Is my sending unit working?

pos1

Recruit
Joined
Aug 13, 2008
Messages
3
2003 Crestliner 1600 tiller, 40hp Mercury 4-stroke

last summer my motor stopped running. After a lot of debugging I added about 2 gallons of gas and it started and ran perfectly. Gauge showed 1/2 tank. Ran fine the remainder of the summer. Thought sending unit.

just digging into it. Tested gauge and it works.

I have the sending unit out of the tank.

the gauge starts at 1/2 tank when the float is all the way at the bottom. It doesn’t start to move until I hit about 1/2 way up. At that point it moves from 1/2 tank to full.

so here’s my dumb question. Does it work any differently in gas than me moving it manually? is it obviously broken considering it never goes below 1/2 tank no matter where the float is?
 

lmuss53

Lieutenant Junior Grade
Joined
Sep 9, 2008
Messages
1,227
Put your meter on the sending unit wires and check it for resistance all the way thru it's travel range. It should change in a relatively consistent manner from top to bottom. it should be pretty high at one point and low at the other.

When there is no power to the gauge does it go to empty?
 

ajgraz

Lieutenant Commander
Joined
Mar 1, 2010
Messages
1,858
Fuel senders do go bad, on boats and in cars! Fuel is some nasty stuff.

I strongly recommend going to a reed sender when you replace the existing one. So much more robust.
 
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