Temp gauge starts to rise........ unless

the-elf · Post by **the-elf** » Wed Jul 02, 2008 11:43 am

Have you changed the sender?

LotusSevenMan · Post by **LotusSevenMan** » Wed Jul 02, 2008 5:50 pm

Yes, sender changed too. Same results.
A higher authority reckons that the voltage figures are OK as at idle the Voltage Regulator is doing very little so you get the generator on basically full (low power) ouput. As the revs rise the VR kicks in and gives a nice steady charge to the battery so that area can be assumed to be OK too.

Fuel consumption on these bikes is really dreadful. I must have used a gallon to go nowhere but a paddock stand!!!

Convinced now (90%) that it is a nineteen year old wiring loom problem.
Going to rig it up with a live feed etc from the ignition supply and new earth straight to the gauge etc.
This will prove hopefully that the loom is at fault somewhere.
Geez, I do hope so.
I'm fed up with feeling like the emoticon here

LSM

LotusSevenMan · Post by **LotusSevenMan** » Wed Jul 02, 2008 11:01 pm

I don't believe this now.

Wired in a different sender to another gauge with no loom attachment at all. This was with an independent gauge and an independent battery with just the sender unit wire attached and an earthing (negative from battery) to the chassis.
This hould work eh?
Does it nelly!
Same result as before.
Unreal.
It can't be two duff :- 1) voltage regs 2) batteries 3) sender units 4) gauges 5) totally different loom structures.

kwackman12 · Post by **kwackman12** » Wed Jul 02, 2008 11:53 pm

Have you tried running an earth wire direct from the battery to the engine/sender unit? as you might be getting a voltage/earth drop through a corroded/bad connection? the way to check it is switch your multimeter to volts (dc) connect one lead to the earth side of the battery & the other lead to the engine /sender unit switch the ignition on & the multimeter should read infinity (zero) any voltage registered is the actual voltage "lost" through a bad connection, you can use this method to check all the earth connections through the loom this link might explain it a bit clearer also works on the positive side http://www.engine-light-help.com/voltage-drop.html

LotusSevenMan · Post by **LotusSevenMan** » Thu Jul 03, 2008 4:24 am

Thanks Kwackman12.
Good thought.
Now the battery to frame earth is good because it was a first thing I checked (along with the same at number 7, 10, and 15 on the what's causing this chart!!!).
That's not to say that the engine to the frame has a good earth though.
Can also try a seperate earth from something close (ie stat housing bolt to frame) as a secondary earth to eliminate this possibility.
If you look at the time I am posting this it's 'cos just woke up thinking about this damn problem. Was working out in my head a diode set-up to damp the initial needle swing etc perhaps.

Aaaaaaaagggggggggghhhhhhhhhhhh.

LotusSevenMan · Post by **LotusSevenMan** » Thu Jul 03, 2008 7:00 am

Couldn't wait.
Dressing gown on in sheltered garden open air 'workshop' at 5.45am. Neighbours think I'm a nutter anyway. Well if any of them saw me I'll have proved them right!!!!!

Anyway, did some frame to engine resistance checks. Well there is some loss. Only very slight but four times the battery to frame loss at that earthing bolt position just to the left of the battery and although small ohms wise it is significant enough IMHO.
So, have made up an earthing strap/lead from the top thermostat housing bolt to the battery negative. Why that bolt? Closest in terms of the sender position. Checked all parts of the barrels etc and now all at same potential as that bolt/earth.

It can't harm it and I do bl%dy well think it'll make a difference.
Geez it'd better otherwise that gauge is coming out and something useful, like an am/pm clock is going to be fitted in the now spare space!!!!!
Not really, but you get the idea.
Can't test it as very quiet here right now.
Later, later. later.

PS Fitted a quick release pair of connectors to the negative post on the battery to make removal easier while messing around. No undoing that frame earthing bolt anymore.

alanw · Post by **alanw** » Thu Jul 03, 2008 7:11 am

"Dressing Gown"

Not bare legs & SLIPPERS aswell

LotusSevenMan · Post by **LotusSevenMan** » Thu Jul 03, 2008 8:09 am

Err, bare legs yes, but steel toe capped site boots if you don't mind. Health and safety etc!!!

$\:D/$ $\:D/$ $\:D/$
It works!!!!! Steady temp gauge with no dipping on blipping!
Fantastic.

Downside? Another electrical problem has 'occurred'.
See new post.