Location of sending unit on gas tank

[ethelwright]

Last year I bought a 1987 Grew 168 BR with an 80 hp merc. The boat has the gas tank built right under the floor of the boat . When I bought the boat(used from a dealer ) I was told it was "as is" and the sending unit did not work properly . They told me at the dealer that to replace the sending unit would be a $1000.00 job as the floor had to be pulled up to replace the sending unit . To date I have been keeping the fuel tank filled and carrying extra gas to be safe . Yesterday I was on the boat with my brother in law and we got looking at a small 10 inch diameter circular hatch on the floor of the boat . This small hatch sits over the gas tank and in the top of the tank is a circular thing with 2 or 3 wires attached to it. Could this be the mysterious sending unit ?Would it be hard to replace if this is the access point ? Is the dealer trying to rip me off ? I am not only a rookie to boating but I am also a female . I will also be running this by the guys at the marina where I dock my boat as they have been very helpful to me . Can anyone give me some feedback ? Thanks

 

[Boomyal]

Re: Location of sending unit on gas tank

You got told a tall tall tale. What you describe is undoubtedly the sending unit. It should be in close proximity to the fill neck, the air vent fitting and the pickup fitting but even if not, that's the culprit. Just be sure that the tank is not full and the boat is level before you remove it. No need to check with the marina people, just unscrew it and rip it out. No manufacturer would bury the access to the sending unit.<br /><br />ps, I would check for voltage, with key on, before you remove it. If there is no voltage to the sending unit it will not work.

 

[ThomWV]

Re: Location of sending unit on gas tank

The sending unit will be round, about 3" in diameter and it will probably have 5 screws holding it in place. There will be two wires going to it, one of them should be pink and the other should be black, but don't place bets on the wire colors. There will be a center terminal sticking right up out of the middle of it, that is the one the pink (sender) wire should be attached to. There is usually a flat quarter-inch tab to which the black wire would be attached by a spade connector, if it were not for the fact that the thing is probably rotted off of there by now. The is the ground wire. Oh, but the tank should still be grounded separately (I'm assuming its an aluminum or steel tank) to the ground system and also connected to the tank fill by a bonding wire.<br /><br />These two wires to to the guage. At the back of the guage there will be three terminals. One will have a "S" next to it and it connects to the pink wire that has the cetner pole fromthe sender on the other end. The next terminal on the back of the guage has a "G" next to it and it gets the ground wire that is attached to the tank. There will be a third wire going to the guage, this one is the power wire.<br /><br />There is no power going to the sender through the pink or black wires. It works like this; the guage is really just an ohmmeter (measures resistance) and the sender is really just a variable resistor with a float on an arm that rises and falls with the level of the fuel and that arm rising or falling controls the resistance in the line. Sender's rarely go bad. The wires between the sender and the guage go bad from corrosion all the time, and usually on the tank end. Guages go bad sometimes, but not as frequently as wires.<br /><br />Take a look at the fitting on the tank end of that black wire. I'll bet its a neat little blob of grandular green crap that doesn't even remotely resemble an electrical fitting. That's almost always the problem when they first quit.<br /><br />Thom