Fuel sender wits end 66 coronet

[ram250098]

Turns out I bought a new limiter and that was the problem...gauge is very very slow to respond but does show..weird thing is the the temp gauge worked ...insane thing is the limiter was almost $90 Canadian...you guys in the States have it made for part prices...thanks again everyone.
AL

 

[rscurtis]

No one I know with a B Body has a gauge that works properly. I record the miles and fuel at around 150 miles.
New tank and new unit in mine. Won't go past 3/4 no matter what.

I do. Took two senders b4 I found one that ohmed out correctly. It comes off the "full" mark relatively quickly (a hemi will do that), but at least now I know how much fuel I really have.

 

[nm9stheham]

Ummm you don't check the sender with an 'ampmeter'; you measure the sender's resistance (ohms).

Select a low resistance scale; put your meter on one of the scales with the Greek letter Omega; one common low scale is 200 (ohms). You want to be able to read in the range of 10 to 100 ohms. Check that the meter is in ohms by shorting the 2 meter leads together; the reading should change to close to 0.

With the sender out, connect the black lead to the sender flange and the red to the wire connection tab. With the sender float arm moved to different positions, you should measure:
around 10 ohms at full
around 23 ohms at 1/2
around 73 ohms at empty

BTW, the 10 volts that your buddy measured is fairly meaningless; look for the peak reading, it should be near 12 volts. The stock limiter works by pulsing the voltage 12v or 0V to the gauges and sensors; the duty cycle is around 17-18%. It takes special equipment measure this.

If the temp sensor is displaying accurately, the voltage limiter almost HAS to be good...or the limiter has to have partly failed at the same time that the temp gauge or sensor failed in the opposite manner....unlikely though remotely possible. So a good temp gauge is a good sign of a good limiter. If the fuel sender measures resistance as above, and the temp gauge is good, then it is very likely your fuel gauge that is the problem.

And yes, ground the instrument cluster properly!

 

[ram250098]

My mistake I mean ohms...the temp was working which is why I thought the limiter was ok..but when I installed the new one the gauge worked..very strange
Thanks
AL

 

[mopar 3 B]

That has to be why the FSM says not to ground the temp or fuel sender wire for more than 7 sec or the voltage limiter will burn up. Think maybe more of these are tosted due to bad test procedures than actually wearing out.

 

[ram250098]

This is true, it is handy to have long test wires *g*
Today the fuel gauge read 3/4..put gas in and it is above full. Now temp gauge is pegged put a test light on both senders and the light stays on..is this a ground issue?
The voltage limiter does seem a bit sloppy in its slot.
AL

 

[nm9stheham]

You may have multiple issues. You're gonna have to take it one step at a time and test everything as laid out. Otherwise, you'll just chase your tail around and around.

1. Please list the brand/model of limiter you have so we can look it up and figure out how it should work. Some supply a constant 5V and at least one type simulates the original limiter with pulsed 12v.
2. Take your voltmeter, disconnect the temp gauge wire from the temp sensor, and read the voltage out of the wire to ground (battery -). Let us know what you measure there.
3. Do the same for the wire to the fuel sensor and see if the voltage measured is the same as the temp sensor wire. (Should be). Report back with that too.
4. With the wire disconnected, measure the resistance from the fuel sender connector to fuel sender mounting ring in ohms with the meter settings as described. Then move the meter lead from the ring to body ground and again measure resistance. Let us know both numbers.
5. Let us know how fuel is in the tank as accurately as you can.
6. With the engine warmed up to normal operating temp, and with the temp sensor wire disconnected, measure resistance in ohms from the temp sensor connection to the temp sensor body (the outer part with the threads).

If you measure and report all these, a lot can be determined on what is going on. If you would please list your answers numbered like the steps above, it will reduce possible misinterpretation.

 

[ram250098]

Thanks very much for the layout of tests..just started to pour rain here so it will have to wait a bit..what I did just before the rain was I read with the new STANDARD volt limiter installed was a constant 10 volts at both senders, test light did not pulse either just stayed lit

I put the old limiter back in and the temp gauge works with a voltage reading around 0 to 5 volts and as high as 7, at the FULL tank it did show the same
volts..

