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Smartcraft gauges and Fuel Sender

Hi All,

I recently bought a boat with a 150 merc fourstroke and smart craft gauges. Everything works fine except the fuel gauge, it always wants to read 100% full. I have checked the sender and went so far as to buy a new one but the ohm readings are the same as the old one so I figure it’s ok. I checked the wiring and replaced a short section so have some confidence in the wiring. I reset the gauges and made sure the tank size was correct but still ‘creeps’ up to full every time. The tank is about 1/8th full.

the dealer told me just to take some spare fuel with me!!

How do I get this fuel gauge working ?

thanks
 
OK..... The fuel gauge wires go from the sender to the (usually) 8 pin harness plug on the engine. The plug contains a few sets of wires for different senders... There is also a ground wire(orange/black) in this plug, you cannot use this ground for the fuel tank. It is a ground for the 5volt reference and the fuel tank has a 12v ground. What I do is, run a ground from the fuel Sender right back to the engine block ground.

So, make sure you are using Pink/Black for the sender positive. Ground the sender negative to the engine and do not use the Orange/black 5volt ground for anything.
 
Hey Chris, thanks mate for the response. You are spot on, I have traced the wires back from the sender to the 8 pin harness plug and the pink black is correct. The neutral runs to the negative terminal on the battery, which would have the same result as connecting it to the engine block ground. Right ?

the sender is a vdo float type that has a resistance reading of 3ohms empty and 200ish when full. Regardless of the float position my gauges always seem to read full, unless I unplug the sender and then the gauge slowly goes down to zero. When I plug it in up it goes to full ! It’s driving me crazy !
 
I would use a Wema fuel sender. They seem to work the best. The only time I had an issue with smartcraft not reading correctly after installing a Wema/Reed style sender was a bad harness at the gauge.

The reason I ground to the engine, it's close to the source where the 5volt reference is generated. The engine block is a nice clean ground for 5v reference no chance of stray 12v. The Orange/Black wire should not be used as a ground for anything, unless you have a plastic fuel tank.


wema-tank-level-guages-40l-s5-e225-__67437.1521721371.jpg
 
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Thanks Chris, I have placed a phone call to the installer to find out if it was ever working correctly before I blow more money on a new fuel sender. It was set up by a merc dealer so I can’t believe they would use an non compatible fuel sender that didn’t work. Pretty confident I have the wiring correct.

when I return the new sender I bought (just to compare with the installed one) I’ll ask them if they have a WEMA. If they do I’ll get just to check, provided I can return it.

let you know !
 
Sounds to me like your current sender follows the 'European standard'...the few smartcraft installations I've upgraded have all used the 'American standard' piece parts....
 
Ok thanks guys, problem solved. It’s a mystery why you would repower but not make sure that the fuel sender is correct and the fuel gauge works !!! But that’s what happened they used the wrong fuel sender and the ohm measurements were back the front. A new wema unit and it’s ok.

Also disappointing that the mercury dealer I went to couldn’t work this out...
 
Hi. I have similar problems on a boat i just bought. The fuel gauge goes the wrong way. My engine is a mercury verado 250 xl from 2017 and the gauge is a sc 1000. I haven’t had time yet to crawl down and check what kind of floater is installed, but it seems the ohms go the wrong way. Can anyone tell me if i should install a 0-180 (or 190) or a 240-30 ohm unit.
 
Hi again.
I managed to take a pic of my sender. It is a wema 240-30 ohm. And still the gauge shows all in reverse. Can it be that the motor or gauge system is sdapted to european standard(0-180ohm)?
And/or can it be switched from somewhere?
Id would be stupid to buy a new sender if the system could be switchable…
 
Hi again.
I managed to take a pic of my sender. It is a wema 240-30 ohm. And still the gauge shows all in reverse. Can it be that the motor or gauge system is sdapted to european standard(0-180ohm)?
And/or can it be switched from somewhere?
Id would be stupid to buy a new sender if the system could be switchable…
 

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