M3Run

Hello Hello!
I have a 87 FC Rx-7 that did not start when i got the car. After slapping a newly charged battery on it, i got it to crank. Then after poking around with it, i got it to start only on starter fluid. Then i took apart the fuel pump assembly of the car. The fuel pump was super rotted out. I need to get a new assembly for it. I drained the gas from the gas tank and it was super brown. Also the gas tank itself is very rusty inside with a bunch of rust sediment at the bottom. My questions are, would i be able to just put gas and a new fuel pump assembly and run it? Or should i replace the gas tank? How hard is it to take out a gas tank on a 87 FC? Should i just replace the gas tank with another used but clean one? Try a Fuel cell? Is it hard to install and plumb fuel cells? I heard braided lines are needed for a fuel cell? Sorry for the lots of questions but im just trying to figure out options. Anything will help. Thank you!

Aaron Cake

iTrader: (1)

The tank must be cleaned or replaced otherwise you will continually contaminate the fuel system. It sounds like this car has been sitting for a while. In that case, check out:

Removing An RX-7 From Storage, Dealing With Improper Storage

Now back to the fuel tank. It isn't very hard to remove the tank. Instructions are found in the FSM and Haynes.

The Factory Service Manuals for all years of RX-7 (and many other rotary cars) can be downloaded for free here: Foxed.ca - Mazda RX-7 Manuals . They contain all common service information and more, and are an essential tool for any sort of service work that needs to be performed on these cars.

Additionally, the Haynes service manual for the 1986 thru 1991 RX-7 (both turbo and NA) can be found at most local auto parts stores or purchased from any good bookstore (ISBN number 1 56392 007 7). It is only about $25 and is a great quick reference for things like this. Not only does it contain most of the information in the FSM condensed into an easy to read format, but it includes full wiring diagrams as well.

These manuals will answer 99% of service related questions for the car and if you intend to do your own repair work, you will need at least one of them. Preferably both, since the FSM is a free download. The Haynes is a good quick reference covering 99% of questions, while the FSMs show complete and detailed procedures.

Basically remove the catback exhaust, disconnect the fuel lines and electrical via the access panel in the hatch, disconnect the fill and vent tube, remove the straps and lower the tank down.

New tanks probably are still available. But if yours is decent, just rusty, then you can clean it out and seal it yourself if you want to put in the effort.

Here's how I did mine:

M3Run

I will definitely look into it. I just need to see on how to get the gas tank out. Anybody have any experience with fuel cells?

Aaron Cake

iTrader: (1)

Lots have experience with fuel cells.

There are no drop in fuel cell replacements. It's really only something to consider if you are building a track car.

M3Run

Ohh cool thanks man. I was really thinking about it though. Due to the fact that the tank i have is super rusty and removing and replacing it would be a pain lol. So far ive been trying to take the old tank out for cleaning but it sucks without a lift lol and the bolts are kinda rusty. Any tips on removing FC fuel tanks?

Aaron Cake

iTrader: (1)

Removing the tank is basically the procedure in the FSM/Haynes. But of course those books don't tell you much about rust.

Really the only thing you can do about the rust is to soak everything constantly with PB-Blaster, use a wire wheel to clean as much rust as you can, put a breaker bar on the ratchet and hope for the best. Obviously we can't use a torch around the fuel tank.

Once you have the tank out you will likely find the screws holding the pump flange on totally rusted. An impact driver is the best tool for this but expect to drill some heads off. Then at least you can unscrew the shafts with Vice Grips.

Once you see inside the tank you can determine whether it is worth restoring.

Backinthe game

I ended up buying a used tank that had no rust issues for only $100 on CL might save you the hassle of trying to clean and seal it.

