Fuel sender

Yep... as Bjorn says...

I remember a ground wire that attached to one of the 6 or 8 nuts that sealed the sending unit to the tank.

Sorry... butits been soooo long since I touched min I can't remember the details of how it was installed. I do remember reversing the wiring from the light and the guage and it didn't work right, and didn't hurt anything either.

You should be able to test the sending unit OUTSIDE the tank for all its functions BEFORE reinstalling it. Best that ya do... I used test clips...
 
I just don't see how the sender unit itself is grounded. There is no connection (that I see) between the sender and ground, the top of the sender yes, grounded via dedicated black wire to one of the hold down bolts but I see no connection between the sender circuits and the rest of the sender assembly, ie; no ground path. There's one in the diagram. There must be one. When I test I ground the top of the sender as if it were installed and get no response from gauge, if I run the ground straight to red/black side, reserve light comes on, if I run a ground straight to the rheostat side it pegs full. If I touch a ground somewhere in rheostat wires it reads the appropriate amount on the gauge. But nothing happens anywhere when I simply ground the top. I still suspect it is supposed to ground to the rod that holds everything through the sweepers cam, like it rubs the mounting bracket but.....I don't know.
fuelsender.jpg


If so I could solder in a better ground through the side of the plastic housing like:
fuelsenderwithground.jpg
 
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WOW... ya got me spinning...

I say NO...

The wiper needs to be isolated from ground as it transmits the modified voltatge from or to the resister.

Saying that... it may be a resistence TO ground... but in any case... the AXLE is NOT part of the electrical path.

I doubt if it was touching the case or not would make any difference... or should I say... SHOULD NOT make any difference. With all that rust or corrosion it may be conducting.

I would thing the WIPER MAY BE isolated from the axle also...

Ya know... I have never seen a sender in such bad shape either... and you PROVED the guage and low level light good... Maybe ya oughtta just get a NEW sending unit.. You deserve it.

(You can then stare and compare and possibly refurbish the old one and recoup some of the cost.)
 
I think I'm with Jeff on this one.

Although it is COMMON to apply voltage across the ends of a potentiometer and pick off a VOLTAGE on the wiper, I don't believe that is how the fuel gauge works. I believe the fuel gauge in the instrument panel measures current to ground through the rheostat in the sender. It looks to me (in Jeff's photo) as if there is a wire connected to the top end of the rheostat winding and if that is the case, the wiper would need to be grounded.

Ya know... I have never seen a sender in such bad shape either... and you PROVED the guage and low level light good... Maybe ya oughtta just get a NEW sending unit.. You deserve it.
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Couldn't agree more. Go buy yourself a new sender. We won't tell your wife.
 
I soldered in a wire as above and gauge works fine.
So with my new wire and ground on top of sender as it would be installed, I move the float arm and gauge reads as it should, reserve light comes on. I guess it is supposed to ground through there after all. The plastic housing was/is not very tight to the bracket and I swear it was'nt even attached as I drew it out of the tank. I know it looks bad but that's just the bracket the rheostat wires look fine and such. I'll run it for a while and if it fails I'll get a new one, it's easy to replace.
 
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ng_randolph said:
..... Go buy yourself a new sender. We won't tell your wife.
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You got me pegged already. See though, now I can brag about fixing it and "saving" $35 (to be spent on some more interesting X part.....
Seriously don't think this fix will last. It was hard to solder to that "button".
 
do not!

Buy the one on ebay for 65! You can buy one from Vic, IAP, basically anywhere for much cheaper.
 
simple

check the ground (-12V) .
Mine didn;t worked untill i have put a aditional ground wire on it , then it worked :)
 
The sender top/rod was grounded fine, it was the sender unit itself (the plastic housing that holds the works) that wasn't grounding well to the bracket/rod. The wire I added did the trick.
 
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Might want to check the other ground connections on your X while you're at this.. There are several ground stars (where the black wires meet a circular connector) to the chassis and the connectors. These can be a source of various "strange" electrical problems that can happen on the X.

Bernice

jvandyke said:
The sender top/rod was grounded fine, it was the sender unit itself wasn't grounding well to the bracket/rod. The wire I added did the trick.
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Got everything reassembled early this morning and well it was too late to play with it. The gauge worked!

Later that same day...
Added some gas, drove to station and added some more, gauge seems to function perfectly. (But I doubt it will last....)
 
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Chris St-Louis said:
Just for the future, a easy way to evacuate fuel from and injected X is disconnect the output of the fuel filter, stick a hose on it leading to a gas can. TUrn the key to on,remove the air filter and push the door lightly to engage the pump and use the pump to do the work.
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Thanks for that tip! Used it to steal some gas for my lawn mower today. Is it okay to pump out gallons worth at a time? Not sure if that continuous duty is any more strenuous on the pump than normal engine running.
 
I think it's always continuous duty isn't it? In FI? always pumping and pressurizing and returning to tank?
 
Yes, the pump pushes more fuel pressure than the engine can use - the regulator drops the pressure, and the rest goes back to the tank, for as long as the engine is running.
 
I should also confess my "fix" of adding another ground is only partially successful. The needle swings wildly giving a very vague sense of fuel level. I think the reserve warning light should still work but, not really "fixed". I need to get a new one.
 
when I did mine I just ebay'd any old fiat sender.. ripped it apart and used the wiper assembly on my own.. soldered and shrink wraped the wires.. it works perfectly.

the correct sender for the x was unobtainable and had a hefty price tag even if it was available,, the one i bought was for some non descript fiat and was brand new for $15.
 
I got tired of the swinging needle, it was really getting wild, you could hear it smacking up against the high and low limits. Went back in, sure enough my solder job of the wire to the end of the sweeper's pivot arm to the pipe of the sender (as pictured above) had failed, I think it was touching one of the other terminals sending crazy info to the poor gauge. Anyway, cleaned it up and resoldered. Since it moves I expect it to eventually fail again, then I'll engineer a better way. But it does work perfectly, for now.
 
It failed again, I pulled it again, soldered it again (through the back of the bracket this time. Vick doesn't have 'em in stock or I'd stop this insanity. It does work perfectly now though. Oh, and the float has had fuel in it this whole time, not much but some, I drilled into it, drained it out and resealed it. I expect that to fail soon too. Hey, it only takes a few minutes to pull it and fix it, so what if I have to do it every tank full, it keeps me out of the bars.
fuelsendergroundwire.jpg
 
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