Join Date: Sep 2008
Location: Honolulu, HI, USA
I agree the pump seems to be your present problem, but probably not the only one, so fix the pump and report. You also need to know that after long storage, there's good gas in there.
A long-stored engine could have rodent infestation that blocks airflow, or some little booger gnawed a great horrible hole in the intake tract. Since the bikes don't use manifold vacuum as an ECU input, it's unclear whether an intake leak would cause a starting problem. Running issue, probably, since more air would enter than indicated by the throttle position sensor, and the bike would stall lean.
I'm may be a little out of my depth but: an engine starts on a preset rich mixture and is then controlled by the ECU according to information received from sensors. That it may not idle could be caused by several things.
Verify adequate fuel delivery (pressure and volume) but since there is no fuel filter there should be no restrictions downstream of a properly working (on/off) pump. The pump is not "controlled" by the ECU, other than on/off.
The fuel rail and injectors should see constant pressure, monitored by the fuel pressure sensor on the fuel rail. The sensor could be off, telling the ECU that the pressure was high (mixture is rich) so the ECU compensates by shortening the injection pulse width/duration, resulting in lean stall. If you have a GS-911 it will tell you the fuel pressure as reported by the sensor, as if the pressure sensor is correct, which latter may not be. My fuel pressure sensor showed a constant incorrect value at about 42 psi (converted from whatever the GS-911 readout was, and they don't tell you the units, damn their eyes).
OR, as I found to my expensive dismay, the fuel pressure sensor could report low, resulting in longer injector pulses and a very rich/barely running engine. This does not seem to be your problem, I only mention it to illustrate that when the sensor takes a shit, the bike may run very rich if at all.
BMW cars with slowly failing crank sensors (they report rpm to ECU) show resistance values out of spec, but I don't know the bike sensor resistance spec. Perhaps someone will chime in. It might be the same or not much different from the car sensor values, I dunno.
Please post the diagnostic approach, results and solution for your bike. There's a real dearth of tech info how the bike is supposed to run, and each found solution can enrich the rest of us.
Last edited by Honolulu; Jan 16th, 2020 at 7:20 pm.