silverado1981

Does a 1981 RX7 fuel tank have a drain plug? Someone told me 1983 RX7 fuel tanks did have drain plugs.
Also, can I siphon gas out of my 1981 RX7 fuel tank? I tried sticking a siphon hose down inside the tank but something in the filler tube was blocking the way into the tank. Maybe there is a screen inside the filler tube to prevent siphoning?
Answers would be appreciated!

Richard Miller

84-85 has the plug from my observations. if you are dropping the tank anyways , remove the left rear wheel. remove the plastic shielding..loosen the worm gears for the hoses going into the tank. open filler door. remove screws holding the flange to the chassis. take a channel lock and gingerly work the rubber hose from the stem on the tank. don't bend the tube.

now you have access to the old fuel.

silverado1981

Thanks Richard. I don't want to remove the gas tank. I just want siphon the old gas out since there is no drain plug. Should the filler tube allow me to get a siphon tube into the tank? Or is there a screen in the filler tube to prevent siphoning?

Richard Miller

If you remove the filler tube/hose you can syphon the old fuel out. But, I would deeply have you consider dropping the tank and servicing it. its a few bolts to drop. and these tanks are quite old. I have done two tanks so far. I used KBS Klean and KBS Blast to clean and remove rust. I sealed my tanks with Caswell tank epoxy. It's a couple hundred into it, but you will not be fighting a rusty 40 year old tank. Also gives you a chance to replace the aged fuel hoses.

silverado1981

Thanks Richard but I am not going to remove the gas tank. Is there a screen in the filler tube that prevents siphoning?

Richard Miller

There would be nothing to block after you remove that filler hose.

odd question, does the pump work? Could you save yourself the trouble and just pump the stanky gas out using the pump.

Richard Miller

There would be nothing to block after you remove that filler hose.

odd question, does the pump work? Could you save yourself the trouble and just pump the stanky gas out using the pump.

silverado1981

So the situation is my car has been flooded for over 18 months and I've tried all the various technics (removing and cleaning spark plugs or replacing spark plugs, Type F down the front barrels, etc. etc.) I use to un-flood the car with no success. I've owned the car for 37 years so I've dealt with flooding at various times in the past but this it's been flooded for a very long time. I only fill it with 93 octane and always add stabilizer and ethanol shield to the gas. I called my local rotary performance repair shop and I told them I wanted to flatbed the car to them and I would, of course, pay them to get it to start. They told me they now only work on fuel injected RX7s and 8s. They hate carburetors and refuse to work them anymore - "too many headaches." Their advice was to drain the tank but I had the flooding problem 18 months ago before the fuel had a chance to go stale.

I've tried spraying carb cleaner down the front 2 barrels and then doing the cold start steps (as outlined in owners manual) but it still won't start even when the car is being pumped by another car. Btw, I can tell the car wants to start but it's just too flooded for too long. Now that you know much more about the situation do you still advise disconnecting the fuel line to the carb and trying to drain the tank that way using the fuel pump? Please keep in mind I don't claim to be a mechanic. I've just learned a few things over time so I know enough to be dangerous.

Maxwedge

iTrader: (1)

Not sure I can help you but here's some thoughts:

On my '85 I can push a 1/2" hose down into the tank no problem. I haven't heard of an anti-siphon screen before. Maybe twist the tube as you push it down, to help work it around the bends.

Your tank is old and has some amount of gunk and corrosion in it. Check your stock fuel filter for sediment block. And if you remove the fuel hose at the carb and put it into a bottle, you can turn the key and see if you have fuel flowing to the carb (to rule out a clogged line).

Your wasting your money on premium fuel. High octane is only needed by high compression engines ( turbo or supercharged). Higher octane actually makes the fuel less-flamable so it doesn't ignite early from the higher (forced) compression of the turbo. Has absolutely zero benefit for a low compression car like yours.

If your engine has sat still for the past 18 months, and is truly flooded, you might have bigger issues. That fuel has been degrading all the seals in the motor.

If the car hasn't run in 18 months the carb might be gummed up.

Your rotary shop sucks.

midnight mechanic

>you can siphon
>fuel pump to pump the gas out (I did before)
>pull the hose off the fuel pump that comes from the gas tank (I had a leak in that hose, and it did a great job of emptying the fuel tank).

Carburator problems>>>---->Gum Out Carb Cleaner, Gumout ® Fuel Injector & Carburetor Cleaner, Red Line Complete S1-1 Fuel System Cleaner
>>>you get the idea, use every fuel/carb/injector cleaner until you find one that works<<<

mazdaverx713b

iTrader: (91)

Honestly, if the car has been sitting for a few years, you may want to consider rebuilding the carburetor. Especially if it hasn't been done previously. You need to verify if you have proper spark and tach bounce when cranking. Pull the cap and inspect the contacts in the cap and inspect the rotor contacts for wear as well

Pull the fuel feed hose off of the carburetor and put it in an empty water bottle. Crank the engine and see how much gas pumps into the bottle and the condition of the gas. This could save you a lot of time in siphoning gas from the tank should the fuel be ok. Its likely not ok but will verify that the pump is working properly and give you an idea of what you're starting with.

