Another sending unit bites the dust.

[oldchevelle541]

I have not found any repo unit that works, including Mancini. Have yours rebuilt or pay for an NOS. And yes, a DMT gasket and thick ring is a must. Mine works somewhat, usually 1/4 tank off but I always conservatively track mileage and don't push it.

I emailed Mancini today to verify the part number for my 69 GTX. They sent me links for early 60's (not 69) sending units. Then they sent a link for an AMD gas tank. Who was asking for a gas tank - not me. This is exactly the reason why I pull back and rethink thngs further.

 

[oldchevelle541]

That’s the same one I have, including the lock ring you posted, no leaks whatsoever.

View attachment 2017081

I am ordering 2 gaskets and one locking ring tomorrow. Thanks.

 

[oldchevelle541]

Had a few minutes today to recheck size of fuel lines. I am attaching 2 pics of which shows the originality of the sending unit. Very crusty and dirty. I used a set of calipers to measure outside diameter of both lines and to my surprise the main output fuel line is 5/16" OD. It measures the same at the carb as well. The adjacent vent line is 1/4" OD. If anyone out there has a true survivor or a manual can you verify my findings. I just assumed it was a 3/8" out let line all along. I am glad I did not order anything yet.

View attachment 2017285

View attachment 2017286

Next Step - will get back under car and clean off sending unit flange to look for a part number. This was an early build car with auto and open rear 3:23 so it is possible they put in a 5/16" line but I have to really confirm. Will post part number should I find one.

 

[dadsbee]

If the sender has a 1/4" return line, then it will have a 3/8 outlet. Now why is always the question, as even my '70 Superbird only has a 5/16 line to the fuel pump! Most did...

 

[Cojohnso1]

My fuel gauge was failing when I first got my '69 GTX. I too lived the "Fill frequent" route. I have a new Dorman sending unit that I wasn't enthusiastically looking forward to using. I drained the tank. And because of scheduling circumstances I left empty for a few days. I was forced to move car, thus put new fuel in. And you can probably guess. The gauge started working. I went under the impression that the float probably had a crack. Thus fully cleared with the empty tank. I was anticipating the float to fill again, thus sink to bottom of tank. And register as on empty, once again.

That was two years ago. And from my math the gauge is still very accurate.

I know "Self healing" is not ideal. But thought I would share my episode.

 

[oldchevelle541]

Next Step - will get back under car and clean off sending unit flange to look for a part number. This was an early build car with auto and open rear 3:23 so it is possible they put in a 5/16" line but I have to really confirm. Will post part number should I find one.

Just got some crude off the unit and saw the pentastar imprint and a few letters (see pics) but no part number. I noticed on the reproductions there is not a 5/16" line available with a 1/4" vent hence this must be a 3/8" unit that was hooked up to a 5/16" body fuel line. Here are pics.

 

[oldchevelle541]

Just got some crude off the unit and saw the pentastar imprint and a few letters (see pics) but no part number. I noticed on the reproductions there is not a 5/16" line available with a 1/4" vent hence this must be a 3/8" unit that was hooked up to a 5/16" body fuel line. Here are pics. View attachment 2017322View attachment 2017323View attachment 2017324View attachment 2017325View attachment 2017326View attachment 2017327

BTW - does the locking ring flange look standard to you - It looks different to me that what online pics look like.

 

[dadsbee]

Lock ring is factory.. not sure what you see wrong with it other than 55 years of dirt!

 

[oldchevelle541]

If the sender has a 1/4" return line, then it will have a 3/8 outlet. Now why is always the question, as even my '70 Superbird only has a 5/16 line to the fuel pump! Most did...

its a head scratcher.........

 

[oldchevelle541]

My fuel gauge was failing when I first got my '69 GTX. I too lived the "Fill frequent" route. I have a new Dorman sending unit that I wasn't enthusiastically looking forward to using. I drained the tank. And because of scheduling circumstances I left empty for a few days. I was forced to move car, thus put new fuel in. And you can probably guess. The gauge started working. I went under the impression that the float probably had a crack. Thus fully cleared with the empty tank. I was anticipating the float to fill again, thus sink to bottom of tank. And register as on empty, once again.

That was two years ago. And from my math the gauge is still very accurate.

I know "Self healing" is not ideal. But thought I would share my episode.

That makes total sense so if you just had a new brass float tube maybe the old one works. The thing I tried however was to elevate my float arm from empty position to where it would be close to full using a long non-conductive road inserted via filler neck. I could feel the float. Turned the key to on and nothing. If needle would have moved I would buy just the float tube and get everything working again.

 

[dadsbee]

its a head scratcher.........

Nope, like I said the majority are that way. 3/8 outlet and 5/16 tube. 5/16 hose as a joiner. Here's the OE part number on a '70, made on the 240th day of 1969

 

[oldchevelle541]

Lock ring is factory.. not sure what you see wrong with it other than 55 years of dirt!
View attachment 2017328

nice and clean......curious if the gasket below the unit is a flat gasket or O-ring. My issue is without a lift I cant even see the thing even with car up in the air a bit.

 

[oldchevelle541]

Nope, like I said the majority are that way. 3/8 outlet and 5/16 tube. 5/16 hose as a joiner. Here's the OE part number on a '70, made on the 240th day of 1969
View attachment 2017336View attachment 2017337View attachment 2017338

Thanks for sharing .....I assume those numbers are located underneath the locking flange.

 

[dadsbee]

 

[oldchevelle541]

View attachment 2017346

thanks dadsbee - I am eventually pulling the unit at some point so I am going to get these today from Detroit Muscle Tech.

 

[oldchevelle541]

thanks dadsbee - I am eventually pulling the unit at some point so I am going to get these today from Detroit Muscle Tech.

order for new locking ring and a few gaskets (you never know) placed yesterday.

 

[Mopar Hunter]

Good idea.

 

[oldchevelle541]

Quick question to all - it is my understanding that the original factory units were not stainless steel yet so many reproduction units are stainless steel. Why? I was always under the impression that stainless was not as good as a ground for the grounding strap as is the non stainless. I can see stainless fuel lines under the car because they are exposed to so much but a sending unit is pretty much inside the tank. If anything I would worry about the other small components that make a sending unit work not so much the metal frame.

 

[Darrah]

Quick question to all - it is my understanding that the original factory units were not stainless steel yet so many reproduction units are stainless steel. Why? I was always under the impression that stainless was not as good as a ground for the grounding strap as is the non stainless. I can see stainless fuel lines under the car because they are exposed to so much but a sending unit is pretty much inside the tank. If anything I would worry about the other small components that make a sending unit work not so much the metal frame.

Stainless is perfectly fine as far as electrical conductivity in this situation. Technically it's not as conductive as something like copper, but it won't add appreciable resistance to impact a fuel level circuit.

As far as why most are made of stainless now, I think it's purely due to corrosion. If you've ever pulled a sending unit from a car that isn't used often, they can get REALLY crusty. Maybe not a big deal for a car driven daily, but I don't imagine most of our cars fall into that category. The inside of a fuel tank is a surprisingly great place for rust to form when not constantly in use.

 

[oldchevelle541]

Stainless is perfectly fine as far as electrical conductivity in this situation. Technically it's not as conductive as something like copper, but it won't add appreciable resistance to impact a fuel level circuit.

As far as why most are made of stainless now, I think it's purely due to corrosion. If you've ever pulled a sending unit from a car that isn't used often, they can get REALLY crusty. Maybe not a big deal for a car driven daily, but I don't imagine most of our cars fall into that category. The inside of a fuel tank is a surprisingly great place for rust to form when not constantly in use.

Thanks for reply.....much appreciated.