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4Rt Only Runs With Fuel Pump Disconnected!


thall1
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right here goes!..... ive had numerous starting issues with this bike now I have another. Bike would not start  at the weekend. (again!) After much investigation and testing listed below the bike will only run if the bike is kicked once to prime the injector and then the tank pump disconnected...it will then start (after two kicks) and run for a few seconds on the fuel sat in the injector. If I re-connect the pump it floods and its just a wet plug...not even a hint of starting? if I connect the pump whilst its running the engine dies.

 

 

all electrical tests as per manual ok.

12v output at the plug under tank.

good earths at yellow plug and to and from the ECU.

new plug.

new HT lead and plug cap (used a new  car HT lead).

fuel line disconnected and plenty of fuel being pumped whilst kicking over.

Electrical pulse to the injector tested with a test lamp - regular pulses seen at lamp

injector tested on a 12v battery....

injector tested whilst connected to the pump.....good spray of fuel and it does not appear to be leaking fuel from the injector with the injector closed but whilst still under fuel pressure.

 

still wondering if the injector is leaking fuel into the barrel? hence the flooding or the spark seen outside the bike with the tank pump connected is not good enough once its in the bike and is washed out by the fuel? 

 

Where does the ECU get a signal from to pulse the injector at the correct time/stroke of the engine?

 

Thoughts please?!

 

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To me sounds like all is working but ecu is saying don't run.

Check throttle free play, bank angle sensor, kill button, clean throttle body internals. Makes sure bypass/tick over port is clean on throttle body. Check air filter and air box.

Good luck

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Where does the ECU get a signal from to pulse the injector at the correct time/stroke of the engine?

 

All timing would be based off crankshaft sensor I suppose, as I have never worked on t Mont.

 

 

If you suspect a stuck open injector causing flooding it may be possible to attach the hose end of a handheld vacume pump to the nozzle end of the injector. It should hold vacume if the injector is closing as it should.

 

M2C

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To check for a stuck-open injector, you could also just remove the tank / injector assembly from the bike (leaving fuel line and return line connected), position so fuel tank is normal (with some fuel in it) and injector is over something to catch fuel, and connect a battery to the fuel pump 2P black connector. For checking stuck injector, I don't believe you'd need to have the injector connected or pressure regulator vacuum line on. So it could be done away from the bike on a bench.

 

It sounds like you may have already done something similar in the first post.

 

If you know someone with the PGM/FI programming tool, it has some primitive diagnostics. Look in the manual chapter 6 for information.

 

Good luck, hope you find the problem.

 

Edited by sportsawyer
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ECU gets timing signal from crankshaft sensor and also gets a signal from throttle position sensor plus a few others.

 

Is the throttle returning to it's stop on the throttle body, check throttle cable is seated correctly and not popped out at either end.

 

Try winding air screw in or out to see if it makes a difference - only by half a turn either way though.

 

Have you tried disconnecting injector with pump connected then trying to start, then pull plug to see if it's wet.

 

See attached PDF of system it's for a 260rt 

 

PGM Montesa.pdf

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You could have a potential short circuit in your fuel pump or in the wiring harness.

 

Remember that the red power cable that feeds the fuel pump also deliver power to the the other components on the bike.

But, if the bike runs without fuel pump electrical connected - would I suspect the fuel pump to be faulty.

Can you hear or feel if the fuel pump are running !!!  


Regards
Hond Freak

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Either the injector is stuck open or the ECU is opening the injector more than it should.Wonder if theTPS is faulty and informing the ECU that the throttle is wide open when it's not and over fuelling it.Often these sort of problems are caused by poor connections in the plug together connectors.Id part them all and zap them with contact cleaner.Good luck

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I am wondering if you have been able to turn up the idel/tick over speed and see if that helps yet? 

 

Any other information you have been able to figure out?  any changes or other data that might help based on some of the other comments?

Edited by jonnyc21
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the idle is set ok. Turning it up or down makes no difference....the engine only runs with the fuel

line disconnected on the fuel in the injector...I have after many very short engine runs managed to

get it going with the pump connected but it appears to be running rich. Once the engine is warm it

will start without much problem but when its left to get cold overnight it wont start. If the bike is kicked over without the fuel line connected but the tank electrical plug made then the pump works.

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