Islander 268 fuel help

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Cedarman

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Hey all,

I am newer to the community. I have a 99 268 Islander with new twin 200 mercs. I am very happy with it especially after the repower.

I am having issues with my fuel system and am hoping one of you has the knowledge I need. Currently we only run on the one tank. fill closest to the bow. My understanding is it is a 135 gal tank. The rear fill is for the reserve 65 gal tank. Am i wrong and have this flipped? The tank with the rear fill is full of bad fuel and i need to drain it which is why i do not use it

recently my boat stopped registering my fuel level which is very concerning and i'd like to fix it asap. Does anyone know where the fuel sending unit is and which one my boat requires? my local shop did not know and suggested i come here for an answer

Thanks all!
 
Can you use fuel flow from your Mercury on your MFD? At least Suzuki and Yamaha are spot on.
If you are lucky the part number is visible on the old fuel sender, if not then the best way to get a new fuel sender is to pull the old and measure it's depth.
Chris
 
Sardinia306Canyon said:
Can you use fuel flow from your Mercury on your MFD? At least Suzuki and Yamaha are spot on.
If you are lucky the part number is visible on the old fuel sender, if not then the best way to get a new fuel sender is to pull the old and measure it's depth.
Chris
Click to expand...
Hi Chris, Yes my Electronics show my burn rate. around 7 gals per hour for each motor @ 30 mph. My first concern is am I running off of 135 gal or 65 Gal. Next is location of the sending unit so I know which part of the boat to cut open to get it. Rear dance floor or between the front seats on the floor

Thanks for the reply though
 
I use for many years the fuel level from engine burn, not from the notoriously unreliable fuel senders.
When you refuel you add the correct value and then the digital gauges show level oand in the upper right edge the remaining fuel is shown, but on my Garmin 74 and 84 series.

I don't know your boat but i never saw a boat where it is needed to cut a hole to get to the fuel senders, they are usually be under a "pie plate", the round plate on the floor. Pry or screw it/them open and you will find the fuel sender below.

Chris
 
Below is a thread I created on replacing fuel tanks on a 1997 Islander 268. It pretty much explains everything you need to know. The forward tank is 134 gallon main tank. The aft tank is the aux tank which is 72 gallons in my boat.

You need to get the length of the sending unit. It's located under the pie plate in the forward part of tyour cockpit. They have to pull it out of the tank and measure it. Replace with correct length WEMA sending unit. I can't find the length in my notes.

Hookup1

Thread '268 Islander Fuel Tank Replacement'

Decided that this is the year to replace my 25 yo fuel tanks. No leaks. I plan to keep the boat. I'll document the process here.

Pulled the hatch. This hatch was rebuilt a few years ago with Coosa board. Looks good and feels solid. Hatch was set with 3M 4000 - kept everything sealed. Some difficulty cutting with blade to get it up. Not sure what it will go down with. Deck ports were caulked in from the underside as well. Kept the tanks dry.

1 Rebuilt hatch.jpeg

I also put plastic over the fill, sending unit and pickup. This deflects any water away from the busy area of the tank.

2 Tanks uncovered.jpeg...
  • Like
 
If its like every other boat, There are 6" pie plates at each end of each tank.

The sending unit is under the rear (toward stern) pie plate of each tank along with the fuel pickup hoses

The fuel Fill/vent hoses are under the fwd pie plates.

There is a label on top of each tank with its capacity.

The pie plates allow you a peek but it would probably be better to pull up the deck. All you need is a razor knife and a screw gun.
 
1st... if what you posted about the local shop is true... never go back there again. Replacing a fuel sender is one of the EASIEST things to do - and also very common. It's inline with replacing a spark plug in a 1990 Chevy truck with a small block.

You shouldn't have to cut anything open - either an access plate or a screwed down hatch would simply be removed. Remove the fuel sender... take it with you to a local shop (NOT the one you previously mentioned :) ) and then go back and re-install.

However, it would be prudent to first double check and test the sender wires going to the dash by grounding the pink wire. If everything from the sender to the gauge is good, then the sender is bad.

If you have a WEMA style sender, you may find a part number on it. I can't recall if the arm-style does... it may depend on which particular brand is in there now.
 
Did the gas gauge work correctly after the repower? The following test is valid for standard tank wiring. Some boats with Mercury rigging and command link instrumentation use a different wiring arrangement for the level sensors and trouble shooting is trickier.What displays/gauges do you have for the motors. Did you have the ability to display both tank levels, one on each gauge?

Before assuming the sender is bad make sure the dash switch that selects one of the two tanks is in the correct position. You have a sender for each tank but the dash gauge can only display one of the tanks at a time.
When you pull the pie plate and see the sender, you will see a pink wire connected to it. If you unplug that wire the gauge on the dash should read empty (give it a bit of time to settle). If that works, connect the pink wire to a good ground. The dash should read full. If those two things don't check out, the problem may be in the wiring, the gauge or perhaps the tank ground

WEMA senders are now made by KUS.
 
sorry i think I need to clarify, I do not have a analog gas gauge. I have 2 Lowrance HDS 9's and the Larger mercury smart gauge. These are all connected together through the nema network. When we purchased the boat it had etec's (same electronics less the merc gauge). Yes the digital gauge worked before. After the repower the digital gauge did work for a very short time. Now it shows empty all the time.

