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Q Why has my trusty FZR400RR packed up?
I have an official UK 1992 Yamaha FZR400RR which was my road bike in the 90s and then a track bike for the last 15 years. The engine is completely standard and up until six months ago started and ran with no issues. Now, when I turn the ignition on, it primes the pump and fills the carbs, starts after a couple of turns and runs fantastically until the carbs empty (around a mile of riding) then runs out of fuel. I have changed the fuel filter, pump, relay, wiring and checked the float chambers are free of debris.
Stuart Murray, email
Answered by Charles Marvell, Flitwick Motorcycles If this is a stock RR then the fuel pump is powered from the relay via the blue/black wire (the black wire is to earth). The relay is switched via the ECU using this blue/black wire so try earthing it; if the pump now runs, it sounds like an ECU issue, if not the next step is to check for power at the relay, but I’d guess this is good, as the pump primes. My thoughts would be a faulty ECU not recognising the engine is cranking and supplying an earth to the relay. Bearing in mind this is a 24-year-old bike, poor condition wiring connectors could also be a factor. There are quite a few of these ex-race bikes appearing lately, masquerading as ‘original’. Most of them are horror stories. We’ve got one here at the moment; the carbs were assembled with silicone, which dissolves in petrol and one of the pilot jets was missing all together. It was sold to the bloke as a minter.