Fuel injector

Cyclistbruce

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Have finally rebuilt my GS after several months. But, it doesn't start. Turns over ok, good spark from new plugs. Fuel pumped down to injectors.

I've taken injectors out and one of them seems to only be spraying intermittently, when it first turns over and then it feels like it's pumping but no fuel spray onto paper towel.

I should mention that the fuel has been sat in tank since March...
 
I know a lot of folk don't like doing it but….

The easiest way to confirm if its faulty.

Quickstart sprayed into the induction whilst the engine is spinning.
If everything else is ok then she'll start on the quickstart for as long as you spray.

If it doesn't run then its not the injector.

Fuel that old shouldn't be a problem.
 
It did turnover with quick start....

How do I check for the pulse, it switches the ground right? I seem to have a live feed on one of the terminals...
 
It did turnover with quick start....

How do I check for the pulse, it switches the ground right? I seem to have a live feed on one of the terminals...
The majority of Injector systems are NPN switched. That is the injectors have 12v at them permanently once the starter has been activated and the engine is turning. the 0v is switched on and off to pulse the injectors.
Myke
 
It might be worth taking the plugs off your injectors and make sure you can see the two electrical contacts clearly.

There have been occasions where one of the electrical contacts has pushed back in the plug housing giving poor or intermittent connection to the injector.

:nenau
 
The injectors will run intermittantly ;) it stops you pumping unburnt fuel into the cat

Unless BM have there own version of things

the system is missing a value from another sensor to show combustion is happening, and to keep the injectors runing

In this case i would say egt or Lambda

Now if you have a misfire - the injectors run and then do pump unburnt fuel into the cat ;)
 
Right, have cleaned the injectors with brake cleaner, and checked they open ok. Put new fuel into the tank (still a bit of old in there, but should be OK). Put it back together, and nothing.

So - injectors are are now running - spraying when taken off and can hear them "clicking" with the long screwdriver stephoscope against the injector thingy. Plugs are sparking. It starts (briefly) with Easystart spray - but dies straight away.

Am at a loss.... but would the lambada sensor stop it from starting, I thought this would make it misfire?

Only other weird thing, this time around when I took off the left hand injector I accidentally pulled the body from the fuel line. Normally I get a squirt of fuel at pressure (ignition off obsviously) and then it stop. This time it just flows continuously. Shouldn't fuel only be coming through to the injector bodies when the pump is working?!?!

This bike is getting closer to the breakers yard.
 
Sounds to me like you have no fuel pressure from your description above.
Maybe split internal pipe?

Do you mean inside the tank? I am getting fuel down to injectors and it seems to be at pressure when I take the injector body off the supply line....
 
Ok back to basics (not teaching you to suck eggs btw)

Suck, Squeeze, Bang, Blow

Suck, have you got fuel & air entering the combustion chamber?

Squeeze, have you got correct compression

Bang, have you got ignition

Blow, have you got exhaust from the combustion chambers?

Running on easistart (startyabastid) would indicate no fuel, although it can have a negative effect in that engines get addicted to the lower combustion ratio, and become hard to run normally! (Although i would think it highly unlikly in this case )

When you turn on the ignition, does the fuel pump (run) prime and pressurise the system?

Battery fully charged 12.3V - 12.8V

Airfilter and associated piping not blocked, and inlets to the throttle bodys not restricted ( butterflys opening ok, not stuck open / shut)

Fuel at the injectors, and injector spray ok and at correct pressure.

Compression within acceptable limits

All spark plugs gaps correct and plugs sparking with a good blueish spark when tested?

Thats the simple stuff...

OK ignition sytems and cycles have made huge improvements / changes in recent years

The basic way to describe a generic ignition cycle is /was

Ignition on -

ECU energises and checks input values from relevant sensors

Cam / crank used to work out TDC and engine speed (needed for 3D ignition map)

Map / MAf - used to work out airflow into the engine, enables ECU to alter air / fuel ratio to maintain 14:1 ratio and Lambda ratio .97 - 1.03 (ish)

Lamda - measures fuel air ratio in exhaust and tells ecu its results so fuel air ratio can be adjusted - contrary to popular belief not all fuel gets burnt in the combustion chamber it ends up going out the back

Oil temp / water temp / Air temp all give the ECU inputs before ignition has taken place

Once all of that lot has fed its data back to the ECU and its all in spec (milliseconds)

The fuel pump will energise and pressurise the fuel system. - again an ok flag will be sent back to the ECU

ECU will have set the ignition map based on the data recieved earlier to give the

optimum fuel air ratio for the engine to start based on its current data (cold engine)

Pressing the starter the ECU looks for signals from

Injectors - Are they pumping fuel at the right time

MAf / MAP how much air is entering the combustion chamber

Crank & cam sensor - to provide spark at the correct times before TDC

Lambda - what is the ratio of unburnt fuel in the exhaust gasses

If ignition occurs, the ecu then looks for signals from the throttle position sensor /

or butterflys on the throttle body

Cam and crank sensor to work out RPM and ignition timing map

Lambda to work out fuel ratio

Oil / water temp to lean the mixture off as the engine warms up .

if all of the above are ok then the engine should be running normally.

In the old days you could have a misfire, and pump raw fuel through one or more

cylinders, and contaminate the cat and give the Lambda probe a real headache ;)

Modern systems can detect lack of ignition, or ignition problems and shut down

relevant injectors etc to protect other systems down stream.

From what you describe, you have air, ignition and compression, but the fuel isnt

being injected, or injected at the right time.

That would point to cam or crank sensor - you could try turning the ignition on, and

unplugging the cam and or crank sensor then plugging it back in. and then trying

to start the engine... often a failing cam or crank sensor will not send a signal to

the ecu, but a bit of voltage kick can send he required signal and the engine will

start. I had a cam sensor that would prevent starting, but unplugging and

replugging it in and the engine would start everytime.

Hope this helps
 
Thanks, brilliant reply, it must be a fuel supply problem, I haven't checked the HES, but assume that its fine as have spark and fuel...

I'm going to see if I could find a fuel pressure gauge dohicky and check that.

Also, randomly since I have put the tank back on it reading as full on the display, despite only having a few litres in it!

Anyway, off to test ride a Super T now!
 
It's started!! Clutch replaced, gear box overhauled, coil replaced, injectors fixed.

Sooo, why is it not idling below 3000.... Have adjusted grub screws on injector bodies, cables are running free. As I'm waiting for a new gear position sensor I don't have the rear drive on (thought this would be a safer way to test going through the gears also, rather than bike shooting through shed walk into neighbors garden!). But this shouldn't make a difference to idle right?
 
throttle cables seated correctly in the bodies?

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