Old as Dirt!
Join Date: Nov 2008
Location: Tampa Bay Area
Thanked 132 Times in 125 Posts
Rep Power: 8
The fuel gage sending unit on the First 42 is located on the port side of the fuel tank above and aft of the water-lift muffler. Unfortunately, it is very difficult to access as the green ribbed ventilation ducts--which if still the originals are quite stiff--cover the sender and there is only a small access hole to the muffler space through the bulk-head between the port quarter cabin and the engine/fuel tank space. The access hole is below the panel that supports the cushion at the aft end of the berth, aft of the compartment where the hot-water heater and pressure water system are normally located. (I know this as I just went through replacing the water lift muffler and the exhaust hose on our 1986 First 42.)
There is no physical way to remove the fuel tank from the boat without first removing the engine. You must also gain access to the tabs at the aft end of the tank that are bolted to the stringers (port) and bulk-head between the sail locker and engine/fuel-tank space (on the starboard side). To reach to port aft tab you will have to remove the exhaust hose--a seriously major surgery--and the ventilator ducts, which will likely rip apart (as did mine) when you try to extract them as they have to make a sharp turn on the aft port side of the tank to be extracted through the space between the corner of the tank and the cockpit drain pipe from the bottom of the life-raft revetment to the hull. That is major surgery for little gain.
In our case, we enlarged the access hole under the quarter cabin berth by very carefully cutting--horizontally--through the bulk-head just below the cleat that is screwed to the bulk-head (to support the aft end of the berth) and then vertically down to the hull liner. You must be very careful doing so as all of the wiring for the instrument panel as well as the hose for the bilge pump also runs through this space. By opening it up, however, you gain better access to the muffler and the side of the tank where the fuel sending unit is located. Before doing any of this I suggest you see if you can reach through the access hole and find the sending unit by feel. There are two wires to the sender (which is a triangular shaped device) that can be fairly easily dislodged which may be the cause of your fuel gage not working. One goes to a very small ground post in the center of the body of the sender and the second goes to a post with a thumb-screw nut on the bottom rear side. It doesn't seem to matter which wire goes to which post.
For what it's worth I would not go through the brain damage of the foregoing for the sake of the fuel gage alone. The 4-108 uses about 9/10ths gallon per hour on average and I'd simply keep track of my usage as the gage is fairly inaccurate anyway and only gives a rough indication of the fuel level. Further, note that representations to the contrary not withstanding, the tank does not hold 40 gallons but only 37--as carefully measured and determined on another friend's boat.
I can give you some added information in real time if you PM me with your phone number.
"It is not so much for its beauty that the sea makes a claim upon men's hearts, as for that subtle something, that quality of air, that emanation from the waves, that so wonderfully renews a weary spirit."