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Author Topic:   Fuel Sender Wiring
Dauntless_14_TX posted 08-12-2009 03:44 PM ET (US)   Profile for Dauntless_14_TX   Send Email to Dauntless_14_TX  
I was having problems with a faulty fuel gauge last time out so when I got back to the garage I opened up the bilge to inspect the sender unit. As I suspected one was was completely broken off. Though it looks like it was "soldered" on to the sender to the "NEG" terminal where another wire was attached. My question is what is this "third" wire. I thought there was 2 wires for the gauge, a negative and a positive-sending wire. Only seems to be 2 connections, the center "sender" terminal and a "negative" terminal on the outside edge of the top. So what is this third wire? TO clarify a bit more the positive sender wire and one of the negative wires are taped together and the third is a stray that I am not sure where it goes. Its a Dauntless 14, so space to see where it may lead is very tight at best. Any help would be great, and I'm going to try and trace some wires this weekend and play with some attachments to see if I can't get it to work.
White Bear posted 08-12-2009 05:17 PM ET (US)     Profile for White Bear  Send Email to White Bear     
Most likely a ground wire.
fishgutz posted 08-12-2009 09:19 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
I just checked my Dauntless 14, The green wires look to be both ground wires. One is screwed to the top of the sender on the tank and the other one is connected to a tab on the same sender thing. After that they just disappear into darkness under the floor. Good luck, man.
I'll post a link to a picture of my sender.

jimh posted 08-12-2009 09:43 PM ET (US)     Profile for jimh  Send Email to jimh     
Describe the color of the insulation on the wires which you find near the fuel tank and the fuel level sender. In marine wiring there is generally a color code used for wiring insulation to identify the wire function. It is not possible to associate a wire function by arbitrarily assigning the wire an ordinal number such as first, second, or third.
jimh posted 08-12-2009 09:53 PM ET (US)     Profile for jimh  Send Email to jimh     
Also, give the wire gauge size. The wire gauge size is an important factor in deducing what the wire function might be.
fishgutz posted 08-12-2009 10:06 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
The one ground that is screwed down is screwed to a dedicated grounding screw. Fuelsender1.jpg Fuelsender2.jpg
fishgutz posted 08-13-2009 08:19 AM ET (US)     Profile for fishgutz  Send Email to fishgutz     
It was only about 100 degrees in my garage last night when I took those pictures so I can't give too much detail.

The green wires seem to be ground wires. I do not know where they go. They do go off in two different directions. The one on the tab goes with the pink wire and the one screwed down goes off by itself in the direction of the fuel fill. The pink wire is the fuel sender wire that eventually gets to the fuel gauge. They are somewhat larger gauge wires I'd say at least 12 gauge maybe 10.

That area is very small and dark. In fact I couldn't see much myself. I simply put the camera into the inspection port and started snapping. Those 2 pics turned out the best.

Dauntless_14_TX posted 08-13-2009 09:23 AM ET (US)     Profile for Dauntless_14_TX  Send Email to Dauntless_14_TX     
Thanks Fishgutz,

The pictures were a huge help. I have the same setup, the one ground attached to the tab that runs who knows where, and the other one that was corroded off. Though instead of a ground screw, it was another tab that was soldered to the edge of the sender plate and had since corroded off. Hopefully I'll be able to put a ring terminal on the end of it and reattach it to the sender. Though still unclear as to why there are 2 grounds? One for the gauge and the other as a hard ground for the tank? I'm going to tackle it this weekend and will take some before and after pictures, as pictures are worth a 1000 words. Thanks for the help and I'll let you know what I find out and get it working correctly.

fishgutz posted 08-13-2009 09:39 AM ET (US)     Profile for fishgutz  Send Email to fishgutz     
Perhaps the extra ground wire has something to do with static electricity while filling the tank? jimh may know more about this.
jimh posted 08-13-2009 12:08 PM ET (US)     Profile for jimh  Send Email to jimh     
It is quite typical on a Boston Whaler boat --or on any boat which conforms with the recommendations of the ABYC and or USCG--that all metallic components of the fuel system are bonded together with a 10-AWG conductor with green insulation.

It is quite normal that only one conductor is installed under a binding terminal post. The bonding conductor is typically wired in a daisy chain manner, that is, it loops from component to component. This means that a component in the middle of the daisy chain of bonding conductors will have two conductors attached to it. The conductors will properly be attached to separate terminals or bindings on the component.

The bonding conductors typically terminate into a bonding plate on the hull that is in contact with the sea, or on boats without such a bonding plate, the bonding conductors will be connected to the battery negative terminal. The battery negative is generally bonded to the engine block of the outboard motor. Since an outboard motor usually has some exposed electrical anodes in contact with the sea, you can figure that the battery negative terminal is in contact with the sea.

In the REFERENCE section there is an article discussing the use of insulation color codes to identify the function of a wire in Boston Whaler boats:

The color of the wire insulation on the fuel sender is PINK.

The color of the wire insulation on the bonding conductors is GREEN.

