OK, so an update to this thread - https://www.rx7club.com/1st-generation-specific-1979-1985-18/eliminating-cap-rotor-some-failing-ignitor-pointers-919318/

This is a different issue but same car and some history so we know whats going on ignition wise.

Carb is a emissions removed un-modified Nikki.

When car is in neutral and parked I looked into the carb and can visually tell that the rear primary is getting less fuel than the front. If I unplug rear ignition the car stays running although doesnt accelerate as good as when its hooked up. If front is unplugged then engine dies and will not start.

The engine sounds like it is running on only 1 rotor but it seems that it is running on both just very lean on rear. Here's where it gets interesting - when the RPMs go up enough for the secondaries to kick on the engine takes off and has decent power. It also sounds much better as well. Both secondaries seem to be spraying same/similar amounts of fuel.

Compression test has been done and both front and rear are strong and even on all sides. I guess my main question is other than the fuel jet being clogged what else COULD cause less fuel going into rear. Floats are set correctly and everything seems to work just fine other than low rpm operation (which is obviously needed). This carb has actually been rebuilt once and tore down and cleaned 3 or 4 times (kept having carb issues in the past, trying to make sure nothing carb wise was wrong).

I ask about anything other than fuel jets in case I missed something. I know if an air bleed is clogged it can cause a rich condition just wondering if anything else is clogged would it cause a lean condition (other than fuel jet). I want to make sure and check everything I need to before I tear it down, yet again...

Thanks in advance for any tips.

-IanS

 

Could it be that your shutter valve is sticking? Did you check the plugs? Are the rear ones white and the front ones brown/black?

 

A clogged jet would be the primary suspect, but since that's also pretty obvious I will simply assume that this has been checked and eliminated.




.

 

Could be the rubber emissions hose down low on the rear secondary runner. These like to get hard and cracked so near the exhaust. I don't recall the name but you probably know what I'm talking about.

 

Thanks for the ideas guys. Once I get a chance to tear it apart I will let you know how it goes. Honestly we've had nothing but issues with this carb. Of course, if the owner stopped messing with it all the time it probably wouldnt be such a pain in my ***.

 

at the dealership we either called it the mystery hose, or N201-13-756A....

since we're near the subject there are one of two things going on.

1. there is a problem in the FUEL delivery, like a clogged jet/passage etc

2. and the more likely, there is an AIR problem. if there is a vacuum leak on the #2 rotor, or something like this, then the engine will suck less fuel from the carb. there are air passages in the intake that go form the intake to anti backfire valves and things, these can be HUGE leaks, but they won't show up to the outside, so you can spray brake clean all over and not find it.

i had an 83 LE i rebuilt the carb on TWICE, because the air pump came apart and the pieces jammed one of the valves.
i've also had a carb that REFUSED to meter fuel in the idle circuit, the fix was changing out the metering block, even though all the passages worked