Fuel Gauge

[headscratcherona65]

I am in desperate need of help on figuring out a problem with my fuel gauge not working....first of all I have 3 wire diagrams...I am pretty well knowledged but I am stumped....I challenge anyone to solve this untypical problem........when my fuel gauge is installed in the tank it does not work......outside the tank it works.....no it is NOT a ground issue....please help!!!!

 

[horse sence]

There is only a few reasons that it would work outside the tank and not on the tank.
Either there is a grounding problem
The float has a hole and is filling with fuel
The float rod is hanging up inside the tank .

What does it read when it is in the tank ?

 

[headscratcherona65]

There is only a few reasons that it would work outside the tank and not on the tank.
Either there is a grounding problem
The float has a hole and is filling with fuel
The float rod is hanging up inside the tank .

What does it read when it is in the tank ?

I have about 8 gallons in it and it reads 1/4 tank.....it is a brass float...no fuel in it.......I have shook the tank several times to make sure it wasn't sticking.....I have a new solid state voltage regulator on my instrument cluster....I know it seems simple but I don't get it

 

[horse sence]

That is why you need to check it on empty .I think it should have around 4-5 gallons and the 1/4 mark .I would drain the tank ,add one gallon and set the float at empty .you will have to bend the rod .

Does it read full with a full tank?

 

[headscratcherona65]

That is why you need to check it on empty .I think it should have around 4-5 gallons and the 1/4 mark .I would drain the tank ,add one gallon and set the float at empty .you will have to bend the rod .

Does it read full with a full tank?

Ok...Im game for anything.....I will drain the tank again for the 5th time but I really don't understand how I can tell if its working on an empty tank?.....so drain the tank....add a gallon before I install the sending unit I guess is what you are saying and set the float to empty?....Im with ya but I have been doing an ohms reading and physically watching the gauge move correctly when operated by hand....empty reads empty and full reads full when moved to each stopping point...as far as what it reads full....I havnt filled it up completely full but I did put 8 gallons in it and I know that should be about a half tank at least....I can tell you know what you are talking about and I REALLY appreciate the help.......I will go ahead and fill the tank completely to give you that proper answer....then drain it and go from there.......after we figure out this problem I have another one that is baffleing as well but one thing at a time.....I am 56 years old and have had 2 65 coupes and a 73 Mach 1.....that was my dream car...I love this little coupe...I have completely redone the interior and after we figure out these couple problems I can get working on my exterior paint......I know what Im doing...but over looking something....that's what gets challenging lets say....if you thnk of anything else before I get back to ya tonight...Please feel free to say....Thanks Jim

 

[headscratcherona65]

Ok...Im game for anything.....I will drain the tank again for the 5th time but I really don't understand how I can tell if its working on an empty tank?.....so drain the tank....add a gallon before I install the sending unit I guess is what you are saying and set the float to empty?....Im with ya but I have been doing an ohms reading and physically watching the gauge move correctly when operated by hand....empty reads empty and full reads full when moved to each stopping point...as far as what it reads full....I havnt filled it up completely full but I did put 8 gallons in it and I know that should be about a half tank at least....I can tell you know what you are talking about and I REALLY appreciate the help.......I will go ahead and fill the tank completely to give you that proper answer....then drain it and go from there.......after we figure out this problem I have another one that is baffleing as well but one thing at a time.....I am 56 years old and have had 2 65 coupes and a 73 Mach 1.....that was my dream car...I love this little coupe...I have completely redone the interior and after we figure out these couple problems I can get working on my exterior paint......I know what Im doing...but over looking something....that's what gets challenging lets say....if you thnk of anything else before I get back to ya tonight...Please feel free to say....Thanks Jim

ok.....I filled the tank completely full....it reads almost a half a tank...not quite......also I took a volt reading behind the fuel gauge on the terminals....I had a solid 5 volts going in and a solid 5 volts on the other terminal coming out....now,with that said....just after 3 minutes or so I still had 5 volts on one side but only 3.25 coming out on the other terminal.......am or can I be loseing voltage through the gauge?.....how many volts does it take to operate the sending unit

 

[headscratcherona65]

ok.....I filled the tank completely full....it reads almost a half a tank...not quite......also I took a volt reading behind the fuel gauge on the terminals....I had a solid 5 volts going in and a solid 5 volts on the other terminal coming out....now,with that said....just after 3 minutes or so I still had 5 volts on one side but only 3.25 coming out on the other terminal.......am or can I be loseing voltage through the gauge?.....how many volts does it take to operate the sending unit

gonna play with it some more....driving me nuts!......any more thoughts?