Yamaha YBR125 wont start

[digifixuk]

Hi everybody, my sons YBR125 had a replacement fuel tank and Pump fitted after his old tank started leaking and it was full of rust,since then the bike turns over but dosent fire, there is fuel coming out from the pump, there is a spark from the plug but no fuel coming out of the injector we have had the injector ultrasonically cleaned and we have seen it spraying in the garage,if you put some fuel in the cylinder where the injector fits the engine fires and runs for a second or 2 has anyone got a clue what i should try next? thanks in advance Bob

[Easy-X]

So let me get this straight:

If you remove the injector, point it in some safe direction and try and turn over the engine fuel squirts out?

If you remove the spark plug and try and turn it over you get a good, visible spark?

Rather than removing the injector have you tried removing the air filter and squirting "Easy Start" in there?

If you're getting some fuel and some spark and some air I'd expect it to at least a splutter...
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[WD Forte]

year? mileage?

Does the yellow engine light flash after switch on?
If the ecu detects a fault, it will give an error code in a 2 number sequence
eg 1-9 for example

Don't use Easy start!, that junk wont fix anything.
Find fault, fix fault

Open check and clean ALL connectors behind the injector body and under
the LH side panel
Check terminals for corrosion, unlatched pins that may have been pushed out of position when you swapped tanks and fuel lines.
Check the crank position sensor resistance while yer at it
It has a 2 way connector with red and white wires
____________________
bikers smell of wee

[Easy-X]

Easy Start isn't a "fix" it's a diagnostic tool
____________________
Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Robby]

Just to be clear, the injector is working when it isn't fixed in place on the bike. Can you give some more info here:
- is it still connected up to the bike wiring and fuel supply, just pointing away from the bike?
- is it producing a fine mist of petrol, or a pathetic dribble?

I'm thinking of two possibilities:
1. The injector is working, but there is very little fuel pressure or the line is full of air that needs bleeding out. Bleeding out the air can be done by just cranking the engine, as the injector operates it will squeeze out whatever is in the line. If the pressure is down, I would be looking again at the fuel pump and making sure it works, has a good fuel supply, and isn't full of air. Not sure if these use a one or two line fuel system.

2. Electrical. Either the wiring is dodgy and is shorting out when the injector is installed - giving it a wiggle will help diagnose where the problem is, if you wiggle it and it runs then you've found the bad wire.
Otherwise it could be the injector shorting out when installed on the bike. This shouldn't happen, but could be possibly in some circumstance with really knackered wiring.

[digifixuk]

[Easy-X]

This might help:

https://ybr125owner.blogspot.com/2014/06/yamaha-ybr-125-fuel-injection-system-fi.html

TBH I'm having a hard job working it out from the YBR wiring diagram but if your injector is switched earth then yes you would see +12V power but the injector might not be activated at the appropriate time by the ECU.

Two likely possibilities: low fuel pump pressure (clogged with crap from the old rusty tank maybe?) or a totally co-incidental fault like a safety cut out (e.g. side stand switch knackered, that sort of thing.)
____________________
Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[digifixuk]

[Islander]