Fuel gauge issues

[Retoohstyoh]

Removed auxiliary tank. Removed, cleaned and installed rear tank. New fuel line and sender. Fuel gauge barely gets to E but does move. Circuit tested the plug at tank and it’s blinking like it’s getting intermittent power. Anyone ever experience this or know what’s going on?

 

[B RON CO]

Hi, the fuel, temp, and oil pressure gauges receive a pulsing voltage of @ 6 volts from the instrument cluster voltage regulator, which is on the back of the gauge cluster, and feeds each gauge.
It sounds like you are detecting this at the fuel sender.
How much gas is in the tank?
Some guys will ground a new sender and work it from empty to full a few times to check it before the install.
The sender in the tank needs to be grounded to work properly. Good luck

 

[Retoohstyoh]

There is about 4 gallon in the tank. I cleaned the ground but will double check. Maybe I should pull and check the new sender before adding more fuel. Maybe I got a bad one. The fact that the gauge is moving at all has me puzzled.

 

[Retoohstyoh]

I pulled the sending unit and adjusted the float. That simple it started working. The tank was 3/8 full and reading below E. Note to self, check the function of aftermarket parts before installing next time.

 

[DirtDonk]

Check them all. My OE factory senders both read low from the factory. Would not go above 3/4 tank when full.
Brand new from Ford (in about '78 or '79 maybe?) read about the same.

Only way to get them to read correctly was to bend and tweak the float arm and the stops. Reads about a needle's width over full when topped off, and about the same below empty when it literally runs out of gas.
On EMPTY there are just a couple of gallons left.
Ended up using the originals and using the factory replacements in another vehicle.

Paul

 

[Tonyduc]

Hi, the fuel, temp, and oil pressure gauges receive a pulsing voltage of @ 6 volts from the instrument cluster voltage regulator, which is on the back of the gauge cluster, and feeds each gauge.
It sounds like you are detecting this at the fuel sender.
How much gas is in the tank?
Some guys will ground a new sender and work it from empty to full a few times to check it before the install.
The sender in the tank needs to be grounded to work properly. Good luck

All of my gauges fuel, temp, oil, show a low reading, the needles go up 1/8" then stay there. Could the cluster regulator you refer to be the issue ?
Thanks
Tony

 

[B RON CO]

Hi the original instrument cluster voltage regulator is a bimetal strip. The newer ones are electronic.
As far as I know, they either work or they don't.
If you have a multi meter I would check the voltage at one of the sender wire plugs. If the pulsing voltage is very low, below @ 3 volts I guess it could be the ICVR.
It could also be loose or corroded connections or bad grounds. I would check the voltage and connections first, before changing the ICVR.
Good luck

 

[DirtDonk]

All of my gauges fuel, temp, oil, show a low reading, the needles go up 1/8" then stay there. Could the cluster regulator you refer to be the issue ?

This is why all the information you can provide is more helpful than not.
Yes, it can definitely be, and most likely is, something related to the regulator or it's power circuit.
When all three gauges act up equally, it's almost always on the common shared power side of all three and not the three individual sensors.
Sure, over time all sensors can fail and cause similar issues, but it's rarer than the IVR failing.
Or needing adjustment.
Or needing it's power source checked.

Make sure that full battery voltage is reaching it first. If so, measure the output.
Also check the condition of the power connections as they may have become corroded over the years. Ford did a good job of making it's wire terminations and splices, but age will convert just about anything given the right circumstances.

Most IVR's are adjustable to a certain extent. Yours is reading pretty low, so hard to say if it will be adjustable enough to compensate. You may end up needing a new one.
But even the new electronic ones need adjustment now and then. We got a "bad" batch a few years ago that read about 3v output, instead of the 5 to 6 volts it should have been. I was able to tweak the little adjuster screw until each one read properly and they were good.

I even had to adjust my original factory regulator one time in about '79 or so. Noticed that all the gauges were reading just a tiny bit low, compared to when I'd bought it just a few years before. Worked fine without further adjustments for the next 30 years or so.

Paul