Thanks for all the help so far
 
Ok that changes everyting...
When the fuel consumption based fuel level worked after the repower then something may got reset during winter.
Check first on your Lowrance (what i can't help you with) if the HSD9 is showing fuel flow, if so then the HDS9 is getting fuel flow data.
in this case i would first check the settings on the HDS9, there is most likely some wrong setting.
If you can't see any fuel flow realted data on the HDS9 then there may be a problem with your new Mercury engines not ending fuel flow data and i cant help you with Mercury either.
Can you see fuel flow on the Mercury Gauge? If so then the outboard/s send fuelk flow data and the problem is again wither NMEA2000 connection between Mercury and Lowrance or again a Lowrance setting is wrong.
What Mercury engines you have? Can they send fuel flow data?
You are writing of NMEA2000 network, not the old NMEA183, correct?
Chris
 
Cedarman said:
sorry i think I need to clarify, I do not have a analog gas gauge. I have 2 Lowrance HDS 9's and the Larger mercury smart gauge. These are all connected together through the nema network. When we purchased the boat it had etec's (same electronics less the merc gauge). Yes the digital gauge worked before. After the repower the digital gauge did work for a very short time. Now it shows empty all the time.

Thanks for all the help so far
Click to expand...
OK. Look for the pink wire and short it to ground. See if the gauge reads full. If so, the sender is probably bad
 
Cedarman said:
sorry i think I need to clarify, I do not have a analog gas gauge. I have 2 Lowrance HDS 9's and the Larger mercury smart gauge. These are all connected together through the nema network. When we purchased the boat it had etec's (same electronics less the merc gauge). Yes the digital gauge worked before. After the repower the digital gauge did work for a very short time. Now it shows empty all the time.

Thanks for all the help so far
Click to expand...
No worries. The initial check is still exactly the same - regardless of what things downstream are reading the signal, the float is still the same 'ol thing. Start there.
 
DennisG01 said:
No worries. The initial check is still exactly the same - regardless of what things downstream are reading the signal, the float is still the same 'ol thing. Start there.
Click to expand...

One of my previous boats had Mercs with command link gauges. Although the senders in the tanks were the conventional type electrically, the concept of a pink wire did not apply. The mercury had a special multi purpose harness that used a 5 volt reference voltage and a voltage divider circuit that converted the sender signal from a resistance varying device to a voltage device. So instead of representing tank level with an ohm range, it sent a voltage somewhere between 0 volts and 5 volts.
One thing you didn't want to do was ground the 5 volt reference.
 
seasick said:
One of my previous boats had Mercs with command link gauges. Although the senders in the tanks were the conventional type electrically, the concept of a pink wire did not apply. The mercury had a special multi purpose harness that used a 5 volt reference voltage and a voltage divider circuit that converted the sender signal from a resistance varying device to a voltage device. So instead of representing tank level with an ohm range, it sent a voltage somewhere between 0 volts and 5 volts.
One thing you didn't want to do was ground the 5 volt reference.
Click to expand...
Yes, once a system moves into the 20th century and out of the 19th century :) with a canbus type thing, it all becomes digital. However, the sender is still 19th century - everything else is downstream of that. So the same method can still be applied - whether the sender is feeding the canbus or you are "faking" it, it's all the same.
 
DennisG01 said:
Yes, once a system moves into the 20th century and out of the 19th century :) with a canbus type thing, it all becomes digital. However, the sender is still 19th century - everything else is downstream of that. So the same method can still be applied - whether the sender is feeding the canbus or you are "faking" it, it's all the same.
Click to expand...
hahahaha the rest of us are in the 21st century
 
From at least 10 years ago there is a limited use for traditional fuel senders as the fuel flow from the engine is spot on on from my own experience on Yamaha and Suzuki and soon i will know if Hondas are the same (what i guess)
The only reason for tank fuel senders - independently if sending analog signals to a traditional gauge or have a NMEA2000 interface -

is to advert boat owner that fuel level is lower than the calculated value.
This would happen only in two conditions:
a) fuel got siphoned out
b) fuel tank is leaking massive amount of fuel in the bilge (what would be smelly and pumped out, or explode)

I will replace now the two fuel senders i have as i already have them working and they are cheap (35$ each) but fuel theft would be very unlikely in a slip so i could use only calculated fuel level.That worked for many years on my Venture 34 and from 2016 i use only calculated fuel level on all my boats and it was always spot on and i consider the 1-2% difference when refueling as error when filling up.

@Cedarman Did you solved something?
You need to verify where the signal for fuel gauges on the HDS9 come from, either tank senders or calculated fuel flow, you should be able to see that in a setting on your HDS9 and/or on the Mercury gauge.
Once you have found the fuel gauges you can pump out the tank with bad fuel - whatever that means and you may explain that - and then install a new fuel sender if this is desired or just use the old again to close the hole.
I have the feeling that your knowledge is limited so i suggest you to get a boat tech to do that as work on the fuel tank has to be done correctly as error can lead to very unpleasant experiences and hey may can find the problem why fuel level does not show up anymore .

Chris
 
Sardinia306Canyon said:
From at least 10 years ago there is a limited use for traditional fuel senders as the fuel flow from the engine is spot on on from my own experience on Yamaha and Suzuki and soon i will know if Hondas are the same (what i guess)
The only reason for tank fuel senders - independently if sending analog signals to a traditional gauge or have a NMEA2000 interface -

is to advert boat owner that fuel level is lower than the calculated value.
This would happen only in two conditions:
a) fuel got siphoned out
b) fuel tank is leaking massive amount of fuel in the bilge (what would be smelly and pumped out, or explode)
Click to expand...
C). You forgot to reset the Trip and reset the fuel to full or enter the added amount of fuel
D). You accidentally reset the fuel
E) you accidentally reset the Trip
 
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