I dropped my fuel tank to clean it and seal it before I do the full fuel system for e85. When I cleaned the tank I noticed the stock plastic baffle was cracked all around the bottom of the baffle, it wasnt going to last long like that and probably wasnt holding much fuel anyways. So I removed it. Now I am trying to figure out the cheapest and easiest solution for what I have planned with the car.

i know the hydro Mat seems to be accepted with premix, and I've read they work in e85 but not sure if they are rated for it, then the radium options that dont follow my budget for what I want to do right now. If there a simpler solution without adding other tanks or getting into custom fab work? I think a hydro mat might be the cheapest and easiest and just check it every other year?

 

I think I am going to attempt to make 2 "C" shape baffles that are similar height to the stock plastic baffle but I can have tac welded into the bottom of the tank. It wont have a floor to is so I can get it inside the tank easier but this seems to be the cheapest/easiest fix for my problem then 600-1000 for a new tank or a sump setup

 

You can make a replacement "reservoir" out of welded up steel sheet metal that fits over the fuel pump, prefilter and fuel return line - and that attaches to the fuel pump bracket at the stock pump screw. The fuel level float and low fuel sender will bolt onto the pump bracket over the "reservoir" and stay ouside of it.

Much easier and safer than trying to work inside the gas tank itself.

 

If you don't want to fab one, FEED makes one. Not sure if you need the stock plastic tray to install though

https://www.rhdjapan.com/feed-intank...tank-fd3s.html

 

Whatever you make needs a bottom or it's not going to keep fuel where it needs to be. Can you find a good used tank? Fuel starve on an FD could be catastrophic for the engine.

Looked into the FEED at one point. I think all or most of those internal collectors rely on the plastic tray for mounting and guiding the fuel: https://www.rx7club.com/3rd-generati...needed-876090/

Ultimately I just have a plate (you could attach the plate to the hanger or the plastic tub) that goes over the stock tub to prevent fuel sloshing out like they do on the '96 and on tanks.

What is really annoying is our 1988 E28 lemons car which started life as an efficiency model has a better sump baffle straight from the factory. Ran that tank down to empty and driving 10/10ths it still won't hiccup. Last race we were rear ended, lost over 2 gallons of fuel capacity, and it still performed flawlessly down to empty.

All the E28 has is a little cup welded to the bottom of the tank that the pump and filter sock sit in. I think there are a few small holes at the base of it.

The pump return goes right into the cup. The return also goes directly into the sump pickup sock on a stock setup, but our return just dumps into the cup due to aftermarket pump and sock. One other factor is the E28 also has an external filter and high pressure pump under the car. The external pump and filter duo may act as a reservoir of sorts, but I still think the lift pump is pretty simple and bulletproof. See attached photos.

I honestly don't know how it works so well, but I think it's just a function of the cup having a small diameter keeping the fuel closer to the sump. The E28 cup is also relatively tall.

You look at the FD surge bucket... it's long, wide, and the walls are relatively low:



E28 sump assembly:


E28 sump cup - hard to tell height from this photo (not mine):

 

my understanding is the fuel level sensor is the limiting factor on these tanks. I could find a stock tank, but by that time I am probably better off picking up a radium fuel kit or something that is a proven fix for our tanks

I am coming around on the idea of "You can make a replacement "reservoir" out of welded up steel sheet metal that fits over the fuel pump, prefilter and fuel return line - and that attaches to the fuel pump bracket at the stock pump screw. The fuel level float and low fuel sender will bolt onto the pump bracket over the "reservoir" and stay ouside of it."

That seems pretty simple to fab up and install on the fuel hanger and then insert all together. Just make sure the return points into the contain I make, similar to the above picture

im shocked I am the first person to run into this issue, once I saw the cracked plastic baffle I knew it wasnt going to be an easy fix, but I didnt trust any type of glue with e85 in the tank and knew it had to come out.

 

I doubt you're the first person to crack the plastic tub. People have been breaking the metal baffles on track for years so they probably just get a new tank.

As far as attaching a resevoir to the pump/hanger assembly... I think it's easier said than done to get something thru the fuel tank opening.

I had a hard enough time getting my tub cap thru the hole and that was just a sheet of plastic... I can only imagine how hard it would be to get a cube rigidly attached to the pump assembly thru the hole... along with the sender float and everything.

I think you'd probably be better off biting the bullet and buying something we know works or getting a stock tank. FWIW there are alts to the radium like the Coachman IST How to Order. The coahman doesn't appear to require the stock plastic tub.

I am pretty sure the radium tank still utilizes the stock plastic tub to hold the lift pump. That is the radium tank shown above attachign to the plastic tub.

 

To get a reservoir attached to the pump into the has tank opening, ot has to shaped like a babies rubber boot (the kickout for the prefilter.)

If you use hydramat, the reservoir becomes much easier since the hydramat can be below/outside the reservoir as long as it is being dripped onto.
Just take a tall tin can and cut the top off while drilling holes so the hydramat prefilter can attach onto the pump with the reservoir in between and holes directly above the hydramat for the fuel to feed it.

Hydramat doesnt suck air so any fuel contact and its good.

 

Well I made my own

It took a few hours to get it fit into the tank with the other baffles but it turned out quite good. I used JB weld to seal it to the tank, at first I used the JB weld steel stick but it cured so quickly one of the baffles was loose so I had to mix up some of the more standard stuff and add it to adhere it all down, its quite solid.

next will be red-kote the tank to seal it since it was rusting and then drop in the new pump and hanger and were off to the races.

 

The Feed in tank collector works without the plastic.
In most photos it appears to not be sealed as in a bottom but it is, also the door on the side is on a hinge which opens inwards so doesn’t let the fuel out.
It is the best solution if running single fuel pump.