Fuel sending unit

[shadango]

not necessarily. even with less voltage, that path of least resistance to ground the gauge will still peg. The replacement sender was checked before it was sent out. IS the boot connector tight? or the wire cracked at the boot.

The boot is tight and the connection is clean....the wire appears to be in good shape...the exposed part in the trunk/underneath the car are soft and flexible yet.

I would think that if the wire had a break or a short to ground it wouldnt work "fine" (as far as level) after tweaking the float arm...the dead spots I had in the last one were not random, they were in the same spot every time indicating a problem with the sender...they were in the same spots every tank. A wiring issue wouldnt cause that.

I hooked the last (and this) sender up to the wiring while out of the gas tank and at the empty stop on it , the gauge read empty...at the full stop it read "full".  Only once it was in the tank did the level not show right, indicating to me that it is a calibration issue with the sender to the level of gas in the tank more than anything else.

Bench testing showed the proper ohms at the top and bottom of the scale, going by what others have posted as far as the proper readings.   The dead spots were small enough where my shaky hand could not pick them up while cycling the arm through the range and watching the ohms.  Only once installed were the two dead spots seen. On the rock auto sender I had tried, the deads spots were much bigger and easier to find.

Can I ask how the sender was tested? And was it tested for dead spots, level or both?   

[mopardave]

i would have to call the manufacture.

[shadango]

i would have to call the manufacture.

I'd be curious.

Because, like I said, I think the calibraton of the unit is "wrong" for the tank I have at least, given my testing.

I did a search on google and found many other people talling about how the repop units just dont work right.

What I cant figure is how one person here has a great experience with them and then I and others do not....that makes me wonder if there isnt some issue with differences in the tanks? That seems like the only logical variable....the sender worked fine hooked up to the car but out of the tank as far where full and empty are set....but that setting doesnt seem to jive with the actual fuel level in the tank.   

T

[tommyg29]

like I said before, the sender I bought from roseville never read above 5/8 tank, until I replaced the tank and now it seems to work properly. I still think the separator box had something to do with it.

[shadango]

I couldnt see into my tank once it was mounted.....

The tank you had -- did you have the 4 lines running into the tank on the right side?

The diagram in my fsm shows those lines go to each corner of the tank, no internal tank on my 72.....

[tommyg29]

yes, it has the 4 lines going to each upper corner. You can one of them in the picture above. My new tank has the 4 lines without the box.

[shadango]

Well, I went to fill up my tank tonight for the alignment tomorrow, and found I had a major gas leak at the sender unit gasket.   

After draining some fuel I was able to pull the unit out some and peer inside...I could see no internal extra tank......

Man, that gasket is a PITA.    And the locking ring is not much better.   Looking at them, it seems like they are both just a bit smaller than they could be, which leads to issues aligning them and getting things cinched down tight.

i wish I hadnt chucked my original locking ring...the new one just BARLEY grabs under all 3 tabs on the tank.   

Its holding tight now, just hope it STAYS leak free. 

Cross your fingers for me, guys.  LOL

[drewcrane]

yea i had the same problem the sending unit does not work right, and when i finally got it to stop leaking i just left it as is,and hope fully this spring/summer i will try to open this can o worms again 

[ajantics]

  This thread is making me a little nervous. I need to order a new sending unit that has a return on it when I install my 440 stroker with efi. Since my sending unit seems to be working maybe I can find another way to install a return line on my existing unit?

[drewcrane]

This thread is making me a little nervous. I need to order a new sending unit that has a return on it when I install my 440 stroker with efi. Since my sending unit seems to be working maybe I can find another way to install a return line on my existing unit?

i might install this tank with the pump inside

http://www.xvmotorsports.com/products/category/index.cfm?cid=17&lvl=1

and this way you can have the inlet/ outlet seperate from the sending unit

[ajantics]

  I was looking at that but man....$879.95?

[shadango]

Well, ran the tank down......

I still have 2 dead spots...this time, both at around half ...one towards the high side of half and one right as it dips between half and quarter.....

The dead spots appear to be even "smaller" than the last time.....they dont stay dead as long.
I got to 1/4 tank and refilled and it took just the right amount.

So, the sender is reading correctly for now.  Until there seems to be a better alternative I am leaving it as-is.

I am not really happy to have had to go thru what I did to make the gauge read correctly....but what is more frustrating is have dead spots at all.

But I guess it is what it is and I will live with it as-is for now.  I have to move on to other stuff that needs done......LOL

I know I will be keeping my eyes open for a solution though.

[drewcrane]

I was looking at that but man....$879.95?

oh i know brain damage price,they are trying to take advantage of us poor mopar dudes,knowing the problem they have a pretty good fix but want to over charge due to the value of our cars

[solarguy]

I agree with what DocMel posted.  Try running a jumper wire from the guage to the sending unit, bypassing the factory wire.  Simply grounding the sending unit wire and having the guage peg proves the guage works when fully grounded with little resistance.  The sending unit has a resistance value to ground dependant upon the fuel level and that signal back to the guage can be distorted using the old wire.  Also, make sure the guage frame in the dash is grounded good, maybe a temp jumper there too would help.
My old '70 vert needed a new wire from guage to sender even though grounding the original sending unit made guage peg. 

I'm dying to know the outcome of the fix, stick with it. 

[shadango]

I agree with what DocMel posted.  Try running a jumper wire from the guage to the sending unit, bypassing the factory wire.  Simply grounding the sending unit wire and having the guage peg proves the guage works when fully grounded with little resistance.  The sending unit has a resistance value to ground dependant upon the fuel level and that signal back to the guage can be distorted using the old wire.  Also, make sure the guage frame in the dash is grounded good, maybe a temp jumper there too would help.
My old '70 vert needed a new wire from guage to sender even though grounding the original sending unit made guage peg. 

I'm dying to know the outcome of the fix, stick with it.

I am still confused as to this fix.....

Right now, the gauge works 100% correctly as far as level....showing the proper level in the tank....except for a couple of dead spots, which happen in the same spots every time....right around half and then around 1/4....strangely enough, same as the last sender I tried.   That would seem to indicate an issue with the car somehow, but what?

If the wiring was the problem there would be two scenarios possible....a momentarily broken or shorted wire= dead spots randomly happening, or a wire that is shorted or broken "permanently" and then you would have a consistent low or no reading, but no dead spots in any repeatable locations......

But mixing the two seems to indicate to me another issue.....