Spark plugs...How old are they? Are they NGK BR8EQ-14's? If not, they should be. This should give you an idea of some of the basic things to check to start.

Ckforker

You're wasting money putting 93 octane in your car. These little engines like regular pump gas.

Id do what others have said, use the existing pump to empty the tank. It's already at the lowest point. If you've been using fuel stabilizer, I'm not sure what you're going to accomplish just draining the tank. Flooding would be much more carburetor related.

silverado1981

Thanks! Where is the fuel pump located?

silverado1981

Thanks. I replaced the fuel filter a few weeks ago. Regarding 93 octane, I was told it burns hotter and therefore reduces carbon build-up. And supposedly 93 does not degrad as fast as 87 octane does. So that's why I have been using it. I could be wrong. Will try removing fuel line at carb.

RX7_Renesis

iTrader: (1)

The fuel pump and filter are located under the chassis on the left side of the vehicle .. just ahead of the rear wheel.

silverado1981

Thanks. I will inspect contacts and fuel as you recommended. And those are the plugs in there now. They are basically new since the car has never started since I installed them 18 months ago. They are just wet every time I pull them out - and then I dry them off and go through the de-flood procedures.

silverado1981

Ok thanks!

Maxwedge

iTrader: (1)

Yes. The pump is mounted behind (on top of) a protective plate. It's right next to the stock fiel filter. From the bottom you'll see something like this...

It's mounted with 3 bolts. Take it loose and the little pump is on the upper side...

Even with the visible surface rust mine wasn't dificult to remove. Good luck.

silverado1981

Thanks! Good to know where it's located. My fuel pump may be the original. Btw, the car has 132K miles on it.

Ckforker

I would buy or have on hand some hose length and a way to connect it so you're not under the car when you hit the key. Also have enough buckets to capture all the fuel.

Fortunately it's a low volume pump, but it still comes out pretty quickly.

Of course have a fire extinguisher close by. I'm just paranoid about fire after my sister was badly burned in high school.

Maxwedge

iTrader: (1)

Yeah no problem, I took mine off when I installed the RB Holley and needed a bigger pump. It didn't fit under the little skid plate so this has been on the shelf for a few years. Just wanted to show you what you're looking for.

I still use the OE fuel filter though, because it works and is available, and is "clear" so you can see any grit in it.

Fuel stabilizer only lasts so long. I put it in all my yard equipment before winter and If I skip using my hedge trimmer for a year it's a real bitch to start the second year. I'd think 18 months = bad fuel throughout your system. And varnish (the thick gel/gunk left over when gas evaporates) is pluging things up. Particularly the carb. Get rid of your old gas (as you are looking to do) and try fresh gas and injector cleaner as others suggested. That's a good start.

Make sure you have good spark at the plugs. Fuel/Air/ Spark (Air being the easy part). A carb rebuild is probably due but make sure you have fuel pumping to it and strong spark before you go deeper. I don't have the years of rotary knowledge of some of our long-time members but I try to K.I.S.S. (Keep It Simple, Stupid). AKA: start with the basics. You got this!

silverado1981

Thanks! Yes, the new fuel filter I put on recently is clear like the OEM filter I took off. But should try to drain the old fuel out at the carb or at the fuel pump?

Maxwedge

iTrader: (1)

For simply draining the tank I don't think it matters. But if you dump a few bottles of Fuel Injector cleaner in the tank and pump it all the way to the front, it will help clean all the plumbing before the carb.

silverado1981

Thanks! Why fuel injector cleaner? Will that clean out deposits in a fuel line and any varnish there may be in the tank? What brand injector cleaner do you recommend?

Maxwedge

iTrader: (1)

I don't have any favorite. Any fuel system cleaner from you local auto parts store is a good start. They are all designed to disolve gunk and solids left behind from aging fuel.

Gunk/rust in the tank is a different story. All factory gas tanks will devolop rust and loose paint over the years. Our cars are 40 years old and (almost all) have spent most of that time sitting parked. My current car had 59k when I bought it in 2018. If it had been driven and serviced regularly in those 34 years I wouldn't have needed to replace all the dry-rotted rubber hoses / gaskets / bushings / shocks / weather stripping / etc etc etc.. "Low mileage barn find" is total BS for everything except rust. Everything else on those cars is trash after 30-40 years.

Sorry, where were we? Oh yeah. Fuel problems, whether rusty tanks or gummed up carbs, are a Major issue with these cars because the survivors are examples of cars that weren't driven much. Most cars get driven 12-20 thousand miles a year and traded in when they hit 100k. Our low- mile cars are essentially "neglected" because they sat more than ran. And while that's great for sheet metal, it sucks for anything rubber, plastic or fabric.

1st gen RX-7's are the first cars designed AROUND the Mazda rotary engine. Not the RX-2, 3, 4, or 5. The Cosmo yes, but.. that was a design exercise and not a real production car. You'll staighten out your fuel system and then be driving your Living Legend sports car again.

Living Legend.
Halo Car.
1st gen RX-7.

You got this.