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Fuel gauge and sender


lelshaddai

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I have been searching for an answer. I have a problem with my fuel gauge (53 Plymouth, Suburban) I replaced the sending unit with one out of a 54. It needed to be longer. I fixed that. The sender seems to work as the test bulb gets brighter and dimmer when moved. I have checked the ground to make sure it is secure. However the gauge jumps all over the place. The tank is 1/4 right now and it reads full, then jumps to E, then back to F. It does not register. Is this a faulty gauge?

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Since the gauge is also sometimes jumping to full, you may well have a frayed and shorting wire between the gauge and the tank. Definitely verify the grounds on both the tank and the gauge and look carefully at the wire between the two.

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the wiper on the sender could well be a bit worn or contminated and not making good electrical contact over the full travel of the arm..pulling the sender and checking this with an ohm meter is about the only way to know for sure...unless you happen to have a very percise variable resistor of the proper value wired to ground to simulate the sender across the entire spectrum..

majority of the older style I have found that the pivoting ground point becomes corroded and cause erratic readings..if fixed ground wiper..then the resistor itself is making erratic contact to the wiper..

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Look in your maintenance manual and calibrate your gauge. I had to do that to mine on my 41 Plymouth and it's now in spec. It works great and is accurate. You will need some test leads and a new sending unit, or you could pull out the one in your tank. I made a test stand out of cardboard and did it in the car with all the windows closed. I am assuming that your gauge is calibratible as it is a newer car.

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The windings may be suspect but it could be just crud causing this too...I'd pull the sender and clean it, lube it and try again with good grounds..might be just a bad sender and if you know the ohms rating for the gauge/sender you can simply buy a new one.

Just a quick thought...get uner the car and follow that lead wire to the gauge and make sure it's not opne grounding somewhere along the way...heck run a temporary wire for now to confirm.

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if it is grounded..it will read pegged past the full mark and will probably ultimately damgae the gauge..the use of 10 ohms and 90 ohm resistors will allow you to substitute these values for the sender and place the needle on either empty (higher than no power applied) and on the full mark and not peg the meter beyond the last marker...now you will need to test your sender with an ohm meter to see the exact values..could be 10 and 78 ohms..I used 10 and 90 as this usually will give you a good idea of the guage accuracy/reaction to changing value and associated wiring..erratic behavior is almost always a dirty/poor wiper contact unless you feed wire is just dangling on and the road bumps make and break connection..

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Is there a way to repair the sending units? I will check the ohms and see if it is working correctly. It was jumping back and forth while at idle. It is now pegging half. I had to extend this sender to fit the suburban tank. While testing it yesterday smoke and burn smell came out of it.

Letting the smoke out is not a good thing... Especially in or near a tank full of gasoline.

http://www.ply33.com/Repair/fuelsender.html

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Here's a copy of a post I made a while back..........man making new

sending units. Was on ebay.....don't think he has a current ad. Might

be able to find his business on the net.

While looking on ebay today, I noticed an ad for a new reproduction stainless steel gas tank sending unit.

Seller says it's for 1940-48

Dodge, Chrysler and Plymouth.....complete with float and gasket.

I sent him a note via ebay and asked if he indeed is making these units -

he replied "yes". His ad says he's located in Isanti, MN. He has a "buy

it now" price of $99, with free shipping. Sounds high, but these haven't

gotten any easier to find lately. I have a sender that was new a few

years ago......but, if I needed one, I would grab this one.

It has two wire connection screws......so I don't think it's for a Dodge,

unless he has another one wire unit available as well.

Here's a picture and link to his ad. I would contact him thru ebay with

any questions.

Seller name is tomsclassic. http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT

I have a new unit made by the Atwater Kent Company........looks like

the original one. I think Atwater may be listed in the resources or

similar info at the front of this forum.

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what test did you do to conclude that the tank sender an only the sender is at fault...?

IF when testing this on the bench and you did not apply the voltage to the proper side of the gauge first SW and then from the GA terminal of the guage to the sender..the strength of the winding will make a difference in your current drain..the guage is always drawn toward empty..this is a pernament winding fixed in positon..the variable winding is field is regulated by the reistor in the tank sending unit as it is taken to ground at the tank...

GROUNDS ae critcal on botht he gauge itself and on the tank sender...do verify your grounds..follow you bok for troubleshooting..if you are not you are taking a chance at damage to the guage when only an intermittant ground from a faulty cluster ground could well be the fix...

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Checking the grounds is the next process. I used an ohm meter to test the sending units. I have 3 units. 2 are old and one I purchased used. The very old unit adjusted ohms as it moved. The original one did not move ohms. When I took the cover off it was rusted and full of junk. I am soaking it now and will clean it up and try it again. The third unit is still in the tank.

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  • 3 months later...
Here's a copy of a post I made a while back..........man making new

sending units. Was on ebay.....don't think he has a current ad. Might

be able to find his business on the net.

While looking on ebay today, I noticed an ad for a new reproduction stainless steel gas tank sending unit.

Seller says it's for 1940-48

Dodge, Chrysler and Plymouth.....complete with float and gasket.

I sent him a note via ebay and asked if he indeed is making these units -

he replied "yes". His ad says he's located in Isanti, MN. He has a "buy

it now" price of $99, with free shipping. Sounds high, but these haven't

gotten any easier to find lately. I have a sender that was new a few

years ago......but, if I needed one, I would grab this one.

It has two wire connection screws......so I don't think it's for a Dodge,

unless he has another one wire unit available as well.

Here's a picture and link to his ad. I would contact him thru ebay with

any questions.

Seller name is tomsclassic. http://cgi.ebay.com/ebaymotors/ws/eB...K%3AMEWAX%3AIT

I have a new unit made by the Atwater Kent Company........looks like

the original one. I think Atwater may be listed in the resources or

similar info at the front of this forum.

Has anyone purchased one of these stainless units and if so are you happy with it? Thanks

:eek::D

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post in the thread said listing was removed and NLA

Tim as of this morning he still has one listed for sale. His record says he has sold 50 of them. Just courious before I shell out $100.00 to see if anyone has had a problem with his product. Just my age I guess.

:rolleyes::D

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  • 2 weeks later...

Tim as of this morning he still has one listed for sale. His record says he has sold 50 of them. Just courious before I shell out $100.00 to see if anyone has had a problem with his product. Just my age I guess.

:rolleyes::D

I guess I'll answer my own question. I just recieved my new sender in the mail today. It appears to be of very good quality and certainly better than paying the $200.00 e-bay price for an old original. I'll test it before installation and try and keep everyone up to date on the results.

:D

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I guess I'll answer my own question. I just recieved my new sender in the mail today. It appears to be of very good quality and certainly better than paying the $200.00 e-bay price for an old original. I'll test it before installation and try and keep everyone up to date on the results.

:D

Last week I bought one of these stainless sender units off ebay for my Chrysler, that has one wire, $60.  

 

It looks really good, but it has a couple of problems.  It goes from zero ohms to about 40.  Supposed to be 10 to 90.  And when I put it in a full tank, it read around 5/8.  As I drove it the next few days, the guage went up.  I bent the arm the other way and now the guage moves the right way as I burn the gas out of the tank, but I'm guessing it'll run out when the guage says 5/8.  I took the cap off the inside of the sender and instead of the cone of windings it's a flat winding plate.  Less wiring makes less resistance.

 

Now I need to find a way that will multiply the ohm reading by 2.25.  There's got to be some way to do that.  Any electrical engineers out there?  Could I just put a resistor in line? or parallel? 

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