jdm12a

iTrader: (3)

Its an 85 fb with about 85k on it 5spd 12a and for whatever reason it keeps redlining itself. The motor was running very crappy like only one rotor is firing but when you revved it up to about 2k or so the other rotor kicked in before. Now whenever it gets turned on it redlines itself no matter what and im not sure why. Sorry if i left any info out and thanks for the help

drittens

is your throttle stuck open?

trochoid

iTrader: (6)

Yep, check the throttle, choke, hot start and cruise control cables. If all of those have the required slack, check the return springs on the carb and the linkages.

rotarydude

iTrader: (2)

Stop smashing the gas pedal to the floor

LOL JK

jdm12a

iTrader: (3)

haha that actually made me laugh out loud a little. no throttle is not stuck open and i had checked all cables and they're fine. it started abut a week ago it would randomly redline itself when driving but i would kill the car and restart it in second and it would be fine, but now it constantly does it.

trochoid

iTrader: (6)

I don't know if a vacuum could cause that or not. I'd think the engine would die before it redlined. As far as I'm concerened, it's got to be in the cables, butterflys, or linkage/springs. Keep checking.

PercentSevenC

A similar thing happened to me a few times.

Occasionally when starting it would act like the throttle was full open, then fix itself randomly. The throttle linkage would seem fine (no binding, full range of movement, return springs appeared to be functioning correctly), I had no hot start assist or cruise control, and the choke was fine. It never happened during the day, so I could never see very well what was happening, and it hasn't done it in a long time. I really have no idea what could have been causing it. I thought I was going crazy, but it seems I'm not the only one!

Jeff20B

iTrader: (13)

I think on that carb it was the linkage for the vacuum secondary diaphram thing. It was disconnected for a while sdince the carb had the mech sec mod. Apparently the linkage must have gotten stuck on something. It stopped after I reconnected it.

Vashner

That happend to me once when it was freezing outside I had to turn off the key. After it warmed up never happend again.

trochoid

iTrader: (6)

Check out this thread, similiar problem, simple answer.

https://www.rx7club.com/1st-generation-specific-1979-1985-18/2500-rpm-idle-724743/

Kentetsu

Remove the air cleaner, plug any vacuum lines necessary when you remove it, then look down into the carb while someone else starts it up. Are the butterfly "flaps" open or closed. That will determine whether this is a carb issue, or a vacuum issue (which I highly doubt).

Check out the link that Trochoid posted, that's your most likely suspect...