GothicBlade

Okay, here's the situation. My friend, (also on the board, BuddyRX7) is trying to buy a first gen here in san francisco.

Here's the deal: its a 1979, 12A, carburated (they all are, no?) owner claims the car only has 27k on it. We dont belive him. The odo only has 5 digits, we think its rolled over at least once. Maybe twice. First off, is there anyway to tell how many times the odo has rolled over? Is it recorded somewhere?

Also, it seems to have something wrong with the exhaust manifold. When it revs, instead of having a smooth accelleration sound, it kind of goes whum-Whum-Whum-whum... not an even note. Is that just a leaky gasket letting the sounds of the exhaust stroke out? It also backfires constantly, though nothing too loud. It also seemed to seriously lose power at high ends. Is that normal for a 12A?

I know nothing about carbs, but theres a slight smell of gas... leaky carb?

Lastly, theres some kind of hissing, whirring sound coming from the rear of the car.. sounds like rear left. I think its the fuel pump, but Buddy here thinks its something else. Any ideas?

On the plus side, the suspension is tight, all the struts are good... brakes need bleeding... body is very good for a 23 year old car.

Anyways, if you guys have any quick tips, I'd appreciate it.

GothicBlade

Oh, one other thing, it kind of wants to stall on idle. Gummy carbs?

RotorMotorDriver

iTrader: (1)

All 79-85 RX-7s are carburated, with the exception of the 84-85 GSL-SE's, which came with the 13B fuel injected engine.
You can try www.carfax.com.
Left rear...Sounds like the fuel pump to me. If it happens whenever the key is "on" (not necessarily when its running), its probably the pump. They can get noisy after so many years.
I would say no, its not normal. If anything, my car gains power after 5K RPMs...This could be caused by a bad fuel pump thats making noise *hint, hint*. I had a friend with an 85 GS that happened to. He thought the secondaries werent opening, but they were just fine. The secondaries stuck closed could also be your problem as well. Convert to mechanical and you'll have no problems .
Could be, or it could be just running too rich. It could also be a bad fuel pump.
The SA's (79-80) have a "thermal reactor" which is Mazdas version of a catalytic converter built into the exhaust manifold to take care of the emissions.
Could be something wrong with the emissions system like the air pump (Did they have these guys?), or even the thermal reactor, which might also explain your weird noise. Or, it could also just be running way too rich. Get a Racing beat header for that puppy and all is well .
Could be, or once again, could just be running too rich, depends on when it wasnt to stall...Like right as you step on the gas to go, or like just sitting there all by itself? Im not too good with carbs either, but I though it was worth suggesting.
Sounds decent man, I hopt it turns out ok for ya in the end. Theres lots of help here, you just need to ask . Im not an all knowing God like som people here, but this is what I would think if I were you. Take my answers as you wish .

~T.J.

GothicBlade

Okay, the reason Buddy thinks its something other than the fuel pump is the fact that it doesnt seem to make the noise when we're not going anywhere.

First off though, its his car. He dragged me along to check it out. I used to have an 89 TII... so thats why I'm here. (I have a 91 MR2 now, :-\ ) Anyways, rich running could be the issue. THe gas smell is a lot stronger after running at high RPM.

It also seems kind of dead at anything about 5500 or so. It will spin the tires no problem from a launch, chirp in second, give a good push into third... but in all gears, once you get it to 5500.. power just kind of fades off.

Anyways, about the exhaust, the owner claims an exhaust leak. It almost sounds like you can hear the exhaust part of the power stroke.. a whoosh whoosh as the rotor face goes by the exhaust port.

RotorMotorDriver

iTrader: (1)

Well, the initial power from the carb would be good if the primaries are working well. If the secondaries are stuck, you would be loosing power right about where you are talking about. I have mechanical secondaries on my car, and I can still spin the tires and chirp em and everything else without ever using the secondaries. If Im accelerating on the road, I rarely use the secondaries (keeps me outta trouble, lol). The car will pull hard till about 4K then let off cause Im not opening the secondaries.

~T.J.