This information should be useful in identifying the function of the conductors associated with the fuel tank.

fishgutz posted 08-13-2009 12:25 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
Thanks Jim. I have a chart from Boston Whaler that came with my boat that has all the wire color coding listed. Most wires listed don't exist on my small boat but what I do have is listed.

Dauntless_14_TX posted 08-13-2009 02:55 PM ET (US)     Profile for Dauntless_14_TX  Send Email to Dauntless_14_TX     

Thanks for the detailed analysis. Makes sense to me now why there is an extra ground attached. Biggest problem will now be maneuvering in the bilge area to get the corroded wire reattached. Its great having the indeck fuel tank, except when you have to do any work through a small access hole in the motor well.

L H G posted 08-18-2009 07:48 PM ET (US)     Profile for L H G    
The green wire attached with the flat slide-on connector is the fuel GAUGE ground, the other green wire is the fuel TANK ground.
jimh posted 08-18-2009 08:25 PM ET (US)     Profile for jimh  Send Email to jimh     
How do you know?
fishgutz posted 08-18-2009 08:59 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
LHG is correct. He just knows. He's supersmart.
jimh posted 08-18-2009 09:49 PM ET (US)     Profile for jimh  Send Email to jimh     
The two ground circuits are in common. They are connected together at the fuel tank component to which they are bonded. You cannot refer to them as separate circuits. They are branches of the same circuit: the GROUND.

You may have isolated ground circuits, but the concept of an isolated ground is one which is kept separate from the common ground, except to join it at one point. The point at which all ground circuits come together is the COMMON GROUND. However, it is extremely unlikely that the COMMON GROUND on a boat would be a fuel tank fitting.

The COMMON GROUND point of a small boat electrical system is typically the BATTERY NEGATIVE TERMINAL COMMON BUS. On really simple installations the battery negative terminal itself becomes the common point, and two or three wires are connected to it. As the electrical system on a small boat become more complicated, there should be a battery negative COMMON NEGATIVE BUS, a bus terminal to which many negative leads can be connected.

Typically the battery negative common bus will bond together the negative terminal of ALL BATTERIES. The negative leads from all secondary distribution centers will connect to the common bus. Leads from individual loads which are not connected to secondary distribution centers will also connect to the COMMON NEGATIVE BUS.

number9 posted 08-18-2009 09:49 PM ET (US)     Profile for number9  Send Email to number9     
Stands to reason a proper tank ground would use a ring terminal instead of a spade type disconnect.
jimh posted 08-18-2009 11:15 PM ET (US)     Profile for jimh  Send Email to jimh     
The BONDING circuit should not have any current flowing on it, even the small current needed to deflect a meter.
L H G posted 08-19-2009 12:19 AM ET (US)     Profile for L H G    
I know because I just installed a replacement electric fuel gauge sender in the ALUMINUM tank of my 1975 Outrage 19. For an electirc fuel guage to work, the sender wiring was configured exactly as Fishguts shows, with pink wire to the gauge sender terminal, and green spade connected wire to the gauge negative terminal, but no third ground wire. Now on an aluminum tank, you don't need to have the tank ground connected to this same sender metal component, and Whaler connected it elsewhere on the tank, but evidently you do on a plastic tank like the Dauntless has, since there is no other metal on the tank. The Dauntless may not have the Dynaplate on the transom, below the waterline, like the 1st and 2nd generation Outrages do, and must use the battery for the tank ground.

On all of my Outrages with internal tank, the green wires are a separate fuel tank ground system and don't appear to have any connection to the boat's batteries, from a fitting on the tank, and on the fuel filler, grounded into the water by the Dynaplate on the transom. This system is designed to protect the fuel system and get rid of any static electicity charge that may occur, preventing an explosion.

fishgutz posted 08-19-2009 10:20 AM ET (US)     Profile for fishgutz  Send Email to fishgutz     
I'm not sure yet where the extra screwed on green ground wire goes. The tabbed green wire goes with the pink wire in the large wire harness to starboard. The extra screwed on green wire goes to the port side in the direction of the fuel fill. That would make sense to ground the sending unit to the fill collar to help eliminate static. Wouldn't it?
jimh posted 08-19-2009 11:58 AM ET (US)     Profile for jimh  Send Email to jimh     
All metallic (or conductive) components of the fuel system should be bonded together. The metal fitting on the fiberglass tank should be bonded to the next element in the fuel system. If that is the filler fitting, that is probably where the as-yet unidentified green conductor goes.

Usually an isolated ground will use an insulation color of black with a stripe. The REFERENCE section lists several conductors of black with various color stripes which are isolated grounds for instruments. Using a green conductor is really not proper for the fuel level sender ground. Black with a green stripe might have been more appropriate. Or green with a white stripe. Solid green is for bonding conductors.

fishgutz posted 08-19-2009 12:35 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
When I had the floor up on my Dauntless 14 a few years ago, I should have made note of where those wires all went. I also should have moved the sender to a center location on the tank. I think there was an alternate location there. It sure would have made the gauge more accurate. My gauge doesn't move off full until the tank is at about 1/3 full.
L H G posted 08-19-2009 02:24 PM ET (US)     Profile for L H G    
I would agree with Jim that the negative wire from fuel sender to fuel gauge should be black, as are all of the negative wires in the instrument wiring/ignition harness.

