Need help w/ Fuel Sender wiring on new tanks

[IFish4Tuna]

Hello - I just got done installing new tanks in my 1999 GW Bimini 306. Here is the original thread where I show the before & after pics and process.

1999 Bimini 306 - replacing fuel tanks.

Lesson learned. The fuel tanks need to be rinsed regularly, and the deck plate o-ring seals are prone to leaking. I have had this boat since 2005. About 5 years ago, I pulled the deck plate to have a look underneath. I saw A LOT of white jelly. Sadly - I thought that jelly was a protective...

www.greatgrady.com

Unfortunately after launching and fueling up, neither tank is registering fuel. I could really use some help here. I have to tell you I am a bit nervous about wiring to 300 gallons of fuel.....

I will post the before and after pictures. Excuse the use of the same yellow wire on the new installs, but I think you can visually trace them back to the original colors. Also below is the GW wiring spec, but I'm still confused.

Appreciate any help on this. Thanks in advance.
Ed

This is my original fwd tank


This is my original rear tank wiring. Note different sender and wiring.



This is my new fwd tank wiring



This is my new rear tank wiring



This is what GW offers for wiring specifications - which does not make sense to me.



Here is wiring diagram from user manual

 

[SkunkBoat]

The green wires go to ground(neg 12v) bus bar usually under dash

You need to run a ground wire from tank to tank and to battery/motor ground.(please use green or green/yellow wire...or black at the very least)
I know that seems redundant if the green wires are connected to the tanks and both to the ground bus but I've been down this road...

Main tank has pink and Aux tank has pink/white
Your yamaha gauge can only read one tank at a time.
The center pink wire on the switch goes to the gauge. The switch allows you to choose which tank you are reading.

FYI, when you change the switch, it takes awhile for the digital gauge to display the correct reading of the other tank. You have to wait for it....


I hope you did not paint the labels. Its good to have the capacity and mfg date visible.

 

[seasick]

As a quick test, run a wire from the ground tab on a tank to a battery negative post. ( you need a good ground).

Turn on the ignition and try both positions of the sender select dash switch (maybe marked, MAIN and AUX. As Skuntboat stated, wait a bout 30 seconds on each setting to see if you get a level reading (ignition has to be on but motor doesn't have to be started.
If one switch positions results in a reading of gas level than your tank is not grounded and will need a new ground.
If neither switch setting results in a reading other than empty, take the ground wire that you connected to the tank and touch it to the center pink connection on the fuel sender. With the ignition on, try both positions of the sender select switch and see if the level read changes. If it does but didn't for the first test, you have a bad connection in your new wiring or the sender is bad.
If nothing changes after these tests, you have a wiring problem somewhere between the sender connection and the dash gauge. That is not that simple to trouble shoot if you don't understand the wiring and function of the dash switch. It could be as simple as a loose wire on that switch or a bad switch. Testing is relatively simple assuming you can get to the back of the switch. If you get that far, take a picture of the back of the switch and post it. We can then tell you what terminals to play with to test out the switch and wiring

 

[IFish4Tuna]

Thanks Guys - I will print out and see what I can find tomorrow morning. I have already tried both positions neither with success (and have waited patiently). Yes I can access the switch easily on the console.

Do the connections look proper in the new images? Meaning pink in both is going to the center connection on the sender, and green in both is attached to both the sender's ground and also grounded to the tank. Or should it only be connected to either the tank or the sender?

I will run some resistance tests to the ground at the battery connection and also a restistance test to the connections attaching to the switch also.

I'll need a 2nd pair of hands. Well it will be fathers days so maybe I'll get some help

 

[SkunkBoat]

were you able to find the other end of the green wires?
Based on you diagram, they may go to the batteries not under the dash.

If they are not at ground, it will not work. Like seasick said, jump a ground from tank to the neg battery terminal and see if it works

 

[IFish4Tuna]

Not yet. I will validate that tomorrow. I think those green shown in the pictures are going to the ground on the battery, but I'll verify that with continuity test tomorrow.

 

[SkunkBoat]

those are intersting pipe fittings on the fuel hoses. are you sure they don't stick up too high?
Used to seeing the standard milled aluminum fuel pickups with plastic tube. Is there some custom metal fuel pickup tube?

