fuel guage

chipman

Seaman Apprentice
Joined
Sep 27, 2008
Messages
35
hello everyone

my fuel guage is not working, i have read all threads on this site and still cant figure this out, please help!!!!


i have regrounded the sending unit on both fuel tanks, regrounded fuel guage, i am getting full power to pos connection on gauge "with key on", i am getting about 4 volts from the guage on the sending wire.

when i ground the sender wire it shows full on either tank. i bypassed the fuel tank selecter switch still the same. i used a long wire from tank sender to gauge and shows full when tank is empty.

i puled the sending unit from both tanks and they are able to move and are not hitting baffle is tank.

is my gauge bad, or are my sending units bad? i dont think it is very likely both sending units would be bad.

please help, this ig getting frustrating and i don't want to spend money buying un-nessasary parts.
 

Al Kungel

Petty Officer 2nd Class
Joined
Jul 9, 2004
Messages
144
Re: fuel guage

Just very recently I had to replace the voltage gauge on my boat. I have Faria gauges on my boat. I went to the Faria website and found instructions on how to check whether the gauge was faulty - it ended up being the gauge. Faria has a lifetime warranty on their gauges.

I would check with the manufacturer of the gauge, they may be of some help.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: fuel guage

If the gauge moved to full, it's working. When you grounded the sender, how did you do it and where did you ground it to? Did you actually measure the resistance of each sender when you had them out. Should read 33 - 240 ohms as you move the float arm up and down. 1/2 tank should read about 105 ohms give or take a little. Resistance must be measured with the sender wire disconnected.
 

chipman

Seaman Apprentice
Joined
Sep 27, 2008
Messages
35
Re: fuel guage

i will cheack the manufacturer to see if that helps, i grounded the sender wire to the ground on the guage. and i was unable to check the senders, i have a cheap multi-meter and it has an ohm setting but really only measures continuity. so i guess my next step is to find a good meter so i can measure these. i just find it hard to beleve both would be bad, i dont know if they went out at same time or at different time's they were not working when i bought the boat. this is on a 1982 ranger bass boat 17 foot.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: fuel guage

There is no need to run a ground wire from the sender all the way forward to the ground on the gauge. The main ground point on any boat is the negative terminal on the battery. Why not connect it there. Since you may have a ground issue at the gauge, running ground wires up there proved nothing -- you still could have a ground problem. Likewise the gauge ground does not have to have a wire running all the way back to the battery because ground is already present at the helm. So the safest and most effective sender ground is run a separate wire from the shell on each sender directly to the negative post on the battery. There should also be a static ground wire from each fuel fitting. Ensure the tank selector switch is working by simply jumping between the center terminal (the one going to the "S" terminal on the gauge) and either of the other two terminals. Make sure the gauge has a good ground (connect it to the ground terminal on any other gauge) or to the ground buss on the fuse/breaker panel. It needs +12V when the key is on. If you have functioning senders the system will work. Miss any one of the elements and it won't work.
 

chipman

Seaman Apprentice
Joined
Sep 27, 2008
Messages
35
Re: fuel guage

to clarify i did not run ground from batt to gauge, i ran pos wire from sending unit on fuel tank to guage to varify sender wire was not grounded.

i was working on it today and ran into something else. i removed the guage so i could work on it better, when i remove the positive wire and the sender wire from the back of guage, i loose all power at the key, i still have to do more checking but it acts like ignition system may be grounded through the sender wire. it started getting dark so i quit i will look at it again tomorrow, any thoughts on how this can happen??
what wires should come from ignition, where should they connect?

is there any wireing diagrams out there for the entire boat, i think this would be helpfull, it seams i have alot more wireing problems than i thought and i may need to trace the wireing to all guages, because with this problem i also have a trim guage not working, and the lorance depth finder only works part time.

thanks for the advice thus far, but it seems i may have along way to go...
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: fuel guage

Removing power from the gauge should not kill power to the key switch because that's where the gauge should be getting its power FROM, not TO!
Here is a picture of what instrument panel wiring looks like.

InstrumentPanelWiring.jpg


Here is the back of a typical ignition switch (two stroke outboard). The "B" terminal gets +12V from the battery through the engine harness. The "A" (accessory) terminal is what feeds the gauges and any of the other stuff on your boat that is energized when the key is on. This terminal should be feeding the gauges -- not the other way around.

