12a Won't Rev past 6k RPM
 

For some reason, my 12a won't rev past 6k, starts losing power at around 3-4k and sometime misfire, what could be causing those issues?

The first thing I would check is for blockage in the exhaust system from a faulty catalytic converter. They are known to break down and will cause a huge power loss and issues with the engine revving.

That's what I thought, I'll try to find someone with a ramp or something that will let me have enough space to unbolt the cat to the headers.

What size are those nuts btw?

Check the carb vent solenoid. If it's bad it can cause all sorts of weird issues. Mine died and it did the same sort of thing. Does it bump/missfire while at constand speed?

I checked my cat today and the cat and it doesn't seem to be that considering that even at high revv, there's a normal amount of exhaust velocity.

Me and a friend of mine played around with the car a bit longer and he tried to block the intake of the carb to see if it would make me lose power but I barely lost any more power (Engine would rev till 5.5k rpm instead of 6k) which leads me to believe that it's a fuel problem, so either the fuel pump or fuel filter, would I be wrong for assuming that?

Got any picture of what a carb vent solenoid looks like in the 12a?

Also, where's the fuel filter on the FB?

Could also be that the secondaries aren't opening....but if you are convinced it is a fuel issue, change out the fuel filter under the car if you haven't done so already.

The vent solenoid will cause what seem like fuel issues. It's located on the drivers side of the carb by the fuel lines. It has a single electrical connector and should have power once the key is in the run position. It will make an audible click when it turns on and off. The fuel filter is a canister located by the fuel pump, infront of the left rear tire under the vehicle. You don't have to remove any parts to get to it. When you replace it, make sure you have the filter facing the right way; it can be checked by just following some of the fuel lines.

Have you checked the fuel bolws yet? The fuel should be halfway up the glass. DON'T mess with float levels yet.

Yeah I'll go change the fuel filter this week, probably tomorrow. Just to be sure, is there a specific fuel filter I should get or I can just go get a fuel filter at autozone?

I haven't had the chance to check the secondaries but it does make a lot of sense as well.

I'll go check the solenoid tomorrow at the same time as the secondaries!

I'm not familiar with the fuel bowls, what exactly is it, what does it do and where is it located?

Errr.... Simply put, fuel/float bolws are what hold the gas in the carb. They are controlled by needle valves and floats to keep the right amount of fuel in them. If the levels are off or they drop/flood under certian circumstances, literally everything else in the carb is thrown off. There are two sight glasses on the carb: one in front and one in back. The one in back requires a mirror to see. Fuel should be at the middle of the glass at idle.

I'll try and get a picture of the solenoid later.

The vacuum-operated secondaries do not open unless the engine is under actual load (as in pulling hard), which makes testing them with the carb on the car kind of difficult. Testing the diaphragm usually involves pulling it and using a vacuum pump to see if it reacts to, and holds, vacuum.

Just revving the engine under no load past 6K does not require the secondaries to open, especially if you increase RPMs at a moderate pace.

When he says he starts losing power above 3-4K that implies he was under load. Not easy to test secondaries in the driveway, but doesn't mean that isn't the issue he is having. When they are stuck closed, the car is anemic right above the level he was having issues.

I have a shop that specialises in Rotaries close to my place, should I just go there to see if they can figure it out at that point? How much should I expect them to charge?

The car seems to also be revving rather slow... I would also check for spark and compression... I think it could be running on one rotor

The car is definitively not running on one rotor and the spark plugs all seem to work fine,

Could it possibly be an issue with the carb?