Hey guys,
My 79 RX-7 just recently developed an idling problem. I had the engine rebuilt last fall,and when I installed it again it ran great. A few weeks later it was stalling when I came to a stop sign,and the engine was dropping back to idle. It would fire right back up,and would do it again when dropping to idle. I thought instantly vacuum leak. I didn't have any time to look into it,and the next time I drove it it was all fixed. Fast forward to Monday,and I am driving it,and it does it again,and it hasn't magically fixed itself yet again. I had TR8Todd over to help rev the engine while I sprayed carb cleaner around the engine looking for a vacuum leak. The problem is the clutch fan blows the carb cleaner all around,and I can't locate an vacuum leak. Can I remove the fan for a little while to help locate this leak? Am I chasing my tail with a vacuum leak? Todd thinks it is a carb issue,but I never changed a thing on the carb,and it runs great otherwise,so I doubt it. Any help would be appreciated.
FYI the engine is a stock 79 12A running Racing Beat header,and streetport exhaust system,83 Yaw Power modified carb. I have not changed a thing from before when the car ran great,but I had a oil control seal of two dry out,and caused the engine to smoke something fierce. I am leaning toward a vacuum leak as I have experienced the same conditions before,and that is what it was,but maybe you guys who are way smarter than me can tell me otherwise.
I had one do something similar, it would not idle properly once warmed up. It turned out that the idle passages in the carb base plate were clogged. On that one, whatever was clogging the ports would not come out so I wound up getting a base plate from another carb, that fixed it right up.
While checking for vac leaks, you don't have to remove the fan. Cut a piece of cardboard to hold between the carb and the fan and spray away.
Change the plugs. I spent a month chasing what I was sure was a carburetor problem. Rebuilt twice, adjusted, and tweaked until I had the carburetor all screwed up. Changed the plugs, spent the weekend resetting the carburetor and it rung fine now. Before I touch a carburetor now I swap in a new set of plugs. Especially on a rotary.
Sounds like the idle issue I'm having with my FC. When I start the car cold, it will rev up to 3000rpm for four or five seconds (normal for an FC), but it will slowly rev down till it stalls unless I give it a little gas. Two minutes after, the idle will oscillate between 1500-2000rpm for about a minute. Once the engine is warm, it will start and idle normally. I FINALLY found a shop that will take used antifreeze in this town, so I'm going to remove the upper intake manifold and start replacing vacuum hoses, which I've been putting off for months.
In reply to Toyman01:
Hey Toyman the plugs are new within the last 2-300 miles,and they are good NGK units. I still think it is a vacuum leak,but I don't know for sure.
Back from the dead post. Finally got around to pulling the carb off(super easy just needed time),and popped the top off,and guess what? The float bowls are full of some sort of gunk that is plugging the hole in the bottom that I assume is the idle circuit,or idle circuit related. I plan on pulling the carb apart one piece at a time,and cleaning it all up with carb cleaner,and going from there. I also flooded the engine on Friday trying to get it running for my yearly inspection. I got it going good enough,and passed inspection,but I think I need another set of plugs unless you guys can tell me an easy way to clean these up so they are so gross looking.
On a side note when driving to the inspection station I was hearing this god awful noise from the left front wheel. It is amazing the wheel didn't come off as all the lug bolts were loose. So loose in fact that I got a good 4 or more turns out of each one before they were snug. I got really lucky!!
Chris
Might be worth to have the carb cleaned with an ultrasonic cleaner once you blasted it with carb cleaner. They're pretty good as dislodging deposits in those small passages...
Sandblast the plugs? Hmm never thought of that. They are brand new within the last 3-500 miles so they should be salvageable.
Where can I get it ultrasonically cleaned?
Anyone have an idea where the holes in the bottom of the float bowls that were plugged up on my carb go to circuit wise? I ask becasue I want to know that I cleaned it out good enough so I won't have this issue when I put the carb back on. They look like the some how travel to the carb base plat,and maybe expel fuel after the throttle plates,but I could be wrong. Any help would be appreciated.
Got the carb all cleaned up over the last few days. Got it back on the car today,and viola it idles!!! Still messing with the idle speed,but it is holding at around 8-900 pretty steady. It is so nice driving it again. If only the RX-4 was this reliable.
