Car is using to much gas n back firing - 200SX Nissan Cars & Trucks

do you have any strong smell coming out of the exhaust end like gun powder? if you do so possible you have either broken or blogged catalyst. The other possible fault is most common the vacuum leak.

CHECK YOUR TIMING / PLUGS / PLUG WIRES / CAP N ROTOR / ALSO CHECK THE EXHAUST SYSTEM AS WELL BECAUSE IT MIGHT HAVE AN ISSUE WITH WITH THE OXYGEN SENSOR & AN EXHAUST PIPPING LEAK SOME WHERE ALONG IT.THERE MAY ALSO BE A BAD GROUND WIRE SOMEWHERE THAT MIGHT BE CAUSING AN ISSUE WITH IT BACK FIRING AS WELL.YOU MIGHT WANT TO CHECK THE GAS YOUR BUYING FOR IT AS WELL & ALSO USE A GAS TREATMENT THAT WILL CLEAN YOUR FUEL SYSTEM AS WELL.IF YOU STILL CAN'T GET IT RESOLVED TAKE IT TO A REPAIR SHOP TO HAVE A FULL CHECK OUT OF THE VEHICLE TO FIND THE EXACT CAUSE OF YOUR ISSUE.

You may have a failing fuel pump, the symptoms are that of low fuel pressure. The fuel pump is located inside the gas tank, the gas tank must be removed to access the pump for renewal. Remember to replace the filter and be careful not to create sparks and blow yourself up, seen it happen first hand.

I think you may have a carburetor problem.

Are you sure that it is getting gas, you can take a gas can and pour a small amount down the throttle body (just a teaspoon or less) and see if it starts to run while turning it over. Becareful with the air cleaner off you could get a back fire (fire!) so only use a small amount of gas and have a fire extinguisher near in case you get a flame up. Could be the distributor if it is loose (as it became in my 1988) the distributor hold down fork became bent from over tightening the bolt and it would not stay in position. You will have to slowly turn it if it moved (or use a timing light) to adjust it till it will run there is a connector near the brake booster that needs to be disconnected to properly set the timing.

Sounds like a fuel injector is clogged up or is not firing due to the computer not firing it. Check by putting a noid light on each injector and checking for pulse by viewing a blinking light from it. Also, one can check to see if a stethoscope can be used to listen for a clicking from the injector indicating it's at least pulsing that way.

could be exhaust manifold gasket

If it's got gas and fire then you'll have to go back over your timing, Somethingm is wrong there.

Have you checked the coils? It has three above the rear valve cover right?

sounds like you have spark plugs mixed up ever had them replaced