I have changed the distributor and checked the timing with the advance off its in time at 4 btdc no vaccum leaks at all did the wd-40 test fuel pressure is low but just put a new pump on it even with the electric pump on it puttin out 7 psi it still pops gas back up the carb on the one side not both ??????????????
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something wrong here
with 99 degrees btdc it will not run
have you got it on the correct plug lead
next the timing is regulated by centrifugal advance if electronic or points and by the crankshaft position sensor if ECM controlled ( some after market distributors that are used in place of points units have a small sensor in the distributor that can adjust the timing according to engine rpms, but it cannot make allowances for mixture and so they can advance the timing but not take into account anything else which sometimes results in detonation under certain throttle settings
so initial setting for most cars is 10-12 degrees btdc at idle and with engine rpms set up to 3000 rms it may advance to 25-30 degrees depending on the advance mechanisms
with ECM units the timing is controlled by the crank position sensor and is set to parameters according to engine rpms and air/fuel ratio settings but it still has a basic 10-12 degrees btdc on starting
to fail smog tests you probably do not have a working cat converter and other problems besides timing
It starts up easy and idles good? And timing is at 10 BTDC? Sounds like you got it right then. I would check the fuel pressure at the fuel rail first. If fuel pressure is correct, maybe the throttle position sensor is bad?
Do you have vacuum advance on the distributor, or is it controlled by the ecu? If a vacuum advance device, maybe that is the problem. Beyond that, I don't know.
timing is a hair to advanced , did you set timing about 15 BTDC with vacuum advance pluged , any time it back fires out tail pipe its to far retarted, and to advanced pops out carb ,is every thing in distrubiter new or very good , points set correctly if you have them ,rotor and cap good ?
Sounds like you could have an aux air regulator valve, that is not
working when it will not work; there is no fast idle cold. Should be around 1500 rpm cold, the car will stall out and pop through the intake when bad. You have a digital volt meter to do some testing with to make sure the mass air flow is working correctly. Also, check the plugs for how they're burning, check the air filter for good flow, do a compression test and judge from there. Intake backfire is usually caused by running lean or improper timing.
For the 79 model zx, ignition timing was 10 degrees BTDC @ 700rpm For 80 and up zx, non turbo - 8 degrees BTDC +- 2 degrees @ 700rpm turbo - 20 degrees BTDC +- 3 degrees @ 700 rpm
Also done with distributor vacuum advance hose removed and plugged. NOTE: * BTDC = Before Top Dead Center * + - = Plus or minus
Hope thos helps; keep us updated.
IGNITION TIMING IS 13 - 17 DEGREES BTDC AT 650 - 750 RPMS. YOU NEED A TIMING LIGHT.TO SET TIMING FIRST CHECK FOR ANY TROUBLES.MAKE SURE YOU HAVE NO CODES. NOW TO SET TIMING.APPLY PARKING BRAKE AND BE SURE THAT THE CAR IS IN PARK.START AND RUN ENGINE UNTIL IT GET OPERATING TEMPERATURE.RUN THE ENGINE ABOUT 2000 RPM FOR 2 MINUTES UNDER NO LOAD,TURN OFF ALL ELECTRICAL LOADS, DISCONNECT THE THROTTLE POSITION SENSOR ELECTRICAL CONNECTOR,BE SURE THE ENGINE SPEED IS 700 - 800 RPM. REV THE ENGINE 2 OR 3 TIMES TO 2000 - 3000 RPM AND RETURN THE ENGINE TO IDLE SPEED.CONNECT A TIMING LIGHT TO THE NUMBER 1 CYLINDER SPARK PLUG WIRE AT THE DISTRIBUTOR END AND CHECK THE IGNITION TIMING BE SURE THAT THE TIMING POINTER IS POINTING TO THE 15 BTDC MARK ON THE CRANKSHAFT PULLEY,EACH NOTCH ON THE CRANKSHAFT PULLEY REPRESENT 5 DEGREES. IF THE TIMING IS NOT WITH IN THE SPECIFICATION, LOOSEN THE DISTRIBUTOR MOUNTING BOLT AND ADJUST THE DISTRIBUTOR UNTIL THE TIMING IS AT PROPER SPECIFICATION. TIGHTEN THE DISTRIBUTOR MOUNTING BOLT TO 10 - 12 FT LBS,STOP THE ENGINE AND CONNECT THE THROTTLE POSITION SENSOR.
Backfiring is a timing problem. It happens when one of the cylinders fires while one of the valves is still open. Your timing should advance as the rpm's increase. Carburated vehicle have what's called vaccum advance and if that vaccum advance line is disconnected it will cause what you describe. There should be a vaccum line that connects from the carb to the distributor that controls your vaccum advance. The sputtering at idle is also probably a symptom of a disconnected vaccum line.
Is the vacuum hose removed from the dist when the timing is being checked? Are you connected to the first plug wire (closest to the rad) on the drivers side? If this is being done.....remove the cap and rotor and check the springs on the mechanical advance,the advance should be tight to the shaft and springs tight. I would set the base timing on this set up .....at idle speed...... at between 5 and 10 before TDC.
Remember......timing marks on modified engines are not always accurate. Parts from this year and that year put together.
Timing should advance when accelerated. You have the vac on the distributor hooked to manifold vacuum. It needs to be on ported vacuum. And your base timing could be higher. I would set it at ten degrees.
Sounds like the timing is off. When looking at the distributor cap right next to it should be 2 wires with a plug at the end of it. Unplug it and start the car then check your timing . Make sure you mark the crank 10 degrees BTDC. You can bump it to 14 degrees BTDC if you like to gain 10 extra hp. After timing is set turn off car plug spout back in to the 2 wire outlet.(You have to unplug the 2wires in order to time a 5.0 the 2 wires control vaccum)
BTDC-(Before Top Dead Center)