WEMA Fuel Sending Unit

T

TUNAHUNTER197

Well-Known Member
Joined
Apr 10, 2013
Messages
102
Reaction score
31
Points
28
Location
San Jose, CA
Hey guys! My fuel sending units have been acting a little wierd, and I am unable to get a somewhat accurate reading on my gauge on how much fuel is in the tanks. Typically they only read accurately when the boat is on plane, so yesterday I removed the unit from my main tank and slid the float to the full position, and the gauge at the dash only had one bar blinking (stating it was almost empty). I cleaned the ground thinking it might help, and nope, nothing, blinking empty. Its a WEMA sensor ( http://www.wemausa.com/sensors/level-Fu ... HPFd_nF_Nu ). I even went the extra mile and filled up a 5 gallon bucket with water and let the float move towards the top in the water, and still a blinking empty reading at the gauge.

Any suggestions on how to tackle this one? I can purchase a new unit from WEMA, but don't want to if I don't have to. Yamaha gauges, boat is a 2000 265 express, if that helps. Thanks!
 
S

suzukidave

Well-Known Member
Joined
Sep 24, 2013
Messages
383
Reaction score
9
Points
18
disconnect the sender at the pigtail splices and put an ohmmeter on the two pigtail wires coming from the sender. you should see either 5-105 ohms or 30-240 ohms as you move the float up and down. if you see no continuity or some other ohm range then there is a broken wire or problem in the sender. unless you can see wire damage in the pigtails it is probably best to replace.

if you see the correct ohm range then you most likely have wire damage between the sender and your dash. you can verify this by reconnecting the sender then disconnecting the wires right at the instrument and doing the same test.
 
S

seasick

Well-Known Member
Joined
Aug 19, 2008
Messages
9,145
Reaction score
1,311
Points
113
Location
NYC
Also you can touch the sender lead to a good ground. Your fuel gauge should read full.
 
T

TUNAHUNTER197

Well-Known Member
Joined
Apr 10, 2013
Messages
102
Reaction score
31
Points
28
Location
San Jose, CA
Thanks guys! Dave, when you say pigtail that is the connection at the sending unit, not the gauge? Just want to confirm the right place to test continuity. Thanks again guys for the help. Would there be a reason I was getting the same reading, blinking empty, when I tested the AUX tank fuel sender as well? And I did flip the switch at the dash when testing the AUX and Main.
 
S

suzukidave

Well-Known Member
Joined
Sep 24, 2013
Messages
383
Reaction score
9
Points
18
pigtail at the sending unit.

but if you got it from both tanks i doubt it is the sender. more likely a bad connection at the gauge. your gauge may read empty when there is no connection at all.
 
T

TUNAHUNTER197

Well-Known Member
Joined
Apr 10, 2013
Messages
102
Reaction score
31
Points
28
Location
San Jose, CA
The gauge starts to move once I get on plane, but on the trailer it typically only reads low to empty. Last weekend filled the tank all the way, and the gauge only read half full when I got on plane. I'll check and clean the connections at the gauge since the connections at the sender looked good. Thanks again!
 
T

TUNAHUNTER197

Well-Known Member
Joined
Apr 10, 2013
Messages
102
Reaction score
31
Points
28
Location
San Jose, CA
Excuse the dirty tank picture, but my fuel sender has a green wire grounded to the tank. Does this look correct?
 

Attachments

  • image.jpg
    image.jpg
    139.6 KB · Views: 3,603
S

seasick

Well-Known Member
Joined
Aug 19, 2008
Messages
9,145
Reaction score
1,311
Points
113
Location
NYC
TUNAHUNTER197 said:
Excuse the dirty tank picture, but my fuel sender has a green wire grounded to the tank. Does this look correct?
Click to expand...
Yes but..
The tank itself should have a ground wire attached to it. The ground for the sender does no good if the tank isn't grounded properly.
The barrel connectors for the signal and ground leads should also be checked for corrosion and/or bad contact. Give them a look and a good pull to check for poor crimps.
Now unplug that pink wire and connect a wire from the battery negative terminal to the disconnected wire that goes to the helm. With the ignition on, the gauge should read full. Disconnect the wire (not connected to anything) and your gauge should go to empty.
On a separate note, is there a clamp or two missing from what looks like your pickup tube - fuel hose connection?
 
T

TUNAHUNTER197

Well-Known Member
Joined
Apr 10, 2013
Messages
102
Reaction score
31
Points
28
Location
San Jose, CA
This is great advice, and I will take it step by step Friday and hopefully get to the bottom of this issue. Last June I changed out all fuel lines and pickups, and this was the only picture that I had of the sending unit. As you can see the clamp is slid up the hose, but currently I have a hose clam and a zip tie securing the fuel lines to the pick-up. Good eye though!!
 
You must log in or register to reply here.