I have a '85 rx7 12a carb. all bone stock GS. I have just bought it back after a couple of years and the damn thing just will not idle properly, we have had the carb off and cleaned, everything looked good so no need to RE&RE it. replaced the fuel pump because there seemed to be a block in the feed, now since that was done it has plenty of fuel BUT IT JUST WON'T IDLE! it was running pretty good yesterday and it now nothing. I thought pressure reg. but it seems to be working as it should, now spark is seeming a little weak, maybe my coils or distributor.
I'm really scratching a hole in my head with this one so any body have a clue
please help me out, I'd greatly appreciate it. Thanx again
ROTAX.

 

Does it run with throttle, does it miss at contant or decelerating speeds.

 

Kinda sounds like you have an ignitor going bad.....

 

Does it start ok?

 

No it doesn't start o.k. but it seems to have sufficiant spark, and I know it's getting plenty of fuel, and nothing was touched asfar as the carb after we cleaned it, like, we cleaned it, put it back on and it ran fairly well with the exception of the fact that it was bearly getting enough fuel to run @ idle, so, replaced fuel pump and here I am.

 

Check for vaccum leaks. If it runs good as long as you are giving it gas but dies when you let off that is a classic vaccum leak symptom. There is a large vaccum line just above the exhaust behind the carb. This line gets brittle from all the heat from the exhaust and tends to develop cracks and vac. leaks. Usually on the under side of the hose. I would check that one first. If that is not your culprit check all the ones around the carb. and "rats nest" solenoids.

Good luck!

 

If plugs are sparking, but weak, then your ignition system is probably good but you need to replace your plugs (and maybe cap/rotor). Vacuum leak is also a good idea to check for.

 

wooooo, i'm hoping the best for you, but i would check the compression after you search for vaccum leaks.