Fuel Tank Senders

[oldtimer]

Hi guys, as a lot of you know I just purchased my 74 Tri Cabin mid Sept this year, and knew that it had some instrument gauge problems, mainly fuel tanks and oil gauges. The boat is hauled out and winterized now, so I removed the whole dash board and brought it home to do a bench test check on the gauges. A good friend of mine did the test with me and agrees all the gauges on my dash are working, so that leaves me to replace an oil sender, and then what seems to me to be the one big problem will be the fuel tank senders. I have access to both my tanks (round galvanized) thru removable floor panels. To say that I am quite nervous about working on opening up a gas tank with fuel in it is an understatement. Have done a lot of things, but never this. Seems to be a risky dangerous job. So first off, is there any way to check out the senders , or clean the terminals before removing them ? Maybe I would get lucky and find the problem there I know this job has to be done because you have to know how much fuel you have left. Is it a common thing for them to fail ? Another thing I noticed when doing my winterizing, is that there is a copper fuel line running from engine to engine up on the overhead at the aft end of the engine compartment. The line is a continuation of the line from each fuel tank, with a teed off line to each engine, before continuing the loop around to meet each other at a shutoff valve. The shutoff valve, is accessible just inside the hatchway into the transom between the two aft bunks. This shutoff valve is in the closed position now. Should it be open or ? Any help appreciated.

Oldtimer

[g36]

on a f32 which i had, the valve you are speaking of is a crossover valve and will allow the fuel to be drawn from either tank for the engines, a great thing to be able to switch if fuel problem comes up or other need.(i.e. generator used alot of fuel out of one tank etc) it would normally be run in the center postion so each engine draws off its own tank.

heres a easy way to check your senders
senders are about 240 ohms at low and 30 ohms at high (full).
If you disconnect the wire from the sender to the gauge the gauge should read empty. If you now take the wire from the gauge and ground it, the gauge should read full. If nothing happens or the readings are intermittent, you need to find where that wire connects at the gauge and do the same tests, no connection to the gauge and grounded. If the gauge doesn't react properly it is bad OR the battery connection is bad/intermittent. To check that you need to measure the voltage to the meter and wiggle things (connections) to see if it fluctuates. shouldnt be a big deal to change the sender if needed it just screws to the top of the tank and just have the new one prepared best you can and ventilate the area while working on it.
heres a link to help if needed
http://faria-instruments.com/site_manua ... Gauges.pdf

[oldtimer]

Many thanks g36, for the info on the fuel line, and a method to check out my fuel tanks. After reading your post, and checking the website you showed, I feel that I know how to check the fuel senders out now. I would like to do this check immediately on the tank senders, but unfortunately, it will have to wait now until spring time to check them out as my boat has been lifted up in its slip and lowered down and stored on timbers, lying from slip to slip. Once the boats are all up its not allowed to go on-board to do any projects, due to the insurance regulations.So I will print the info off and keep it in my owners book until spring. (And I hope that I find some fault in the wiring, because like I said, I am nervous about changing the senders.) Thanks again

Oldtimer

[rickalan35]

Hi Oldtimer - I'm driving a '74 Tricabin as well. Not too far away from you. I had the interior of both galvanized gas tanks removed (ugly job) and glassed (rotational moulded) about six years ago after having developing pin hole leaks. No leaking issues since this was done (knock on wood). But, the gas gauges have never worked since that time. I simply keep'em full of fuel, but that is a pain in the you know what. Maybe I can get to the bottom of this gauge problem now with the info from G6 and from yourself. Thanks for bringing it up.

[boatsnbars]

I just installed these sending units on my F-36. The are custom length so you have to measure the depth of your tanks. I pulled out the old sender, stuck a tape measure in and followed the instructions on the website. I reinstalled the old senders until the new ones arrived. They work great so far. Removing the old sending units is pretty ease if you have access to them. 5 screw and a gasket. The new ones came with gaskets but I reused the screws.


http://www.wemausa.com/

[oldtimer]

Hi rickalan35, interesting to hear how you replaced your tanks. Never heard of this process so far but will also keep your feedback on file with everybody else's. I have so much to do on my old girl, so I hope my tanks hold on for a few more years.
boatsnbars, thanks for the website in regards to replacing my senders. Good to know that they are available to buy, and If it turns out mine are bad, I will bite the bullet and start the process of replacing them next spring. I still dont look fwd to doing this job, but have heard a few of you guys doing it on this site.

Like I said, boats put away now, but I do remember looking down on the tanks, when checking out the senders, and seeing lots of green corrosion around the connections. Next spring I will first try and clean up the tank connections, and then try getting an ohms resistance reading as suggested by g36 for each sender, & see where it leads to. Thanks for the feedback guys, really helpful.

Oldtimer

[rickalan35]

Oldtimer - Where do you keep your Trojan docked?

I too, am looking forward to getting my fuel tank sender situation squared around (hopefully). I'm sort of concerned that the coating that was applied to the inside of the tanks has managed to cover the sender apparatus or some such thing.

In regard to the amount of future work you're anticipating, it seems like we're always working on these critters. I bought mine in 1998 and am pretty darn loyal to it. Have had a lot of fun.

[oldtimer]

rickalan35, we are keeping the boat on Lake Simcoe, south end, in a covered slip, to be close to home while working on it. All of our previous boating was up on Georgian Bay. When I get back to working on the problem come spring I will post how everything turns out. Take care.

Oldtimer

[Big D]

....both galvanized gas tanks removed.....the gas gauges have never worked since that time....

Did they ground the tanks again after they reinstalled them?

[rickalan35]

Hi Big D - I'm essentially a know-nothing when it comes to these fuel tank senders. If I remove what I assume to be the fuel tank sender access covers (port side in the floor of the cupboard under galley sink and on starboard side - inside the hinged second step down into the aft cabin) what am I to look for re: Ground Hook Up ?? Any advice appreciated. I know I can get the marina guys to take a look but if possible, I'll try to do it myself. My boat is now in covered storage but I have access year round.

Thanks in advance. Rick