 

[seasick]

I would not expect a green wire as the 'ground' so either is was replaced or that green wire is part of the ground bonding wiring if there is bonding. If it is bonding then the bonding is not connected to battery ground. Try the separate ground and if that works, that's good but you will need to find where that green wire goes.

 

[SkunkBoat]

Fuel sender ground is green. It does bond the tanks and there is one to the fill & vent
Same on my grady.

 

[seasick]

Fuel sender ground is green. It does bond the tanks and there is one to the fill & vent
Same on my grady.

Interesting: I am not an expert on bonding but I though that devices that are connected to the bonding common point would have directs connections that is dedicated conductor. The idea being that daisy chained devices can create ground loop currents. It may be that for devices that are not powered, ground loops are not a concern.
On vessels with shore power, aren't grounds separate from neutrals and are connected using an isolator at the main common ground bus?
Just by coincidence, I pulled the access plates on the senders on a 2002 Marlin two days ago. The wires were pink and black, no yellow.

 

[IFish4Tuna]

I don't know anything about bonding. Something else to read up on I guess.

Here are my notes from 3 hours of diagnostics today. I won't likely be able to get back to the boat until next weekend for next steps

Fuel sender diagnosis

• Testing of switch with no wires connected :
• Jumped at switch with tank switch set on fwd (top pressed pressed): center to top no continuity. center to bottom 1.8 on infinite setting
• Jumped at switch with tank switch set on rear(bottom of switch pressed): center to top no continuity. center to bottom no continuity

This makes me think the switch is bad (among other things). I would have expected to get a reading of zero on 2 of the 4 tests. But instead I got no continuity on 3, and a strange 1.8 reading. I don't know how to interpret the 1.8 value.

• Front tank ohm reading sender to ground - 43.2
• Rear tank ohm reading sender to ground - open (1) when set on 200 range. And .225 when set on infinite

I think the rear tank is not properly grounded and hence the goofy values.

• Pink @ switch to front tank pink lead - no resistance read .001 on infinite. This means no breaks / shorts in this wire. Good!!
• Pink @ switch to front senders ground 43.3 - also Good.

So the front tank seems like it has ground and and reasonable ohm reading (tank has 140 gallons of 150 capacity), but it is not showing as full on the gauge.

• Pink/white @ switch to rear sender ground - open (1) when set on 200. .226 when set on infinite
• Pink/white @ switch to rear tank pink/white lead no continuity when remove pink/white wire from the send. But if I leave it attached to the sender, I get a reading 1.8. If I touch to ground of the sender, I get the same value.

I was running out of time. I ran a 10 guage wire from rear tank threaded ground strip to the front tank. It did not resolve the guage issue. I will need to attached that green wire to the negative battery post on my next visit. I did not have enough time, and needed a 3 way crimp

I was not able to find the green wires which come from the tanks up to the console.
I took the panel off to inspect the rear of the guage. It was not labled so I could not verify voltage, but I'm pretty sure it is not a problem because the guage is flashing empty (bottom bar flashing). If it did not have power I don't think it would read time, trip, or show flashing.

So nex steps is ground the green to the batter, and look for a replacement switch. I do think the rear tank sender is not working properly but I did not test it with both the pink and green disconnected. I'll need to do that on next visit also.

 

[SkunkBoat]

Interesting: I am not an expert on bonding but I though that devices that are connected to the bonding common point would have directs connections that is dedicated conductor. The idea being that daisy chained devices can create ground loop currents. It may be that for devices that are not powered, ground loops are not a concern.
On vessels with shore power, aren't grounds separate from neutrals and are connected using an isolator at the main common ground bus?

What I mean to say is that the green fuel sender wire is directly connected to the aluminum tanks and to the negative battery terminals which is in effect "bonding" them with each other, the fuel fill & vent, the motor chassis. I used the term "ground" interchangeably with "negative" or "DC common".

I've always seen "bonding" wires that are green with yellow stripe but green is also used..apparently by Grady. It can be confusing because AC ground wire is green also. On a vessel with AC there should be an isolator or an isolation transformer and the isolated AC green wire gets connected to the Neg bus (the neg bus connects to the motor which is the connection to seawater)
A green wire should not be carrying any current under normal conditions. In the fuel sender/gauge circuit the green wire does not (should not)carry current. The gauge reads a voltage drop between the pink wire and the negative bus (thru the cable that goes to the motor).
Also, on a boat with AC power, the DC neg should be yellow wire to prevent confusion with the HOT black AC wire. Grady does not conform to this.

