Fuel and Temp Gauge

[Kintan]

So, this is not a 7v Regulator question. Why? Because I replaced that with a DIY one that was registering 7v and nothing happened.

The problem is this. The two gauges were working fine, no problems, so then I took out the air cleaner box to do some work on the air cutoff valve and when I put it all back together and fired it up, nothing. Here is the other funky part. I checked and I am pretty sure there was not a 7v Regulator in the bike in the first place....yeah I know strange.

So, are there any other reasons these two gauges would not be working? And I assume this is normal with the temp gauge not working, but the fan won't run either.

[Fred Camper]

Checked all the fuses? If you provide a ground to where the float plugs into the sender, it should rocket to full. Sounds like you are missing a necessary ground somewhere.

[WingAdmin]

That is odd, because the gauges find their ground through the sensors. Can you confirm that there is in fact +7v reaching the input side of both gauges, and that if you ground the output sides of the gauges (the sides that have wires that go to their individual sensors) that the gauges go to full scale?

[Kintan]

::EDIT::

Ok, I looked at the wiring diagram in my Clymer's to do some wire tracing. In the manual it does not show any type of "regulator" with the same color wires going to it. The only thing I saw was a "Temp Regulator". I would guess this is the same thing? Anyway, from that I saw that the same wire which takes the output from the 7v regulator, Green/Black, goes to both the fuel and temp gauge. I did not get the tach apart to check the wire going to the temp gauge but I already had the fuel gauge off so I checked the G/B wire going to that. It was reading 1.29v with the bike on. I then checked the regulator which was giving me 7.0v. Let's hope that helps. Tomorrow I will get the tach apart and check the temp gauge.

[WingAdmin]

::EDIT::

Ok, I looked at the wiring diagram in my Clymer's to do some wire tracing. In the manual it does not show any type of "regulator" with the same color wires going to it. The only thing I saw was a "Temp Regulator". I would guess this is the same thing? Anyway, from that I saw that the same wire which takes the output from the 7v regulator, Green/Black, goes to both the fuel and temp gauge.

That's correct.

I did not get the tach apart to check the wire going to the temp gauge but I already had the fuel gauge off so I checked the G/B wire going to that. It was reading 1.29v with the bike on. I then checked the regulator which was giving me 7.0v. Let's hope that helps. Tomorrow I will get the tach apart and check the temp gauge.

So the regulator (while hooked up) was reading 7 volts, and the green/black wire at the fuel gauge (at the same time) was reading only 1.29v?

[Kintan]

That's correct. I need to check the TAC but I assume it will be the same because the wire to the TAC runs from the fuel gauge.

[WingAdmin]

That's correct. I need to check the TAC but I assume it will be the same because the wire to the TAC runs from the fuel gauge.

Well that to me says you've got a corroded or bad connection between the regulator and the fuel/temp gauges. It should be reading the same voltage at the regulator and at the gauges (it's just a wire going between them). Here's an experiment: Connect a wire from the 7 volt output of the regulator to the 7 volt input at the gauges, and see if your gauges come to life.

[Kintan]

As much as I read that and go "duh" I didn't even think of that. I shall tomorrow!

[Kintan]

Ok, I just ran a wire directly from the 7v regulator to the fuel gauge (apparently I can't take apart the Tach to do that wire...). When I had the yellow wire from the Fuel Gauge Sender attached I was getting a reading of 0.20v from the wire from the regulator. When I detached that wire from the fuel gauge sender and just had a wire from the regulator I was getting 7.0v from the regulator wire. And the gauges did not work. Oh, if it matters I have about a half tank of fuel left.

I should also mention, I also ran a wire directly from the fuel gauge sender to the fuel gauge bypassing the yellow wire just in case that was causing a problem and got the same readings as above.

[WingAdmin]

If you put an ohmmeter on the yellow wire going to the fuel sensor, and the other ohmmeter lead to ground (battery negative), what reading do you get?

[Kintan]

I checked that too. With gas in it I was getting a reading of like 22 ohm or so. What I don't get is if I disconnect the sender from the gauge the power at the 7v regulator (I made a DIY one and added an extra output wire so I could check the power coming off at the unit) will read 7v but the second I connect the sender to the gauge the power at the regulator will read 1.2v. Just seems strange that the power at the actual regulator will drop when I connect that gauge. Makes me wonder if I did not make it right or something. This is what I get for not being horribly tech savvy on electrical stuff

[WingAdmin]

I checked that too. With gas in it I was getting a reading of like 22 ohm or so. What I don't get is if I disconnect the sender from the gauge the power at the 7v regulator (I made a DIY one and added an extra output wire so I could check the power coming off at the unit) will read 7v but the second I connect the sender to the gauge the power at the regulator will read 1.2v. Just seems strange that the power at the actual regulator will drop when I connect that gauge. Makes me wonder if I did not make it right or something. This is what I get for not being horribly tech savvy on electrical stuff

Your sensor resistance is just about spot on. I suspect the problem may be your DIY 7 volt regulator. How did you build it? If it is not capable of providing enough current, the voltage will drop quite precipitously and the gauges will not work, which is what sounds like is happening with your setup.

[Kintan]

http://bobsold.goldwingfacts.com/7vregu ... ematic.doc

That's the setup I used. I might be building it wrong. I am going to sit down later and see if i did.

[Kintan]

WOOHOO! Fixed it! I had the regulator plugged up wrong. Had two terminals backwards. Now it works

[thrasherg]

Congrats, Given your last readings I was going to also say the regulator is not up to the job, but you found the problem.. Hope you have many happy hours riding the bike and not fixing it..

Gary

[Fred Camper]

Just love a story with a happy ending like this one.

[BurnsYoFace34]

So question I put a after market tachometer on my bike which also has a fuel gauge an temp gauge connection whic wire should I hook up to get readings?

[Rambozo]

Since it is aftermarket, you will need to check the instructions that came with it. That should tell you what it is looking for from a temp sender and fuel sender. Usually they are resistive units, but the values can be all over the place. Was it something specifically made for your bike, or more universal?

[BurnsYoFace34]

Universal an it just says fuel wire lol so I'm guessing it's a wire from the sending unit

[Rambozo]

The problem is that there is no standard for sending units, especially fuel. Some go from 0 to 300 ohms, others go from 500 to 0 in the other direction. If you don't have the specs. you are just guessing. I take it the gauge didn't come with a sending unit for temperature? If you have no specs, wire up a couple of potentiometers to do some testing. I think the Honda senders are documented in the service manual for testing. The temp sender is an easy part to substitute, once you know what it needs to be, but the fuel would not be so easy.