fuel gauge not working now

[boatman37]

Not sure if this should go here or electrical or Mercruiser...lol. So had to drain some fuel from my tank and pulled the sending unit to get a hose in there. There are 2 wires attached to the sending unit (red and yellow). After putting the sending unit back in now my gauge isn't working. It is sitting at about 1/4" below E and the tank is about 90% full. I checked the voltage at the unit with the key on and get 9.7 volts. Or should I be checking ohms? I can't find any fuses anywhere in the boat, just breakers.

Is it possible the float got flipped over inside the tank and is now reading upside down? I couldn't get the whole float out as the float itself was too big to get through the hole so I just moved it off to the side when I had the hose in there.

Thoughts? Boat is a 2006 Crownline 250CR

 

[GA_Boater]

The float fit in the hole after the tank was built, so it can come out the same hole. It takes some twisting and turning to get it out. No, it didn't get turned upside down.

Did you put the sender in the same orientation? If the sender is rotated one hole, the float may be hitting the side of the tank and can't raise.

 

[boatman37]

I assumed it went in that hole at some point...lol. Just that it won't come out now and I don't want to force or break it. My step-son actually took it apart and put it back together but he took a picture before he took it apart and it was put back together in the same orientation.

Seems electrical to me since it is reading about 1/4" below E. Seems like it's the lowest setting it can go to. Not sure how any wires could have been broke in the process though. And can't get the dash piece apart to get to the back of the gauge. There are 2 screws. We pulled those but there must be clips that hold it in place and we can't get it off so no way to get to the back of the gauge without getting that panel out.

 

[GA_Boater]

Was it working before you pulled the sender out?

 

[boatman37]

Was it working before you pulled the sender out?

yep. and was accurate. just took the 6 or so screws out and disconnected the 2 wires. didn't pull the sending unit the whole way out, just out far enough to get a siphon hose in there

 

[GA_Boater]

Then why are you fiddlin' with the gauge?

Take out the 5 screws and carefully lift the sender and make sure the float arm is parallel to the long tank sides.

 

[boatman37]

I was going to check continuity from the sender to the gauge. And wondered if there might be a fuse behind the gauges.

I took the sending unit out again today and can't see anything wrong. The sender wire that attaches to the center of the unit makes a 90* angle coming out of the conduit so I was wondering if that wire might have cracked or something by messing with it.

 

[Chris1956]

That sender should have a good ground (usually black) and the sender wire (usually pink). The pink wire should be on the non-grounded connector.

I would ohm the ground wire to the battery negative terminal. Resistance should be futile (actually zero).

 

[boatman37]

There is a pink wire and a yellow wire. The yellow goes to the ground and has a spade connector. The pink wire goes to the sender post in the center of the unit with a ring terminal so these can't be mixed up.

Will check and verify that ground is good. Planning on dropping it in the water tomorrow morning so probably won't mess with it again till next weekend. By the time we get the dock all set up then maybe go out for our first cruise of the year doubt I get to it tomorrow. I know a full tank lasts me a few weeks so we will be good for awhile but want to try to have it fixed for next weekend.

 

[Fed]

Pegging to below zero indicates an open circuit, short a wire between the terminals on the sender and see if the gauge pegs to full.
If it pegs to full you have an open circuit in the sender.

 

[boatman37]

Thanks for that!

 

[boatman37]

So did some more checking today. The ground is confirmed good so not that. I shorted the sender wire to ground and the gauge moved up so from what I read that means the gauge and sender wire are both good. That only leaves the sending unit? If I use an ohmmeter across the ground and sender post I get an open circuit. Shouldn't I get a resistance reading that moves as the float moves?

 

[Chris1956]

yes you should get a resistance reading from the sender. Maybe you broke it when you took it partially out? Anyway it is time to remove it and inspect, fix or replace it.

 

[boatman37]

So even removed on a bench they should have an ohm reading? With no power connected to it? My step-son removed it so not sure if he might have hit something or twisted something? I had it out today and got it completely out. Looks pretty simple.

Kinda ruled out everything else I think.

Looks like mine is a Rochester. My part number is 8341-7015 3805. According to this site this is the exact replacement? https://liquidlevels.net/products/r...or-8341-7000-9341-7000-9341-r7000-fuel-sender

 

[Fed]

The proper resistance readings are in the picture I put up.

 

[Silvertip]

Resistance of the fuel sender is measured without power connected because power is provided by the battery in the ohmmeter. Resistance should cover the range of 33 to 240 ohms as you swing the float arm through it's travel. What you need to look at carefully is the very thin, flat conductor beneath the center (insulated) connector on the sender and where it connects to the resistor. If the nut on the terminal was tightened to the point where the terminal rotated, that thin ribbon conductor can contact the metal support and be broken or shorted.

 

[boatman37]

Thanks. I was looking at that 'ribbon' connector today. It seemed good but who knows.

I'll look at that chart again but seems if I get an open connection reading on my ohm meter then there is a problem with the sender?