NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   -   newbie to carb'd 12a....rotaries in general. (https://www.nopistons.com/1st-generation-specific-16/newbie-carbd-12a-rotaries-general-64868/)

85GS12a 03-21-2007 07:11 PM

i'm wondering what i could do on my unmodified 12a? the carb isn't letting any fuel in, and i have no clue how to work with it, i'm normally a domestic guy, but i finally found a first gen RX-7 and i'm really excited about getting it on the road.



i'd use the stocker if i could get it to work, but i don't know if that's even possible at this point, as i have no clue on earth how to fix it other than a different carb.



i've owned numerous 2nd gen and 3rd gen rotary cars, but this is my first carbureted first gen.



i know you guys know your ****, i can tell by reading some of the threads. any help is truly appreciated.

flight_of_pain 03-21-2007 07:21 PM

if the pump is functioning and supplying fuel to the carb then check under the banjo bolts next. on top of the carb there are 2 banjo bolts that the fuel inlet goes to. take these out https://www.nopistons.com/forums/pub...IR#>/smile.gif around them is a small mesh screen that often collapses or fills with crap, thus blocking fuel flow. once you have the bolts out, its a straight shot into the float bowls, clean those passages as well.





isaac

85GS12a 03-21-2007 07:40 PM


Originally Posted by flight_of_pain' post='864720' date='Mar 21 2007, 07:21 PM

if the pump is functioning and supplying fuel to the carb then check under the banjo bolts next. on top of the carb there are 2 banjo bolts that the fuel inlet goes to. take these out https://www.nopistons.com/forums/pub...IR#>/smile.gif around them is a small mesh screen that often collapses or fills with crap, thus blocking fuel flow. once you have the bolts out, its a straight shot into the float bowls, clean those passages as well.

isaac







i removed those, fuel gets to them, but i believe they may be either collapsed or clogged, i'll check that out later.



so that would be the most likely excuse for why it does this? if i remove the screens and everything works well, then i should obviously get some new ones.





thanks!

partly mazda 03-21-2007 10:41 PM

try tapping on the top of the carb to unstick the floats,,have the key on(pump running) watch and listen for the fuel to fill the float bowls. there are sight glasses. stop before breaking the carb.

flight_of_pain 03-21-2007 11:12 PM

if you check the filter screens and they are ok, move to the floats/needles next, with the banjo bolt out you should be able to sight down and verify that the float needles are not stuck up in the seat(i have seen this before), if that is not the case remove the center bolt (the one the air cleaner bolts to) and the 7 top bolts on the carb, remove the top and inspect the floats. i have seen the rod the floats pivot on rust to the float arm/carb body on carbs that have sat for a long time.





isaac

85GS12a 03-22-2007 11:25 AM

it ended up running last night, although it's just dumping fuel in rather than spraying it in like normal.





i'm kinda upset with this thing, the carb. is probably junk since it sat for over 2 years....

flight_of_pain 03-22-2007 08:09 PM

the stock nikki is actually one of the easiest to rebuild carbs ive ever encountered. you would probably be better off just pulling it off of the car, tearing it down and cleaning everything. it sounds like there is crap in your float bowls.





isaac

bigboi12A 03-24-2007 08:09 PM

relax listen carefully to these guys. A nikki properally modified can be a lot of fun. I dont know if u live in a state where they dont do emmissions if so your in luck. Get a header loose the cats and ripp of those selinoids and rats nest and your car will run mutch better.

85GS12a 03-26-2007 10:49 PM


Originally Posted by flight_of_pain' post='864890' date='Mar 22 2007, 08:09 PM

the stock nikki is actually one of the easiest to rebuild carbs ive ever encountered. you would probably be better off just pulling it off of the car, tearing it down and cleaning everything. it sounds like there is crap in your float bowls.

isaac





i'll see what i can figure out, how easy is the carb to remove frin the intake, or is it just easier to remove the top and go from there?



this thing has a chitpotload of vacuum hoses...i'll have to try and figure this out, it will be a new experience either way.



i do have an LT1 sitting here with tranny, wiring harness, EFI, everything needed to make this RX fly...and i can make an LT1 run, SBCs are pretty much my specialty, and it's been said that there's only a 150 or so pund weight difference in the rotary and the LT1..although i'd rather run the rotary if i can make it work, just cause i love the way they rev and sound.

Buzzbomb 03-30-2007 10:02 PM

I say remove the carb, and send it off to someone who knows their stuff. I was going through these same problems, and was about ready to give up. I took it to a guy who used to rebuild carbs at a local Mazda place. Three days later it ran super smooth and no more headaches.



The carb I was having the problems with was a "rebuilt" one from rx7goods on ebay. Don't do it! It had bent needles, cracked floats, etc etc... In other words, I got screwed. The dead giveaway was opening the box to bent brackets, bent mixture screw, and other damage so bad I had to use the parts off my carb.



Bottom line, if the car has sat up for that long, a rebuild is probably in order. Gas turns to gummy varnish. It was so bad I had to replace my entire fuel system from back to front. Well, except the hard line;),,,,BB


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