Yamaha Thundercat Rev counter gone loopy!

[Johnster]

Hi,

Went out for a blast on my 98 Thundercat yesterday afternoon for a couple of hours but when i was on my way home i noticed the rev counter dropped to 0 Rpm for a coupe of seconds then back to the current rev range. It continued to do this for a good 10 minutes before i pulled into the petrol station and filled the tank up.

I had been running on reserve (Or with the light on if you like) for about 20 miles before this started to happen.

After i'd filled up by the way the problem disapeared?

I have looked in the Haynes manual at the error codes the rev counter produces but going to zero then back to the current speed continually isn't in there!!

Should this be anything to worry about?

Thanks,

John

[skinny]

Could be that you didn't notice it go to 8000rpm or 3000rpm as it go from there to 0 back to proper engine speed. the only rev code that has to do with fuel is as below may be as you were very low on fuel it may just picking up a fault that isn't showing when full. hope this helps.

0....8000rpm....0....actual engine speed.... repeat

Fuel level warning system has an open circuit somewhere. Either the level sender is bad, has a bad ground connection, the connector (small green connector under tank on left side of bike) is disconnected, or the bulb itself is blown.
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oops I did it again....

[Johnster]

Hi,

No, it definatley just went current RPM - 0 - current RPM - 0 - Current RPM... etc...

I have heard about the 4000 and 8000 RPM fault codes but it definatley didnt do these.

Bulb works as the light had been on for some time.

So you think it's the Level sender then?

I'll have a look ans see if i can find any loose wires / connections.

Thanks for your help.

John

[fazza59]

Thundercat rev codes are

Tach readout: 0......3000rpm.......0........actual engine speed...... repeat

Throttle position sensor is disconnected or the reading is outside of the normal band.
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0....8000rpm....0....actual engine speed.... repeat

Fuel level warning system has an open circuit somewhere. Either the level sender is bad, has a bad ground connection, the connector (small green connector under tank on left side of bike) is disconnected, or the bulb itself is blown.

Think it might be the fuel sensor.
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Current - Yamaha R1 - Yamaha XJ600N - Kawasaki GPZ 500S (project? Maybe )
Pics of my bikes

[andys675]

check the block connector going to the clocks, mine was turning purest green inside from the corrosion on the copper contacts

[Pete.]

I agree fuel level sender. It probably has poor contact at the end of it's sweep, which will only show-up at very low fuel levels.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[minemich]

I had similar problem once... My tach started getting a little squirly on me... Would kind of float around, drop to zero.... And never really show the proper RPM. I replaced the tachometer cable, and found that the old one was entirely stripped at the end where it fits into the engine... This may be an issue....

[Johnster]

Thanks for the help, a couple of things for me to look at this week.

It has only happened a couple of times and only when the fuel level is extremley low.

Cheers,

John