So I have an 82' with a 12A. It had alot of prblems with plugging up the carb, so I cleaned out the fuel lines, tank and carb. I also checked spark (turned out the trailing plugs were not originally firing as well, this also got my tach working). Anyway, I finally ot it to fire, now I'm having trouble getting it to stay alive. It's very dificult to get started, and the engine acts like it's not getting suficient fuel. Sometimes it'll run like it should constantly, other times it'll hunt. Also, whenever I can get it idling for awhile, whenever I use the throttle at all, the engine dies. The accellerator pump workds like it should, I also replaced the fuel filter. I should also state that the car dies when I try to give it fuel from an external ource while idling (when it starts to hunt, in this case, carb cleaner) The engine is idling at 750RPM like it should (when it does finally idle).

Any ideas?

 

Is it possible I need to play around with the mixture adjust screw? Does anyone hae a pictre of it? I can't find the thing. I can find the fast idle and air adjust screw (or are they one and the same? They don't sem to be from the diagrams I've seen, plus the fast idle screw is a direct adjustment for the throttle plates whereas from the diagrams I've seen, the air adjust is and adjustable air bypass.)

Could it be posible that I only need to adjust the idle mixture? If so, could somebody please help me find the thing?

 

Hold on, looking through Mazda's manual it looks like there is no Air adjust screw after 1980. Is this the case? Is it just the throttle plate/fast idle screw and the mixture screw?

 

There is one. It is under a cover that can be removed. There are some picks on here in the FAQ section.

 

https://www.rx7club.com/1st-gen-archive-71/intake-carb-rebuild-how-strip-nikki-down-648376/

Remove #110, the adjust screw is under it.

 

Okay, so it looks like I mistook the mixture adjust screw for the Air adjust screw originally. It doesn't look like my carb has an air adjust screw, just the throttle and mixture screws.

 

Sorry, it only has the throttle and mixture screws.
There may be a way to adjust that but I don't know.

 

The older Nikkis have air adjust screws, and the later ones have a pressed in jet for the air. You really don't gain an advantage with the air adjust unless your engine is ported.

Can you go into more detail about what was plugged up and what you did to fix that?
Don't mess with your idle just yet. Idles don't go out of whack by themselves, and the fact that you've never had the tamper-proof cap off the idle screw and you can idle @ 750 tells me your idle circuit is fine.
This is something else entirely.

 

Yeah there is no reason to play around with the idle when it hasn't been played with before.

I personally would guess that its either your mixture needs adjusting, though if you haven't touched it and no one else has... then I would start looking for something else... otherwise you could do what I did until I finally got the right setting and carry a long philips or flathead around in the car adjusting the carb as you drive it and start it. Took me a while playing around between classes and after parking to get what I wanted.

More info though would be a big help?

 

Yup-yup!
The more info, the better. Sometimes one detail can make the whole diagnosis take only one post.

 

Well...a litte bit of everything was plugged up. My friend rebuilt the carb for that very reason, but it eventually became pluged again. Later he gae the car to me in return for getting his Supra running again (7M-GTE; popped head gasket). So, once again, I tookthe carb apart and cleaned it, got it running again; it got pluggesd again. To I droppe the fuel tank and lcean it, filtered the rust and ....mud out of the fuel as well (manually). I cleaned out the fuel lines while the tank was dropped, cleaned the carb again as well asthe fuel pump, and replaced the fuel filter. I used a water/lye solution to clean out the gas tank (there was ALOT in there to be cleaned out) I'd imagine not having a gas cap on it when I got it ha alot to do with the dirty tank and lines. (the base plate for the gas cap was acutally ruined; I replaced it witanother one from a parts car I have http://www.wanganmidnight.com/forum/...?t=2900&page=2) So...I drined the tank as best as I could (I have no money for a radiator shop to clean it, which is why I did it myself) I got most of it out, but not all of it; later the car would not run at al, and I found water in the fuel lines, which I since have purged from the lines and the carb (water is heavier then gasoling, s it should have all settled to the bottom of the tank and been purged by the fuel pump, right? I did alot to make sure all water was gone from the tank, so my best guess is someone put water in my gasoline by mistake where I was storing it).

When I first got the car to idle regularly, it idled around 3000RPM, I played with the throttle screw and got it down to around 750. It should also be said that there never was a protective cap on the idle mixture screw the entire time I've had the car (it seems to have had alot of owners as well...many of them stupid owners judging from the amount of stickers I removed from the car). Could it be that I just need to play with the throttle screw? I'l check my floats as well, to make sure they weren't messed with (don't know what my friend did, he also for whatever reason re-wired the fuel pmp using typical household appliance cors with wire nts and a groundside switch straight off the battery....I corrected that, too)

 

bump?