jutta

Does anyone know an honest mechanic close within 180k of Huntsville that can help my 1980 RX7 get into good running shape. It's got ~60,000 original km on it since I bought it, but had been sitting in storage over10years. A local Mazda dealship got it running and certified last summer but after a carb rebuild it intermitently died on the highway. This summer I can't seem to keep the engine running to get it back on the road. help!!!

vipernicus42

iTrader: (4)

I don't have a mechanic for ya, but you should really read the Frequently Asked Questions thread

Q. Do you have an Rx7 you're trying to restore? A seized engine? a car that's been sitting for a few years? Wondering what the "ATF Treatment" is and how to do it without killing your engine?
A. Look here: Bringing a RX7 back to life

Jon

Edit: And for your problem, I'd say that either they didn't do that great a job on the rebuild of the carb, OR they rebuilt it fine but didn't drain the tank, replace the fuel filter and fill with fresh gas. In that case, the carb gummed right back up in no time. Sounds like your first steps would be to replace the fuel filter, drain and refill the tank, and put some carb cleaner in with that gas. Other than that, looks like it's time to rebuild the carb again, unless of course the problem is something else, like ignition.

Doc-Watt

Sounds like junk in the fuel line, or the fuel pump. On an older machine from your area of the country with high humidity, condensation in the gas tank causes rust which flakes off and enters the line. Start with a new fuel filter near th tank then check if the gas is pumping. Someplace to start anyway.
Doc-Watt

Doc-Watt

The ATF treatment is generally used in piston engines to free up sticky hydrolic lifters and remove other gums from the oil passages. Would not apply in general for a rotary, it may loosten up gum in the bottom of the pan though.
Doc-Watt

jutta

Thanks for the responses but I think I need to tell you more details so you can help me better. The fuel filter by the gas tank was changed last year before the carb was rebuilt. It ran great on the highway but then started quitting after a few long runs over 150 km. When the car died I thought the fuel gauge wasn't working and it was running out of fuel. Strangly refueling only allowed a partial fillup but topping up the tank got it going again. I also noticed a vaccuum when the gas cap was opened each time. This year when I started it up, it idled with the choke on but I couldn't keep it going more than a few minutes. The fuel pump was running ok, I wasn't pumping more gas in but when it quit the carb bowls were filled with fuel. Dad and I are wondering if there is something happen ing with the fuel pressure. Anyone experiencethis before. Does this still sound like a problem with rust interfering?

Rx-7Doctor

iTrader: (13)

You need to read some more before you make statements like this.
Marvel mystery oil or ATF, Prefeered is Marvel for dissolving carbon deposits and freeing up stuck apex seals.

Recommend you read the link also to educate yourself on how a Rotary works.

7aull

iTrader: (2)

jutta-
My 80 experienced similar problems:
-would run fine till about 1/3 of a tank, then start stalling out. It could sit (turned off) for a minute, then start and run fine for a mile or 2 then stall again. Ran great on a full tank.
-turns out the tank was "shedding" rust/gunk inside (from long storage partially filled that allowed an air pocket = condensation = rust). As the tank drained, the suspended gunk would collect and finally plug the pump line outlet.
-solution was to pull the tank, take it to a good rad shop and get it chem-dunk cleaned ($65), then use POR15's gas tank sealer kit (http://www.por15.com/bSPECIAL-Quart-...2&category=180) to re-seal the tank to corrosion protect it.
-pulling tank is relatively easy ONCE you drain it (!) 80 has no drain plug so you need to siphon as much as you can. Easiest way to do this is remove rear drivers wheel, remove plastic tank guard panel in wheel well,unscrew sender unit from side of tank and drain from there. Tank will be VERY tricky to manouver if there is much gas left sloshing inside!!! Only held in by 2 straps, but you need to disconnect filler hose, and finally the various (3 or 4) hoses that connect at the TOP of the tank. These can be released AFTER you drop the tank. NOTE!!! make sure you photograph/record which hose attaches where!!!
-obviously the fuel filter will need to be changed again - and should be changed at least ONCE a year.
-if you store the car at all (ie over 3 months), make sure the fuel tank is AB-SO-LOOTLEY full!! (tricky with 80s) and add fuel preservative.
Enjoy the car!
Stu Aull
8GS
Alaska

Jeff20B

iTrader: (13)

I'll only use Marvel Mystey Oil (MMO). It bought me some tuning time on my 20B before the rebuild. It didn't seem to kill the oil o-rings either. Oh and the spark plugs weren't ruined in the process.

I would have gotten bad results had I used ATF. It has no bussiness in or near a rotary (like an auto tranny - change to a manual). I wish the ATF myth would DIE.

hanman

I had a similar problem on my 80 a few years ago. It had to do with the gas cap. You might try replacing it and see what happens.

jutta

The carb rebuild specs and Mazda shop manual were double checked when the carb was rebuilt but when the float bowls were overfilling and flooding the carb. Adjusting the float numerous times did not help. Then the old needle valve was compared to the new needle valve and was discovered to be 2 mm shorter. The old needle valve (especially the rubber tip) was inspected under a microscope and determined to be fit to be restalled. The proper level in the bowls was able to be adjusted then. The car was run quite a fwe times on the highway but the gas tank levels caused some concern. The car stalled again with the carb overflowing in the driveway. This was now an intermittent problem. We were able to drive it to the garage last year for winter storage. This year we were unable to start the car and noticed again when the fuel pump was turned on that the carb was overflowing.There was noticable pressure in the gas tank when opening the cap.
We are thinking that the pressure could be the culprit and that the fuel pump delivers above the allowed pressure, overfilling the bowl. I will try loosen the filler cap to release pressure, open the air cleaner on top of the carb, and start the fuel pump only by turning the key to "run". If the carb barrels and bowl overfills and the fuel level in the sight window is high, we believe the Check and Cut valve have to be looked at. We have the shop manual and presumably the description for the procedure and related parts and hoses. Missing is the proper description of what this valve actually does other than perhaps venting the gas tank through the evaporation system into a charcoal canister. In the shop manual it states this valve "Except for Canada" so we have not been able to determine if there is such a fuel Cut Valve. Regarding the Check Valve in the return fuel line frm the carb to the gas tank to take fuel back to to the tank once the carb bowl is at the proper level. This valve and fuel line was checked. The explanation of the function is not clear.
If I can get the car to the garage, we think we will ask to have the fuel fiter replaced, have the Check and Cut Valves looked at, and have a pressure test done. Also the tank drained and flushed, checking for leaks. The fuel gage unit needs testing because it seems to give false readings. The brakes need inspection because the right rear drum clunks after sitting for some time. We had hoped to find a low pressure gage to do some testing ie: fuel pump pressure.
Any technical insights from thosr who have gone through this are most welcome!

jutta

Tahnk you 7uall,
I will look into the preserving the gas tank as you described. Any further ideas after reading my last post?