Don't know why Whaler used green to the back of the gauge.
Maybe just to show it is the sender neg as opposed to the neg jumpers from the other gauges in the instrument cluster.

number9 posted 08-19-2009 03:09 PM ET (US)     Profile for number9  Send Email to number9     
I did a bit of research last night after posting a reply and reading Jim's replies. First downloaded the current Outrage 180 owner's manual from BW to look at a current wiring diagram for a newer poly tank. That showed one of the green "ground" wires going to the common ground buss and the other to the fuel fill.

To get a better understanding of the gauge/sender operation looked at three different manufactures' sites and found that some senders have two leads for the sender unlike the Moeller type with a spade disconnect and a center terminal post.

In common with all the analog gauges is a send and a negative or ground connection that connect to the corresponding sender terminals or wiring. On the 180 the gauge ground would be wired to the ground buss. The gauge operates by applying a voltage to the resistance just as an ohmmeter would.

The BONDING circuit should not have any current flowing on it, even the small current needed to deflect a meter.

I agree but don't see how BW and other builders are doing proper tank bonding if doing so using a fuel sender.

http:/ / www. moellermarine. com/ sites/ moellermarine/ file/ Gauge%20an d%20Sending%20Unit%20Wiring%20Diagram%20and%20Industry%20Recommendations . pdf

number9 posted 08-19-2009 03:14 PM ET (US)     Profile for number9  Send Email to number9     
Maybe this will work?

http:/ / www. moellermarine. com/ sites/ moellermarine/ files/ Gauge%20a nd%20Sending%20Unit%20Wiring%20Diagram%20and%20Industry%20Recommendation s. pdf

fishgutz posted 08-19-2009 04:10 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
Number 9, They aren't using the fuel sender for the extra ground. The ground wire for the sender and the ground wire for the tank just happen to be attached to the plate on the tank that the sender is mounted to. See my picks above. So the ground wire for the sender will in fact have current running through it. The tank ground, I'll bet doesn't have current running through it, or shouldn't. I think that ground wire just connects things together and simply dead ends at certain fittings like the fuel fill.

Some larger boats and especially large sailboats will have every piece of metal "grounded" or connected together. No positive wires and no current involved. Mast, railings, lead keel, stays, etc. all connected together.

fishgutz posted 08-19-2009 05:54 PM ET (US)     Profile for fishgutz  Send Email to fishgutz     
Slight correction.
The screwed down green ground wire goes with the pink wire.

The tabbed green wire goes to the collar of the fuel fill cap. That is the only place it goes.

The sender ground wire (the screwed down one) goes with the pink wire into the wire harness. See my pictures above.

I don't know where the bundled green and pink wires go. There is no green wire in my dash only a pink one. I will post a picture of the back of my dash after I load it on Photobucket.

fishgutz posted 08-19-2009 06:47 PM ET (US)     Profile for fishgutz  Send Email to fishgutz Gauge3.jpg
Look Ma, no green wire.
Dauntless_14_TX posted 08-25-2009 09:50 AM ET (US)     Profile for Dauntless_14_TX  Send Email to Dauntless_14_TX     
After being sick a week ago finally got a chance to work on the boat. I replaced the connectors on all the wires to the tank because if I was going to do a couple of them might as well do them all. The pink wire was attached to the positive terminal and the attached green wire with it was screwed down on the outside. The tabbed ground does indeed go to the fuel fill, after much contortion to try and see where it went. Took the boat out last sunday and watched as the fuel gauge "worked" but still bounces a lot due to being a float gauge. Thinking about adding a fuel flow sensor to my Lowrance unit so I know just how much gas I am using.

This may need to be in a new thread, but has anyone installed one and how well does it work?

fishgutz posted 08-25-2009 10:00 AM ET (US)     Profile for fishgutz  Send Email to fishgutz     
Wow, your gauge moves? Mine stays at full until it is down to about 1/4 to 1/3. The boat has to be perfectly level or even a little nose down for the gauge to be even a little accurate.
I'll have to pull the float. If it is a lever type arrangement I'll have to bend it a bit.

I had the floor up on the boat a few years ago and I thought there was a center spot to mount the sender under the helm seat. That would be a more accurate location. In the meantime, I'll just live with it.

Dauntless_14_TX posted 08-26-2009 08:35 AM ET (US)     Profile for Dauntless_14_TX  Send Email to Dauntless_14_TX     
When its half full it bounces between full and 3/4 a bit. Though I know what you mean about it not moving until the tank is nearly empty. Hoping the fuel flow meter will be a huge improvment. Though a buddy of mine recently installed a capacitance fuel gauge in his boat and works great according to him, more accurate and needle doesn't bounce around. I don't know much about it, but perhaps someone on this forum has more experience with one.

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