sensor, cam sensors or tilt switch. Although im not sure which circuits they disable.
what did the problem end up being I have same thing goin on with mine and can’t figure it out
 

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Just a thought here about testing for injector function. Injectors can be tested for function by applying power, there are injector cleaners designed for motorcycles that actuate the injector so you can soot cleaner through them, I believe Motion Pro sells a variety of models, not sure if they have one for your bike.
Second point, I use to work at a car shop and we used "Noid Lights" to test for signals at the injector. A Noid light is basically an LED in a clear case with leads designed to connect to the injector connector.
Third, my CBR 929 has a PGM-FI test process. The harness has a test mode that causes the PGM light to flash if there is an issue, I found it in the service manual under the fuel system section. I have attached my copy of the fuel system section of the manual for a 200-2001 CBR-929RR. Perhaps this will help.
 

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