Fuel Guage stays pegged without power, is it bad?

[merlin696]

Fuel Gauge stays pegged even when i shut the power off, It is on an 89 Sea Ray I/O Mercruiser

Is it a shot gauge?

IF the gauge is bad what would cause it to peg like that?

 

[foodfisher]

Re: Fuel Guage stays pegged without power, is it bad?

Pegged full or empty Stays pegged even after you've disconnected the power? I mean phisically removed the power and signal wires?

 

[glenn property of pam]

Re: Fuel Guage stays pegged without power, is it bad?

with wires removed. pegged full proberly means the needle has skipped the backstop or corroded inside. if the fuel needle was on full and it got jarred then the needle can skip the little pin and jam not worth the effort to repair unless its a special gauge.
pegged empty is proberly a electrical problem (silvertips has some real cool wiring prints he post one on fuel sender a few post ago).

 

[merlin696]

Re: Fuel Guage stays pegged without power, is it bad?

pegged full and with the key out (normally it pegged empty when you turn the key off), It got dark before I could yank the power or disconnect the gauge.

 

[foodfisher]

Re: Fuel Guage stays pegged without power, is it bad?

Reading full w/full tank = guage works switch doesn't. Gotta experiment more and bring back the results.

 

[merlin696]

Re: Fuel Guage stays pegged without power, is it bad?

its bout half tank in the boat, and when i say pegged I mean that sucker is ALL the way past full, and it doesn't twitch, flinch, nothing when you cycle power on off, also cant get it to go back down tapping it.... I can also follow up with yesterday on the lake it wasn't working at all but opposite, it stayed on E, then towards the end of the day it came back to life, today during garbage clean out from the trip and i turned the key started the engine then after a long while it twitched a couple of times and now its stuck on super full!!

 

[foodfisher]

Re: Fuel Guage stays pegged without power, is it bad?

Untill the electronic geniuses post, here's my story. My guage misbehaved when I first got my boat. While I had it apart for more reasons than this, I decided to see how the sender worked. Knew it was faulty. The swing arm that has the float on one end had a little spring loaded ballbearing on the other end. This ball bearing would move across wires stretched across it's arc. Whichever wire it was touching would register on the guage where it was at. Well my little ballbearing had frozen in place and when the float forced it across these little wires it ripped them from their roots. Wires pointing every whichway made the probs. similar to what you are expierencing.

 

[Silvertip]

Re: Fuel Guage stays pegged without power, is it bad?

It appears earlier in the day you had an intermittent problem where the gauge didn't work at all. What has apparently happened is that there was a loose connection on the gauge that allowed the "S" (sender) connection to short to the "I" (ignitiion) terminal. This pegs the gauge and is a MOMENTARY test of the system to determine if the gauge is working. A prolonged short like that can stick the gauge. It is also possible that the sender has been shorted to ground since zero ohms represents a full tank. Actually 33 ohms represents a full tank but so does zero. So - disconnect the sender wire from the sender. Measure resistance from the threaded post to ground. If it shows about 109 ohms (you said it had 1/2 tank of fuel) then the sender is ok. 109 ohms is about 1/2 tank. If it measures closer to zero then the sender is mucked up. With the wire disconnected, turn on the key. The gauge should should empty. If it still shows full there may still be a short at the gauge (S & I terminals). If not, the gauge is toast.

 

[merlin696]

Re: Fuel Guage stays pegged without power, is it bad?

well a small problem just got worse. So over the winter I had floor and stringers replaced, guess what I cant get to now...


I can see the wires running under the floor from the engine area, but there are 3 wires, the diagrams I have looked at only show 2

 

[Silvertip]

Re: Fuel Guage stays pegged without power, is it bad?

well a small problem just got worse. So over the winter I had floor and stringers replaced, guess what I cant get to now...


I can see the wires running under the floor from the engine area, but there are 3 wires, the diagrams I have looked at only show 2

The fuel sender wire is pink and is the only wire running from the tank up to the gauge. Have no idea what the other wires are for unless you tell us what color they are, where they come from and where they go to. Do the etest at the gauge with the sender wire disconnected. Same as doing it at the sender.

 

[merlin696]

Re: Fuel Guage stays pegged without power, is it bad?

after church... ill hop in and get more details now that its daylight...

im tryin but the damn sun is kickin my ***!

Nuf Said

 

[merlin696]

Re: Fuel Guage stays pegged without power, is it bad?

Dug this out of the photos I got when the repairs were being done, the 3 wires, 2 go to sender and 3rd goes to filling hose cover.

question do both wires screw on? I cant tell from the photo or does one just have the slide clip and the center pole bolts on?

 

[Silvertip]

Re: Fuel Guage stays pegged without power, is it bad?

The pink wire (the one that goes to the threaded post on the sneder) is the sender wire that goes up to the gauge ("S" terminal). The other two are grounding/bonding wires. The metal shell of the sender must be grounded to the negative terminal of the battery as does the one coming from the fuel filler neck. The gauge would work without that last connection, but it won't work without the sender shell being grounded to the negative terminal of the battery or to the engine block or whever you find ground in your boat.

 

[merlin696]

Re: Fuel Guage stays pegged without power, is it bad?

would the ground on the sender unit be threaded or could it "pull" somehow? if did, I have no way to get to it.. I can get to the filler neck, there is a plate cover over that. I think I may take my cell phone camera and see if I can take a pic down the length of the tank through that small hole and check to see if its connected.

If that does pan out and I can get a photo and everything is connected, can we say that odds are the gauge went bad?

 

[merlin696]

Re: Fuel Guage stays pegged without power, is it bad?

Dont know why I didnt just do this sooner, Called the Fiberglass guy who did the floor repair and he said just bring the boat down and he will cut out an access whole and put a panel over it. He said he would check the sender for me and then let me know from there what I needed to fix.


Thanks everyone for helping try to work this out.