[Jaseun1]

Hi guys,

My truck fuel guage has apparently stopped working accurately. It indicates full all the way until I hit about 10 gallons left on my 40 gallon tank. It never shows empty. When the truck is off the guage will go all the way down so I guess that eliminates the indicator itself. Can anyone tell me what the next move might be? I plan to get under the truck and wiggle the connector on top of the tank when it stops raining here. Besides that is there a standard way to measure resistance on the fuel sending unit? Thanks -Jason

 

[techkdb]

Whats the history of the trouble? First time it happened? The unit in the tank can sometimes stick/freeze in one position. When you think its stuck place wood block against the tank and strike it with a hammer. It might vibrate loose. Report back.

 

[Jaseun1]

It happened over the winter when it was REAL cold. I ran out of fuel while trusting the guage and now use my trip meter to know when to fill up. The needle will come down to about 1/2 indicated when the tank is empty. That's how i discovered this problem.

I don't think the float is stuck or the needle might not ever move at all. But a block of wood and a hammmer has solved MANY problems with my toys over the years hahah. I'll give that a try when the ground dries out. Thanks -Jason

 

[SS317]

When did you do your tank mods? Could have not gotten something tight in there and it has vibrated loose enough to mess with things.... just a thought.

 

[klhansen]

Besides that is there a standard way to measure resistance on the fuel sending unit? Thanks -Jason

The fuel sending unit (when working correctly) has a resistance of 160 ohms full and 15 ohms empty. So you might just have a high resistance connection somewhere in the wiring.

If you unplug the connector, the gauge should go to full (infinite resistance).

BTW, I just use a big rubber mallet to whang on the tank when the float sticks. Doesn't always work though

, and I've wound up dropping the tank to get the float un-stuck.

Good luck.

 

[Jaseun1]

When did you do your tank mods? Could have not gotten something tight in there and it has vibrated loose enough to mess with things.... just a thought.

Tank mods were done a ways ago, 2001/2 I think? not that that isn't a possibility. Well the good news is that I have dropped the tank before several times and it's old hat by now :lol:. I'm gonna try to measure it first. I almost hope it's something in the sending unit because after that we're into the computer and then I'm lost :SM130:. -Jason

ps thanks for all the help guys! This site is an invaluable source of information.

 

[firemediceric]

Check my posts. I had the same problem but got it fixed with Klhansen's help

 

[Jaseun1]

update

I have the tank out and the sender unit taken apart. I can't get a stable resistance reading on the unit. It seems to jump all over the place. There is a bit of rust on the components. It also looks like the resistor board is worn down pretty good. Can anyone help me identify this sending unit with a ford part number? I've hit nearly all the online sites and most show a diagram of an in tank fuel pump (mine is frame mounted).

Here are some photos:

 

[lance1955]

Check over at rockauto.com They have the ford part numbers listed. Just brace yourself for the price !

 

[klhansen]

Good photos. :thumbsup:

The bad news is that Ford most likely doesn't sell the sending unit separately. You'll have to buy the whole fuel pickup unit if you get it from Ford. It might be worthwhile cruising the junkyards for a replacement unit.

 

[Jordan72]

Im having this same problem... any updates?

 

[lance1955]

So I was looking at the pictures again. I wonder if you bought a sending unit for a 1993 mustang and robed the sending unit off of it and attach it to the one you have. I guess for 50 bucks it would be worth a try? I compared the picture you took and blew it up and the appear aside from color to be the same less the metal clips it looks like your is held together with. I guess if you took the white box off and swapped your floats rod it should work, in theory. Dont know it maybe an idea the ohm reading is the same 15-160Ohm so I would think it should work. Here the link 1993 Ford Mustang Fuel Sending Unit