M3Run

After ive looked into the tank and its just heaps and heaps of rust. Good thing is that its mostly like sediment rust and accumulated at the bottom. I can easily scrape it off. Its not like the actual tank itself is rusted i think just the old gas turned to rust but did not stick. But theres lots of it. Ive managed to loosen the front bolts of the tank straps. No access to the back though. Everyone said to just bend the straps so that will be done next. Also taken out the heat sheilds. I contacted a radiator shop so once its out they will take it and sand blast it, inside and out. Then reseal the inside and paint the outside. For about $150. Just waiting on good weather to take the tank out.

Aaron Cake

iTrader: (1)

Just be warned, that a friend had his tank sand blasted then sealed at a reputable local shop.

It then took 5 fuel filters to remove all the sand from the fuel system, one ruined set of injectors. Got to the point where he installed a tractor filter at the sump of the tank so that it could be cleaned out constantly.

And then the coating started peeling.

lduley

iTrader: (1)

Ya, sandblasting a tank isn't a great idea IMO, if you wanna be cheap (what 7 owner isn't?) you could get some gravel and a gallon of mineral spirits or kerosene, put it in there and slosh it around, dump and repeat a couple time and it should be pretty clean, just make sure you get ALL the gravel out, and let it dry, like a week

M3Run

Damn. Idk now lol thinking of options. I got the tank out. But now deciding on getting a used one for 250 or getting it cleaned for 150. Also i broke something off my tank lol. The middle part. Which is like a vacuum line or something. The little plastic nipple broke. Idk what it is and if its easy to find replacements. The little part in the middle.

Aaron Cake

iTrader: (1)

It's a check valve for the evap system.

Dealer should have a replacement, not very expensive. There is also a gasket needed.

erick31876

iTrader: (8)

You can get rid of the rust using electrolysis,I did that on my tank,and it came out like new.it was very bad when I removed it. It's very simple,there is a ton of videos on YouTube about it. Basically all you need is a battery charger,a piece of sacrificial metal for the rust to go to,it used a threaded rod. A block of wood with a hole drilled in it for the rod to go through and hold it. Sodium carbonate which is pool ph booster,and arm and hammer washing soda.to do it ,yourself fill the tank with water,put in some sodium carbonate,hook the positive lead up to a bare metal parts of the tank ,put the threaded rod through the block of wood,I used a nut to hold it from falling through,insert the metal rod into the water,making sure it dont touch any part of the tank,i put it in where the fuel pump mount is ,using the block of wood to center it and to keep it from falling in and from touching the metal,then you hook the negative lead up to the metal rod,turn the charger on,leaving it sit over night.after a couple of hours you will see all kinds of crap sticking to the metal rod,and the water will start to look like a rusty soup. The longer you leave it sit, the more rust it will remove,the time it will take varies on how bad it is
Mine took just sitting overnight and it came out perfect

Phx79RX

I reccomend the electrolosis as well used the above method on a mc tank with amazing results!
be sure not to reverse polarities though or it will rust away completely!

Electronaut21

i may try the electrolysis method on a few tanks i have at home...

could you theoretically do this to the outside too, provided you have a large enough vessel for water? like submerge the tank?

Phx79RX

Definately easier to submerge and keep the tank within the solution ! I just scored an industrial size unit that i hope to adapt to do this process soon it came off of a cooling tower supposedly they spent around 15k on this unit to treat the water seemed to work pretty well its going to have to wait though im getting the 7 back together just got a t2 transplant!!

Phx79RX

Definately easier to submerge and keep the tank within the solution ! I just scored an industrial size unit that i hope to adapt to do this process soon it came off of a cooling tower supposedly they spent around 15k on this unit to treat the water seemed to work pretty well its going to have to wait though im getting the 7 back together just got a t2 transplant!!

Rebar works good and is cheap or free also i made insulator sleeves out of 3/4 pvc with holes cross drilled just slip the rebar into the sleeve and secure it ...I went through many of these as my tank was real bad...

xtremejimmy

iTrader: (1)

Once the electrolysis process is complete,is there any coating that had to be done inside the tank to prevent the rust from coming back? I haven't looked at my tank, but suspect I may be dealing with the same since the car has sat for so long.