Fuel Sender Unit

[Rob Peters]

2 hours ago, jft69z said:

The sending unit should have mechanical stops built right on the rheostat case to limit travel. It should never get to the point where it hits the top of the gas tank.

If the top of the float exceeds the plane of the mounting flange when you move it to 'full' position, your float arm is bent out of shape.

Joe, so what you are saying, that would account for the full to half full reading on the gauge would take longer than the 1/2 full to empty would take.  So what you are also saying is with a full tank the float will never reach the top of the tank, right?  Also since, with an empty tank the float would rest on the bottom of the tank and if you set the tank at the proper angle, the same angle it would sit mounted on the car and if that is true, with the fuel sender installed into the tank and the tank sitting at the proper angle, the ohm reading should be at around "0" (zero) ohms.  

rob

[jft69z]

The sending unit has stops built in to limit the travel (red circles). If the float is higher than the flange at the top, it may hit the top of the tank. There's usually a bit of an air pocket up there though, so it may be ok (the mounting surface is usually a bit below the top of the tank, so there is a little room for float travel). 

You can also measure from the flange down on the sending unit, and also do the same on the tank to see if the float would hit bottom. Realistically though, if the float is sitting on the bottom when you install it on the empty tank, the ohm reading will likely be greater than zero. 

All this tilting the tank, etc, is overkill. It's a simple float switch. Install it in the empty tank, should read zero ohms, flip the tank over, it should read 90 ohms if you're concerned it's hitting the top of the tank (or whatever value you measured when the sending unit was on the bench, sometimes it may read 2-89 ohms, or 1-91 ohms, etc).

For the record, I've never had to bend the arm on a sending unit. Unless the thing was mangled during shipping, it should be good.

I'm not sure this is a Monte sending unit, I pulled it from the pile of them in the attic. I tend to save old ones in case I need to modify one, etc. It's for reference only.

 

 

 

[cny first gen 71]

I do believe I'm going to order another new one before I do it again to be on the safe side.

[MGD72Monte]

Hey Rob, rather coincidentally I just finished a repair on a sending unit, not sure if this would help but I started a thread, link is below.  Cheers

 

[Scott S.]

Road salt is just natures way of telling us NOT to drive our Montes in the winter........ The risks are just way to high.