Just by coincidence, I pulled the access plates on the senders on a 2002 Marlin two days ago. The wires were pink and black, no yellow.

IFish4tuna's new sending units came without wire. The yellow wire is just what he had lying around. Its really not a good idea because it will confuse people now and in the future.
In his old picture the wires on the senders are pink and black but the black wire connects to the green wire in Grady's harness. The Grady diagram shows the greens going directly to the negative battery terminals. Mine is the same and there is a set of three green wires at the battery.
I added a wire between tanks and to the neg terminal because I have had a few odd problems with the digital fuel gauges on my yammies and then on my zukes ( the dealer had disconnected my new wire and could not get gauges working right)

 

[SkunkBoat]

So nex steps is ground the green to the batter, and look for a replacement switch. I do think the rear tank sender is not working properly but I did not test it with both the pink and green disconnected. I'll need to do that on next visit also.

You should be able to test the gauge without a switch. Connect the pink sender wire directly to the gauge to read main tank or pink/white to read Aux tank.
You can test the switch without wires attached using your ohmmeter

 

[IFish4Tuna]

Well, I've discovered I have more than 1 problem. The switch at the console was bad, and in addition, the sender at the rear tank is also faulty. I replaced the switch and now the front tank reads properly. I am unable to get a resistance reading when I jump from sender to ground on the top of the sender unit (I was able to get a reading on the front tank) and I've traced all the wires so I know they are good (resistance checked). So I've ordered a Moeller reed sender. I'll have to burn through some fuel before swapping it out since the tank is full right now. This is pretty disappointing since the tanks and senders are new.

 

[everwhom]

Well, I've discovered I have more than 1 problem. The switch at the console was bad, and in addition, the sender at the rear tank is also faulty. I replaced the switch and now the front tank reads properly. I am unable to get a resistance reading when I jump from sender to ground on the top of the sender unit (I was able to get a reading on the front tank) and I've traced all the wires so I know they are good (resistance checked). So I've ordered a Moeller reed sender. I'll have to burn through some fuel before swapping it out since the tank is full right now. This is pretty disappointing since the tanks and senders are new.

Just checking that when you were measuring the resistance on the rear tank sender, you had completely disconnected the wires from the boat? What reading did you get? Zero (i.e. short circuit) or infinite?

 

[IFish4Tuna]

Hello, yes - fully disconnected, at the sender unit. The rear tank however is/was still grounded (daisy chain to front tank, then to battery terminal.

I get/got the same readings with the sender wire and ground tab connected also.

Resistance Test Results	Infinite Setting on Meter	200 Setting on Meter	Fuel Level compared to capacity
Front (working)	.0069	73 (was reading 43 when full)	2/3 full
Rear (not working)	.229	1	Full

 

[everwhom]

Hello, yes - fully disconnected, at the sender unit. The rear tank however is/was still grounded (daisy chain to front tank, then to battery terminal.

I get/got the same readings with the sender wire and ground tab connected also.

Resistance Test Results	Infinite Setting on Meter	200 Setting on Meter	Fuel Level compared to capacity
Front (working)	.0069	73 (was reading 43 when full)	2/3 full
Rear (not working)	.229	1	Full

Yeah looks like the rear sender is shorted out. At least they aren't too horribly expensive to replace...

 

[Byram]

Do you have nitrile or cork gaskets on the sender. Im ordering new for my boat and wema/kus has an option to choose either one .

 

[everwhom]

Do you have nitrile or cork gaskets on the sender. Im ordering new for my boat and wema/kus has an option to choose either one .

I went with the "viton" gasket from KUS when I replaced a sender this year. I'd heard cork can deteriorate... I don't know what gasket was on the previous sender (some kind of rubber, so I'll assume nitrile), but the gasket or screws definitely leaked a bit. When I went to replace, I could smell fuel which was a bit troublesome -- I was worried that I may have some bigger problem with my tank. Fortunately after replacing, the fuel smells went away entirely!

 

[IFish4Tuna]

Do you have nitrile or cork gaskets on the sender. Im ordering new for my boat and wema/kus has an option to choose either one .

They are rubber/not cork ( Moeller)