Testing a front fuel sending unit that reads empty

baby g

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Hi everyone,

I have a 93 F240 4x4 7.3 NA, and I'm trying to figure out how to diagnose a fuel gauge problem that I think is related to the fuel sender.

With the selector gauge set to rear, my gauge reads full and drops normally as I consume fuel in my rear tank.
With the selector gauge set to front, the gauge reads empty no matter how much fuel is in the tank.
I'm fairly confident my selector valve and switch are working because with the front tank selected, I drove until the engine started to sputter/run out of fuel. I switched to the rear and the sputtering/stalling stopped, suggesting to me that the valve did its job.

So far I've checked the resistance of the front sending unit, which is sorta tricky (getting the voltmeter leads to stay put is hard), but I believe it reads 15 ohms. Is there a definitive way to test if the sending unit is bad, or maybe it has a bad connection, without dropping the tank? Would the gauge read empty due to some other cause other than the bad fuel sender?

Thanks for the help!
 

Clb

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Never been done....












LOL Read the stickies. Then do a search.
There are four other threads on this I believe...
 

baby g

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I definitely did a search, but most of those posts are for gauges that are pegged at full, couldn't find an answer to this specific problem. I know how annoying it is to see reposts, but even just a link to a post on this forum would be helpful.
 

Clb

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I bumped what I have bookmarked for tank issues. Mos say pegged is grounds
Empty is sender
 

baby g

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Great I see your bumps. Thanks for the help. If someone stumbles across this in the future, here are the links to the threads Clb referred me to:


I'll report back here when I figure out what the issue is
 

Clb

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Fwiw
My front tank reads e always.
Draggin my feet doing it under the bed, as mentioned here on obn.

The trick used at stealership was loosen pass side bed bolts all the way, pull drivers side bolts out and lift bed from the side and prop it up.
 

Rdnck84_03

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If it always reads empty it is most likely a hole in the float. That is fairly common on 80 through 97 trucks. O'Reilly used to sell just the float, went a couple weeks ago to get one and they couldn't find it without buying the entire sender. Not sure if they stopped carrying it or the kid I was dealing with just didn't know how to find it.
 
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Old Goat

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Black dawg

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If it always reads empty it is most likely a hole in the float. That is fairly common on 80 through 97 trucks. O'Reilly used to sell just the float, went a couple weeks ago to get one and they couldn't find it without buying the entire sender. Not sure if they stopped carrying it or the kid I was dealing with just didn't know how to find it.
Or missing float. It is funny how many times I see this.
 

Rdnck84_03

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I havent run across that one yet, geuss that makes for a good head scratcher wondering wth the last guy in there was thinking. Mine were always flooded sitting on the bottom.
 

baby g

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Hey all, thanks for the replies! I'll try the float first, hopefully that's all that's wrong. The fact that I'm getting some resistance in the range of empty on the sender seems to me that the resistor inside the sender is working.

For anyone in the future with a 1993 Ford F 250 7.3 IDI, here's the electrical diagram for the sender and the selector valve:

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Clb

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Hurry up with my beta testing....
I don't even know if I want to pull the effort out of the kitty to fix mine...
:cheers:
 

Clb

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baaaack from the dead....
I'm biting thee Bullet, Pulled the bed mounted genset and 5er hitch, toolbox ect. to go after the sender.
been after it since sunrise.
who has a cheat sheet on how the plug comes out, and how them dang disconnects come apart?
I will hunt in the am but it is Miller Time now.
 
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hacked89

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baaaack from the dead....
I'm biting thee Bullet, Pulled the bed mounted genset and 5er hitch, toolbox ect. to go after the sender.
been after it since sunrise.
who has a cheat sheet on hoe the plug comes out, and how them dang disconnects come apart?
I will hunt in the am but it is Miller Time now.
Flathead pop and remove clip push forward then back. Any wiring questions just let me know.
 

Jesus Freak

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baaaack from the dead....
I'm biting thee Bullet, Pulled the bed mounted genset and 5er hitch, toolbox ect. to go after the sender.
been after it since sunrise.
who has a cheat sheet on hoe the plug comes out, and how them dang disconnects come apart?
I will hunt in the am but it is Miller Time now.

Flathead pop and remove clip push forward then back. Any wiring questions just let me know.
There's also a certain facial expression you have to make, but if I posted it it would never get moderator approval. Yelling like Stallone or Swarzeneger is another trick to getting the hoses off but you have to yell loud enough that the police show up.
 

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