Nissan Repair: 86 nissan pulsar bad mileage hunting idle, 1986 nissan pulsar, air filter oil

Question
Well i have an 1986 nissan pulsar canada model (that means no ecu, no o2 sensor) and its carbureted. i've rebuilt the carburetor with all new gaskets, new needle valve, etc. It seems to want to stall out at idle if I adjust the idle to where it should be in gear (650RPM) I have to turn it up to about 900 -  1000 RPM in gear to keep the car running. Also, it only gets about 10MPG, long ways away from the 26 its suppost to get.

I have changed the fuel filter, air filter, oil filter, spark plugs, plug wires, distributor cap, rotor. Checked the EGR valve, its operating fine, and i suppose the fuel pump is fine, because it drives really nice, has tons of power for a 69HP car.

The emissions label and the shop manual say to set the timing at 5 degrees after TDC with distributor vaccum advance disconnected. I've done that, and it seems to lose power, and stumble a bit at 3000RPM driving, and fouls up the spark plugs. So i set the timing before TDC about 7 degrees BTDC and it runs nice. Mileage is a bit better BTDC though.

It also failed the emissions test. high CO%. 8.56%, should be about 1.25% from past results. The NOx is also really low (about 120ppm) way lower than it was a few years ago (1700ppm) but they say that excessively high co like i've got can play around with the testing device masking the NOx.

Today i checked the evaporative carbon canister, and disconnected the line to the intake manifold (could be called the purge line) and the car wouldn't idle at all. It would stumble from about 2000rpm right down to a stall out. So I've plugged that hose. I also sucked on the purge line (if its called that) the manual says its suppost to hold a vaccum, but it didn't. Seems like the valve is stuck. Could this be sucking twice the amount of fuel from the tank?

I've plugged that line for now, and gas mileage is a bit better, no where near where it should be. seems to run better now, and the spark plugs are a lighter grey color, a lot better than carboned up and brown. That might have been related to a rich mixture when the timing was set to fire ATDC.

Any ideas on what might go wrong? This car is carbureted so there isn't any MAF sensor or anything. No air fuel solenoid in the carb either.


Answer
James,

There is an electronic power valve that needs replacement.  It is flooding the engine and that is the cause of your problems.  Look for the electrical wires and it looks like it is made of brass.  If you rebuilt the carburetor you probably remember seeing it.  It screws in and you just replace it and then reset the carburetor to idle without all that extra gas.