Surging and bucking is back

Nibbio Posts : 634 Join date : 2013-12-23

2013 Black Devil,Title tells it, second ride of the spring season no problem on the way out, 80+mph without a hiccup. After a 15 minute stop horrible, surging and bucking bike stalled at every stop unless revs applied. Fuel economy shows 30 mile per gallon average and the tank was down to its last 3/4 of a gallon when the surging started. In the past I thought this was a plug wire problem so I changed the caps to the recommended NGK has anyone else had a similar experience?

Assuming there isn't a dead cat in my intake the problem has to be fuel or spark. How would I go about eliminating one of those two options so I don't end up chasing my tail?

Plugs here:

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Nibbio Posts : 634 Join date : 2013-12-23

I used a pump to suck the last 3/4 gallon of gas out of the tank and put that gas in the mower. Added two gallons of fresh premium gas and R/R the start button/kill switch to dowse it in DeOxit. The bike started and idled but it stumbled a bit past 4500 RPM. After it warmed up the stumble did not reappear. I will take it for a ride after lunch.

I got my answer. Ran fine for 15 minutes and then the worst bucking and surging you can imagine. I limped home and set up in front of the garage with a couple of big fans pointed at the motor. After a few minutes of idling and a bit of revving it bucked and then shut down, no idle. I pulled off the wings and the coils were cool to the touch and had good grounds to the frame. I put the timing gun on left then right plug wires but both coils seemed to be firing normally. Alternator was putting out 4.6 V. Seems like a fueling issue. The exhaust doesn't smell rich so I think it is just periodically starving of fuel.

GRiSO Capo Posts : 10711 Join date : 2013-05-29 Age : 67

Phase sensor? Fuel pump? Relay?

Nibbio Posts : 634 Join date : 2013-12-23

Pete Roper wrote:: Phase sensor? Fuel pump? Relay?

Thanks Pete!

In order of simplicity:

Which relay?

Can I remove/clean the phase sensor?

Let's leave the fuel pump for last...

GRiSO Capo Posts : 10711 Join date : 2013-05-29 Age : 67

Whichever relay controls the ECU most likely. I can never remember offhand.

Phase sensor just needs replacing if it's dodgy, they aren't terrifically expensive and are prone to heat related failures.

Fuel pump is also dirt cheap on the Bay of Fleas.

Nibbio Posts : 634 Join date : 2013-12-23

Pete Roper wrote:: Whichever relay controls the ECU most likely. I can never remember offhand.

I'll treat them to some contact cleaner.

Phase sensor just needs replacing if it's dodgy, they aren't terrifically expensive and are prone to heat related failures.

Hmmm, problems occur after the engine heats up, interesting.

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Fuel pump is also dirt cheap on the Bay of Fleas.

GRiSO Capo Posts : 10711 Join date : 2013-05-29 Age : 67

You can buy an aftermarket one for Fiat/Lancia a fair bit cheaper if you hunt around.

Fra Cristoforo Posts : 828 Join date : 2016-04-14

Make sure you get correct amount of pin connectors as your bike. Three pins
Check depth too.

GRiSO Capo Posts : 10711 Join date : 2013-05-29 Age : 67

I'm visiting my daughter in Wollongong this weekend but when I'm home I'll dig out the part# for the aftermarket one I use.

Nibbio Posts : 634 Join date : 2013-12-23

Thanks Pete. MG has my part in the mail so we will see.

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