66 Fuel Gauge Issue

[kingchief]

COOL! Thanks Bob. I have a very good C4 core that I was going to sell! Now, I can get it restored. Yeah!

Steve

[kingchief]

OOOPS! My bad! The one I have is a very good C6Z unit. The tube has some rust buildup in it but overall a restorable unit. Thanks again Bob for the contact.

Cheers,

Steve

[s2ms]

Try this guy.     https://desertclassicparts.com/fuel-sending-unit-rebuilding-service/

Awesome, thanks Bob!

Hi Dave,

I will store your fuel in my gas tank?  I will come down and help you.  LOL

Cory

Sure thing Cory. I"ll be sure to fill-up with the 110 leaded at the Co-op first. 

[s2ms]

This turned out to be an easier fix than expected, problem was the little constant voltage regulator that bolts on the instrument gauge cluster backside.

About 1.5 years ago I installed one of the new solid state regulators that apparently was not so.....solid. Never really considered this might be the issue because all the other gauges worked fine, but since the cluster was out to check connections decided to swap in an NOS regulator just in case and bingo, fuel gauge now works perfectly!

[trotrof1]

Thank you for the post repair report and give yourself a pat on the back.

[Lincoln tech]

Yes I remember those they send out a pulsing 6 volt signal.

[greekz]

Thanks for the information.  That is one of the things that make this forum great.

[6s1640]

This turned out to be an easier fix than expected, problem was the little constant voltage regulator that bolts on the instrument gauge cluster backside.

About 1.5 years ago I installed one of the new solid state regulators that apparently was not so.....solid. Never really considered this might be the issue because all the other gauges worked fine, but since the cluster was out to check connections decided to swap in an NOS regulator just in case and bingo, fuel gauge now works perfectly!

Hi Dave,  That would have been my first recommendation, but having the other gauges working was keeping from making the recommendation.  My experience, when the voltage regulator goes out, all the gauges seemed to swing.  Any idea why the other gauges continued to work?

I guess you don't need me to store your 110 octane racing fuel in my gas tank.  Dang.

Good job

Cory

[s2ms]

Hi Cory,

I have no idea why only the fuel gauge was effected, maybe something specific to how it works? I thought all the gauges worked pretty much the same? Anyway, this one had me scratching my head.

I'm still planning to replace the gas tank so you might still have a chance to store some 110...

Dave

[kingchief]

My alternator gauge jumps around! Could that be the constant voltage regulator [new solid state design] also??? Next, where can you find a NOS or used one to try???

Thanks,

Steve

[Royce Peterson]

This turned out to be an easier fix than expected, problem was the little constant voltage regulator that bolts on the instrument gauge cluster backside.

About 1.5 years ago I installed one of the new solid state regulators that apparently was not so.....solid. Never really considered this might be the issue because all the other gauges worked fine, but since the cluster was out to check connections decided to swap in an NOS regulator just in case and bingo, fuel gauge now works perfectly!

The originals are normally extremely dependable. I have yet to see a bad one despite dozens of 65 - 68 Mustangs and Cougars that I have owned or worked on.

[s2ms]

My alternator gauge jumps around! Could that be the constant voltage regulator [new solid state design] also??? Next, where can you find a NOS or used one to try???

Thanks,

Steve

Steve,

Still pretty plentiful, do a search on ebay for B9MZ-10804-C, you will see several ranging in price from about $35 to >$100. Mostly Motorcraft but here's a FoMoCo: https://www.ebay.com/itm/314420424288

Dave

[Royce Peterson]

My alternator gauge jumps around! Could that be the constant voltage regulator [new solid state design] also??? Next, where can you find a NOS or used one to try???

Thanks,

Steve

The alternator gage is not in the circuit of the CVR so it is not involved.

[kingchief]

Thank you for the info and I apologize for getting off topic.

Cheers,

Steve

[66S285]

I think your fuel sender float has a hole and is filling with some amount of liquid. Easy fix. Happened to me as you describe.

Agree same for me