Running without TPS?

[filbert]

I lent my 99 Kat to a friend and he was on the interstate when the engine died on him and left him without power during rush hour... Luckily he managed to get over to the shoulder and a nice guy with an empty trailer stopped and helped him tow the bike back.

We took off the fairing and discovered that the wire harness for the Throttle Position Sensor had come loose and this apparently caused the problem. It seems to be running fine again with it reconnected.

1st question - has anyone had an issue with the TPS plug coming loose? Do you think this was a fluke or do they tend to do this every once in a while?

2nd question - based on other posts on this forum, the TPS is primarily used to adjust timing and supposedly increase power or efficiency or something along those lines. Someone said that the engine should still run even if the TPS is disconnected. Is this true? Does the fact that the engine dies within 30 seconds of disconnecting the TPS indicate some other tuning issue?

[Kreylyn]

I lent my 99 Kat to a friend and he was on the interstate when the engine died on him and left him without power during rush hour... Luckily he managed to get over to the shoulder and a nice guy with an empty trailer stopped and helped him tow the bike back.

We took off the fairing and discovered that the wire harness for the Throttle Position Sensor had come loose and this apparently caused the problem. It seems to be running fine again with it reconnected.

1st question - has anyone had an issue with the TPS plug coming loose? Do you think this was a fluke or do they tend to do this every once in a while?

2nd question - based on other posts on this forum, the TPS is primarily used to adjust timing and supposedly increase power or efficiency or something along those lines. Someone said that the engine should still run even if the TPS is disconnected. Is this true? Does the fact that the engine dies within 30 seconds of disconnecting the TPS indicate some other tuning issue?

Yeah, something else is wrong... The TPS normally makes a very fine adjustment to the preset ignition curve from the CDI for 1st and 2nd gear only. With no input from it, there should be no issue with any changes, and it would use the default ignition curve.

I've done multiple engine and carb swaps and such... have had no issues with running with out the tps.

Are you absolutely sure you have tested this conclusion that unplugging the TPS will cause the bike to stop, and it was just something you noticed after the issue started?

Krey

[filbert]

Are you absolutely sure you have tested this conclusion that unplugging the TPS will cause the bike to stop, and it was just something you noticed after the issue started?

Krey

This actually happened a week ago. My friend tried to start it and it ran ok for about a mile before actually stranding him. He tried to start it again on a couple different occasions but no luck.

When I finally got a chance to stop by with some tools today, we tried starting it. No luck. After we remove the fairing and discovered the disconnected plug, we reconnected it and it started right up.

We then noticed the harness was loose and it vibrated off again. It started to run rough and in 20-30 seconds it died. When we reconnected it again (this time making sure it was fully seated and clicked into place) it started right up again.