Nissan Repair: nissan, fuel pressure regulator, spark plug wires

Question
i have s nissan 87 z24 motor i having trouble getting timing correct i get it close but cruises at 100 ks fine but accasionaly misses and coughs like its fuel but im thinking could be caused from timing plus chews fuel like there no tomorrow to go 150 ks and back 80 dollars in fuel any idea what my problem could be

Answer
Hi there, let's examine the timing first. The timing should be set at 3 degrees BTDC  and no more than 5 degrees and no less than 1 degree, unless it is specified on the tune up decal under the hood at 10 degrees BTDC. Always use a timing light and NOT a vacuum gauge as some indicate! If you cannot set the timing right: Have you removed the distributor or replaced the oil pump which is powered by the same as the distributor's shaft? Has the timing chain been replaced  and or jumped a tooth due to a loose or broken tensioner? Use a vacuum gauge to verify a late or early valve timing. Defective/leaky spark plug wires will cause some surging on the motor under load. Check those also.
Now the fuel. Causes for high fuel consumption are: Restricted or clogged air filter, Incorrect carburetor  settings, like float set too high, or over sized jets, a wheel or an engine component like the a/c compressor or a semi frozen pulley dragging, a faulty O2 sensor, an enrichment of the fuel mixture because of a vacuum leak, and in throttle body fuel injection, a faulty fuel pressure regulator, faulty O2 sensor, leaky injectors or even a faulty computer signal or no signal and all of the previously mentioned. I hope this helps :)