 

[Icecobra]

I replaced my sender unit recently. For the life of me I could not get the dam thing to go over 1/2 tank if it did it was not by much. Finally i removed the tank and started to check everything. I measured in the tank where the sender should sit on the bottom of the tank and drew a picture of everything and filled in my measurements. It came to pass the sender was designed to indicate a full tank when the tank was filled to the top. Unfortunately our tanks are never full to the top since as your filling fuel will start to run up the filler neck and stops the tank from going full to the top. So as best I can determine "FULL" is about 2 to 3 inches below the top of the tank. I believe this was for natural expansion area for the fuel and air to let the vents and tank work properly. I also believe the guy in china was told make a fuel sender for this tank. He did and did not allow for the area that was to be air and when the sending unit should actually show full. I spent a entire weekend measuring and re-measuring to come up with the where the full mark was and using measured amounts of fuel to test the indicated amounts. I determined that I need to re-bend the float arm so it would achieve empty and full on the fuel gauge at the proper time. It was a pain in the *** and my experience may or may not help others but the tank is not suppose to fill to the top... Close but not all the way.. This in my experience is why some people are having issues with new senders not indicating a full tank. The senders are not properly designed to indicate full at the point the tank is considered full.. Bending the float arm has worked perfect for me... Now when it says "E" I better be at a gas station because it really means it... and "F" means do not try to add more fuel it will go on the ground...

 

[dieseldazzle]

Do you have a replacement gas tank?

 

[ram250098]

No no spare tank...I have had to bend the floats on some other tank to read right, but all in all most have been spot on.
Thanks
AL

 

[dieseldazzle]

My aftermarket tank had a baffle in the middle that was a factory screw up and after going through 3 sending units I took a hard look inside

 

[ram250098]

Just for shits and giggles I did a temp hook up of the old sender that was in the tank and the gauge moves to half..so.. put back in the old limiter and the old sender and she works..sort of..back to square one...where I thought it was the sender..stil could be I guess, maybe got a bad one LOL
I will have to go through nm9stheham check list when I have some more time.
Thanks

 

[nm9stheham]

Thanks very much for the layout of tests..just started to pour rain here so it will have to wait a bit..what I did just before the rain was I read with the new STANDARD volt limiter installed was a constant 10 volts at both senders, test light did not pulse either just stayed lit

I put the old limiter back in and the temp gauge works with a voltage reading around 0 to 5 volts and as high as 7, at the FULL tank it did show the same
volts..

Well it certainly sounds like the new limiter is faulty; it should either show a constant 5v or the pulsing; constant 10V is bad or is the wrong part. I have to wonder if that has damaged the sensors or gauges. Tesign wil lhave to be done to figure that out.

BTW, while you are at ti, check you voltmeter for accuracy; some cheapo auto parts store meter can be 10-15% off. Get a fresh 9v transistor radio battery (the rectangular kind) and its voltage should measure pretty close to 9.6 volts. That is a decent field check of a voltmeter.

 

[ram250098]

Thanks still waiting to see if any of my buds have a spare limiter..going to start from scratch again..yes I am hoping the gauges are still ok after running that 10volt limiter for awhile..
Thanks again
Al

 

[Gpuller]

I would get a voltage limiter from RTE. They are solid state and will protect your gauges from over voltage and short circuits. They also have a flashing LED that will let you know its putting out the correct voltage.

http://rt-eng.com/rte/index.php/RTE_limiter

 

[ram250098]

I looked at the wesite..$50 buck is a fair price..but the $30 for shipping to Canada is out to lunch.
AL

 

[Gpuller]

I hear you but the $30 extra bucks will save a whole bunch if/when the points regulator takes a dump and your gauges with it.

 

[ram250098]

A bunch of buddies are going to Carslile this year so I will see if they can pick up one for me..
Thanks
AL

 

[ram250098]

I had the cluster out and and cleaned everything up. I now have power to all my gauges..temp and fuel..it was the fuel sender, pluged another one in and it reads now.
New problem...I took all the extra crap out that was wired into the exsisting harness and when I started the car the amp gauge pegged when I reved her up...the voltage out of the alt is 15.8 at around 2000 rpm but at the battery it is 14.5 volts..what should the max voltage the alt can be putting out at the stud?
Also the car stalled a couple times as well while idleing.
Thanks
AL