OutboardIgnitionSwitch.jpg
 

chipman

Seaman Apprentice
Joined
Sep 27, 2008
Messages
35
Re: fuel guage

Great that diagram should help, i will start tracing wires to find the problem, i've been planing to redo the wireing anyway i have this ball of wireing under the helm that you would not beleive. thanks for all the help i will keep you posted on the progress, with my schedule this should take about a week.
 

chipman

Seaman Apprentice
Joined
Sep 27, 2008
Messages
35
Re: fuel guage

i started looking through the wireing, all wireing is hooked up right, so i must have bad senders in the fuel tanks, i will have to get a good multi-meter to check them.

by the way, the reason i lost power to the key. i blew the ignition fuse located on the motor, somehow i must have shorted a wire when i unhooked it.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: fuel guage

The wiring cannot be right if you removed +12V from the gauge and you lost power to the key switch! Using a voltmeter, you need to check for +12V at the accessory "A" terminal on the key switch with the key ON. Since you removed the gauge, you probably interrupted the ground to the rest of the instruments. However, there are two ways power and ground on the gauges can be daisy chained. The wire coming into the gauge can be inserted into the ring terminal along with the wire going to the next gauge. If that's the case, the chain is not interrupted. If the wire going into the gauge is a separate wire from the wire going to the next gauge, then you did interrupt the +12V and ground feeds. I agree with you that it highly unlikely that both senders are bad. I do suspect you have a wiring issue but since we can't see your boat, you will need to approach this logically and not "shotgun" the problem. You can start by verifying the switch is working.
 

chipman

Seaman Apprentice
Joined
Sep 27, 2008
Messages
35
Re: fuel guage

I have a hard time explaining this problem, i see i kinda jumped around a little as i was troubleshooting and posting, let me try to clarify.

the reason i lost power to the key when i unhooked the guages was not from disconnecting the wires, when i turned the key on to check the voltage coming through the acessory wire to the guages "purple one" i shorted the wire somehow and blew the 20A fuse located on the motor.

after replacing fuse i turned on key and was getting 12v through the purple wire to the quages, i varified the ground was good with ohm meter, and gauge light that uses same ground works.

i am positive that i have 12v to guage, good ground, 12v to accessory when key is on, and i am getting almost 4v out at sender connection. both tanks are grounded to the battery,

when i hook up sender wire to senders in fuel tank it reads full, when i have sender out of tank so i can move it, guage shows full at any position when i move the float up and down. fuel guage acts like sender wire is connected to groung when it is hooked to either tank sender. i will be buying a better multi-meter when i get a chance to see what kind of resistance i have through tank senders.
if the guage is working, the tank senders are the only thing i can see that could be wrong.
the guage i am using is a medalion fuel guage, i went to there web site, but it was no help.

i hope this helps clear things up, let me know is something is not clear.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: fuel guage

If the gauge does not track movement of the float arm you have either a bad sender or the gauge is bad. So the simple test is to disconnect the sender wire either at the gauge or at the sender. Connect an ohm meter to the sender or sender wire and the other test lead to ground. Now move the float arm. If the ohm meter does not read 240 ohms (float down) or 33 ohms (float up) the sender is bad. If it does, then the gauge is probably bad but I'm really skeptical about that.
 

chipman

Seaman Apprentice
Joined
Sep 27, 2008
Messages
35
Re: fuel guage

thats what i thought, my next day off is monday, i will get a good ohm meter and check the senders. i will post what i find
 

chipman

Seaman Apprentice
Joined
Sep 27, 2008
Messages
35
Re: fuel guage

ok silvertip i think i found the problem, when i pulled the sender units out of the tanks they both measured 0 - 1 ohm so i thought they were bad.
i looked at the wire that connects to the bolt where the sender wire hooks to. there was a spot that was shorted, i moved it and now i read 33 - 38 when float up, and 180 - 190 when float down. it is raining here now so i cant go check them but i think i found the problem, i will let you know when i check them. thank you so much for the help.
 

chipman

Seaman Apprentice
Joined
Sep 27, 2008
Messages
35
Re: fuel guage

problem solved. it stoped raining long enouph to put senders back in tanks, one reads correct the other fluctuates a little and reads only 3/4 when guage is all the way up, but this is not a problem, i only need to know when im going to run out of gas and it reads correct when below 1/2, may have to replace when it goes bad but is good enouph for now. now its time to move on to the last problem with this boat, the trim guage..

thanks again for all the help:D:D
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: fuel guage

Thanks for the come-back. Most people don't bother so we never know whether they got the problem fixed. You learned something in this exercise. Whenever you see a terminal with an insulating bushing around it, and you are having electrical problems, inspect that bushing as very often it is out of place or deteriorated and as you found out, can cause a short. Anyway, glad you got it fixed.
 

chipman

Seaman Apprentice
Joined
Sep 27, 2008
Messages
35
Re: fuel guage

no problem giving you the follow-up, just glad this site was here, problem wasn't realy with the bushing, looked like nut on top of sending unit was over tightened and turned the bolt, which grounded it to bracket that holds float.

anyway without your help i would have started changing parts, and draining the bank account for no reason. thanks again and maybe we might meet up again when i have another problem with my boat.
 
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