CIS Gas Tanks.......Are they all the same?

[Sunroof]

My question is simply this...............

Are all CIS gas tanks identical on the inside? And can I use a newer CIS tank (1974 on) without making any changes to my 1973.5T?

From what I understand, the only feature that makes the 1973.5T tank unique is that the fuel capacity design of this tank is less and could therefore accommodate a full sized spare tire. From the next model on, the tire saver spare was used which also increased the tank capacity by a gallon or so.

So, is the 1974 - 1983 CIS fuel tank the same inside as the 1973.5T? Do they have the same plastic baffle system, bakelite swirlpot, large screw in meshed filter? I know that the fuel lines (out and return) are configured on the 1973.5T differently when compared to newer tanks, but overall, I believe the fuel pickup in the inside are pretty much the same from 1973.5 to 1983.

I had my tank years ago boiled and the interior coated with "redkote". The coating I learned later can not adhere to bakelite and has made its way off all things non-metal. I am fed up with it and am thinking that just replacing this tank with a new "replica" is the way to finally go. I am seeking some advise here on a replacement and the heck with originality!!!!!! I know Dansk has come out with a replica (CIS tank).

Thanks
Bob
1973.5T

[Sunroof]

Sorry...I stand corrected. The Dansk reproduction is not a CIS tank..............

Here are some photos that have been around for awhile of what the inside of a CIS tank looks like, or at least a 1973.5T tank. Big baffle, bakelite swirlpot with internal mesh filter screw in fitting, fuel pick up lines and the top of the pot. And they rust!!!!!!

[jac1976]

I am far from an expert on this, but I believe the fuel sending unit is different. I have a later tank in my 73.5 and shelved the original tank. Although not installed, I have a 15" Fuchs and a space saver. Since you are planning to replace why not go with an original later Porsche tank and reap the reward of larger volume, a Porsche part, and lower cost?

[Sunroof]

Thanks, but I am not sure what you refer to specifically as to the "fuel sending unit"? I do know that this 1973.5T tank has two external fuel fittings for hose attachment (one out to pump and one back to tank). I am not sure what the 74 through 83 fittings look like. It might be tough to retrofit! Porsche wants about $800 for a new tank, but its not the 73.5T. As I stated earlier, I do not care anymore about originality. I am just fed up with the issues I have now with this tank. The use of the Fuchs wheel and tire saver sounds like a great plan.

The 1973.5T is the only CVIS model with the fuel pump located back near the rear drivers side wheel well. It has to travel a ways to get to the pump, hence hard, hot starts!

[82 SC]

fuel sending unit is where the gas gauge plugs into.

[Avanti]

I just replaced the fuel tank on my 77 with the repro Dansk tank from Pelican. Under $350.00. I did not want to line line or coat my old tank and think its a good alternative and value overall.

Although not internally identical to the original Porsche tank, the Dansk does have a metal whirl pot (sort of) but without a lid. Also, there is no internal baffle or a fuel strainer above the drain plug. When you compare the two, the Dansk tank whirl pot lacks the curved "whirl" section on the inside of the pot.

The two fuel line connections sound like the ones you are looking for, one for the fuel supply on the driver's side of the tank, and a threaded fitting for the return line on the passenger side. They are not located on the far ends of the tank but rather more toward the middle on either side of the fuel pump. Sorry don't have a photo. But I do have a photo below of the whirl pot inside of my Dansk tank before I installed it. Thought it may be needed some day. Like today

It has been mentioned that this is not a CIS tank and it is obviously not the same as the original. However, I assume/hope that some technical thought and testing was applied when Dansk designed their version and decided their lack of a baffle or whirl pot lid was suitable.

I expect for normal driving and occasional spirited driving it is capable of supplying steady fuel. Feedback from anyone with one of these tanks that tracks their car hard would be helpful.

[jac1976]

From Grady Clay...

1973.5 C.I.S. Fuel tank

[Sunroof]

I noted that Dansk advertised the tank as "non cis" so given a choice I would prefer a CIS tank because of the baffle and filter. Their are many aftermarket early non CIS tanks on the market. My frustration is with that interior coating and the filter.