Fuel Gauge show empty "ON" and "Start"

[bebeard]

hi all,

I have a 1977 Challenger Mark IV with a MERC 1500 150 hp. I Have just installed a new internal wiring harness and ignition switch. I have just tested and fired up the motor, and all looks and sounds good.

The one thing that I have a question about is that when I put the key in the ignition the fuel gauges show full (Which they are), however when I put the key in the "ON" or "START" positions, the fuel gauge show empty?

Does anyone have any ideas? suggestions on where I should start looking?

Thanks,

Brook

 

[hkeiner]

Re: Fuel Gauge show empty "ON" and "Start"

The fuel system troubleshooting guide at the below Teleflex link may be of help. While your gauge and sender may be of a different brand, the troubleshooting steps and principles should still apply.

http://ww2.tflx.com/tech.html

 

[bebeard]

Re: Fuel Gauge show empty "ON" and "Start"

Thank you for the post,

I will take a look at the site you suggested... but also to let you know I am getting fuel to the motor, it starts just fine, its just my gauge.

Brook

 

[hkeiner]

Re: Fuel Gauge show empty "ON" and "Start"

I understand. The trick is to figure out if your problem is with the sender on the fule tank, the gauge on the dash, or the wiring.

 

[bebeard]

Re: Fuel Gauge show empty "ON" and "Start"

Thanks for the response,

The ignition switch is brand new and just installed.... is this where my supply would come from for the guages or would it come directly from the battery?

Brook

 

[hkeiner]

Re: Fuel Gauge show empty "ON" and "Start"

Is this where my supply would come from for the guages or would it come directly from the battery?

Power to the gauge is most likely coming from the "accessories" connection on the ignition switch. If you don't have a wiring diagram for your boat and you can not visually track the wiring from the gauge to the power source, then use an ohmmeter and voltmeter to figure it out. With battery disconnected, use an ohmmeter to check for continuity (or not) between the gauge and the possible power sources. With battery connected, use a voltmeter to check the voltage at the gauge when the ignition key is turned off and on. These steps should answer your question with more certainty.

 

[bebeard]

Re: Fuel Gauge show empty "ON" and "Start"

Thank you very much!!

This is the information that I need to get started. I am attaching a wiring diagram for my boat... Is there a "standard" wire colour for accessories?

"With battery disconnected, use an ohmmeter to check for continuity (or not) between the gauge and the possible power sources." - I I should take the gauge out of the console, use the ohmmeter from wiring on the back of the gauge to the ignition switch?


"With battery connected, use a voltmeter to check the voltage at the gauge when the ignition key is turned off and on." - What voltage should it be? do you know?

Thanks so much!

Brook

 

[bebeard]

Re: Fuel Gauge show empty "ON" and "Start"

Hello,

I forgot to post the wiring diagram..

Brook

 

[hkeiner]

Re: Fuel Gauge show empty "ON" and "Start"

The wiring diagram you have is for the motor (i.e., mostly of what is under the cowl) and not for the boat (i.e. dash gauges, key switch, lighting systems, and such) . My guess is that you do not have a wiring diagram for the boat and so have to do the ohmmeter/voltmeter steps to determine the wiring for your fuel gauge.

"With battery disconnected, use an ohmmeter to check for continuity (or not) between the gauge and the possible power sources." - I I should take the gauge out of the console, use the ohmmeter from wiring on the back of the gauge to the ignition switch?

There is no need to remove the gauge from the dash if you can reach the wires from behind. On my boat, I can crawl under the dash and access the back side of the gauges and associated wiring. If you can't do that, then your only choice may be to remove the gauge panel to access the wiring.

"With battery connected, use a voltmeter to check the voltage at the gauge when the ignition key is turned off and on." - What voltage should it be? do you know?

The voltage would be the same as your battery's voltage, about 12.5V depending on how well charged your battery is. You are not testing the voltage level but whether there is voltage when the key is turned on and that there is no voltage when the key is turned off. If so, then the gauge is connected to the key switch and not directly to a 12v terminal fed directly by the battery.

Having said all that, it is most likely that your gauge is properly connected to the key switch, as your first post indicated that the gauge reads differently when the key is on and when it is off. The "A Basic Gauge Test" guide on the previously provided Teleflex link explains the gauge and sender troubleshooting tests pretty well.
.

 

[bebeard]

Re: Fuel Gauge show empty "ON" and "Start"

The wiring diagram you have is for the motor (i.e., mostly of what is under the cowl) and not for the boat (i.e. dash gauges, key switch, lighting systems, and such) . My guess is that you do not have a wiring diagram for the boat and so have to do the ohmmeter/voltmeter steps to determine the wiring for your fuel gauge.


-- I wasn't sure about the wiring diagram... my boat is a 1977 Challenger Mark IV and has been "wired" several times over, so this might be a chore... I will get my ohmmeter out and start my testing...


There is no need to remove the gauge from the dash if you can reach the wires from behind. On my boat, I can crawl under the dash and access the back side of the gauges and associated wiring. If you can't do that, then your only choice may be to remove the gauge panel to access the wiring.

--- I will take a look at this, I believe I can get to the wires from under the dash...

The voltage would be the same as your battery's voltage, about 12.5V depending on how well charged your battery is. You are not testing the voltage level but whether there is voltage when the key is turned on and that there is no voltage when the key is turned off. If so, then the gauge is connected to the key switch and not directly to a 12v terminal fed directly by the battery.


---- I will take a look as this as well, if I go out to my boat and look at my gauges, the fuel gauge shows full even before I put my key in.... but will perform more test to confirm....


Having said all that, it is most likely that your gauge is properly connected to the key switch, as your first post indicated that the gauge reads differently when the key is on and when it is off. The "A Basic Gauge Test" guide on the previously provided Teleflex link explains the gauge and sender troubleshooting tests pretty well. I suggest that you first check the resistance of the sending unit, using an ohmmeter, to see if it is within spec and then go from there.

-- Thank you for all the information.... you have given me a great start... and I will post more information as I am able to test...

--- it has been raining here for the past day or so, so it might be little bit before I can test more.

Thanks for everything!

Brook
.

Thanks for everything!

Brook

 

[bebeard]

Re: Fuel Gauge show empty "ON" and "Start"

hello,

I got my multimeter tester out, and started looking at it...

To test the Voltage... do I use the DCA or DCV seting?

and what position to I put it on 1000, 200, 20, 2000m, or 200m?

Same with the OHM test...

Do I use 2000k, 200k, 20k, 2000, or 200?


Thanks,

Brook

 

[hkeiner]

Re: Fuel Gauge show empty "ON" and "Start"

When you are testing voltage, you select DC current (not AC current) on the multimeter. When you are testing resistance, the specs for the sender will determine what ohm range to select on the multimeter. If you do not know what this means or do not know what the various dial settings on your particular multimeter mean, you should read the instructions for your meter. If you do not have instructions for your meter, search the internet for general instructions on how to use a multimeter. I am sure they can be found out there on the internet somewhere.

Good luck. I am sure you will be able to troubleshoot your problem using a multimeter.

 

[bebeard]

Re: Fuel Gauge show empty "ON" and "Start"

good day,

Thanks for the info and I did a search on what settings to use on my meter, and also wanted to let you know that I disconnected all other wires from my battery except for the mains. The fuel gauge did not power up with the key switch, so you have given me a place to start looking..

thanks again,

Brook