5th gen electrical gremlin???

ok bike is a 98 vfr800, any ideas on the next step from here?

The bike was running ok while riding to work in the cool morning air then would start missing like a dropped plug / loose ignition wire on the way home in the warm afternoon air. It would run ok for about 50km then start misbehaving. Ran like that for while. Then stopped completely in the middle of nowhere. I eventually managed to disturb enough wiring and various other bits to get it home. Where it died half way up my driveway and hasn't gone since.

trouble shooting done so far,
new plugs, all 4 were coked up. unlikely to have dropped all at once. Put new ones in anyway.
changed the reg rectifier
checked for obvious wiring issues loose plugs, continuity on the kill switch, all earths ok. checked everything from the ecm to sensors for continuity, all ok. No obvious shorts.
ecm has no 5v out, has 12v in to it but no 5V out. changed ecm still no joy
changed battery, rules out intermittent internal problem with it.
resistances on all sensors are within the specs in the shop manual.
air filter is clean
fuel system has plenty of flow, so unlikely a clogged filter or dissolved impeller.

bike will turnover and fire once with the throttle shut, then dies again. Won't fire with throttle open. ecm is flashing codes 1, 7, 8 & 9 which is no 5v out of ecm.

any ideas what to check next? thanks

 

Do you have a list of the codes and have you checked them?

1 = Loose or poor contact on MAP sensor; Bad Map Sensor; Open or Short Circuit in MAP sensor

7 = Same as #1, except ECT sensor

8 = Same as #1, except TP sensor

9 = Same as #1, except IAT sensor

According to the manual, your engine "should" operate normally with any of these EXCEPT for #8. The manual clearly states there will be engine/throttle issues.

When operating normally, the standard is 4.75V to 5.25V.

Based on your comments above, maybe its the TP??

Good luck.

 

Turns out the real cause of the problem was previous owner mistaking ego for ability.

Reg/rec was moved to the horn location, didn't think about where they ran the wires when they did it, rubbed through in a few spots over time. Connector onto reg/rec wasn't waterproof or plugged in properly. Also put the connector from the main harness to the throttle body harness around the main loom instead of straight out which pulled/rubbed the TPS power and signal wires together in the loom which shorted out the 5v. So after picking the main harness apart, rerunning some wires, changing & moving the reg/rec back to stock location & putting a new battery in it's going again.