Mazdatrix shows different tanks for 79-80, 81-83, and 84-85. I know the 84-85 GSL-SE tank has a cup that the fuel supply and return fit into. What's the difference between the other versions?

 

79-80 is different on top due to the spare tire well, 81-85 non -se is fundamentally the same and will swap no problem. The -se tank has larger lines, and the pitiful slosh cup.

Are you just replacing a bad tank, or do you have some performance goals? The s4 pump hanger and slosh cup go really nicely into an 81-85 tank.




Isaac

 

Somewhere in there is also a capacity change when the spare tire changed from a full size to the donut type. IIRC it went from 14.5 to 16 gal.

 

I'm looking at replacing a tank and want to know which years will fit in the car. Thanks for the info.

 

true, i think 79-80 is the small one, but i could be wrong.

 

Right, 79-80 were like 14.5 gallons, vs ~16.1 in the 81-85 tanks. I believe that the 81-83 and 84/85 tanks are not 100% interchangeable though. I can't remember for sure, but I thought there were some slight differences in the tops of the tanks (and the frame rails on the cars) that make them not bolt right in.
I'll see if I can find that thread...

 

well i know my 84-85's have had drain plugs and my 82 doesn't... also i think the 84-85's have a bolt on fuel pipe setup, and the 81-83 the pipes are welded/brazed on the tank.

 

I think I have it. The S1 (79-80), S2 (81-83) and S3 (84-85) appear in order below. I can't tell by the images which tanks would physically fit in which cars (aside from the car it was designed for), but at least I can pick them out of a lineup

 

I have a tank from an 83 sitting here along with one from a 85. Exactly what he said. Same exact dimensions. Both tanks are fundamentally junk. The 85 is 'almost' save-able but I'm sure there's got to be something from a different car that will fit in a 34 wide 24 front to back and 8.5 deep in there. I know several are close but I'm going to have to start researching again and find something. I'm NOT paying $500 for a gas tank. That's crazy!

 

83 tank will not bolt into an 84-85 car. You might be able to make it work, but the top of the tanks and the placement of the spare tire well are different between these years. I believe 81-83 are the same, but I haven't verified that in person. There is a thread with pictures that I posted of the difference in the car chassis. I'll see if I can find it. The link has more pictures of 83 and 84/85 tanks. You can see the difference in the width of tank tops and the removable pickup plate J9 mentioned.
83 GSL and 84 GSL-SE Fuel Tanks

84 SE left, 83 GSL right

 

Here's a couple threads where this was discussed.
https://www.rx7club.com/1st-generati...y-late-961990/
https://www.rx7club.com/1st-generati...s-tank-628743/

 

^Thanks. I was having a hard time finding that thread (was in a rush) yesterday when I posted.

 

the frame rails are wider on the FB compared to the SA22C by about 2" I discovered this when building my last car. The fuel tanks from the SA22C are smaller and can be swapped to the FB but a FB tank can not fit a SA. This is due to the full sized spare the SA22C came with vs donut of the FB.

 

Anybody know whether using a tank from a gsl-le in a gsl-se is okay?

 

I don't know what a GSL-LE is. In '84 - '85 cars, the tanks are similar, but the GSL-SE version has a cup in the bottom that's supposed to prevent fuel starvation. If you use the non -SE tank, I imagine you'll have more issues with hiccups in fuel supply at low tank levels. Injected cars don't have the natural fuel reservoir of a carburetor float bowl.

 

I can tell you directly. On the street, you notice it starting at about 1/8 tank, starting with lefthand turns. The longer and harder the turn, the earlier you notice it. Hiccup followed by a few seconds of low fuel pressure.

On the rallycross course, I was running into starvation with half tank Good thing N/A rotaries are so tolerant of lean mixtures.

I think I found room under the car for a roughly one liter surge tank and a second pump to fill the surge tank that feeds the main pump, but it's going to look like a thick bramble of plumbing under there when I'm done. A liter *should* be enough to keep my engine fed for about half a minute to 45 seconds even if the fill pump is sucking air the whole time AND I'm running at peak flow. So it should be overkill enough. (And the fill pump flows ~2200cc minute, and the engine return also goes to the reservoir, so we're good there too)

 

About 4 yrs ago I did a gslse fuel tank and hard line swap into my 83 S with the help from slammed gsl

 

Where's that info for swapping the S4 pump hanger and cup to the SE tank?

 

If you're looking to avoid fuel slosh and starvation, a surge tank is the ultimate solution, as peejay mentioned. If you're interested in that route, I developed an in-tank version which eliminates a lot of plumbing and associated issues --> https://www.rx7club.com/build-thread...a-fbs-1035921/

PM me if interested.

 

Does anyone know where I can get a fuel tank for my 1979 rx7, it is in the shop and they said that it is rusted on top too badly to repair?

 

You'll need ti find a used one. Put a Want To Buy in the classified.

 

Does anybody have a closeup picture of the tank flange for the sending unit?

My tank in my 82 FB had been removed and refurbished, it is very nice inside and out....

But I have yet to successfully fix the leak at the sending unit. The flange looks ok, I have gone through 3 OEM gaskets with various levels of tightening the philips screws and can't make a good seal.

Wondering if the flange got modified somehow when the refurbished the tank...

 

what price are you looking for?

 

hi this fuel tank is available