Hi everyone, i have a Ef honda civic that will not start up. it will not crank at all
and when it do crank it will fire up for a while until it auto shot down again, Alternator and starter are new, Battery new. cant figure out what's the problem. any help?

 

Going to be tough to diagnose that one with the sketchy information given so far. Won't crank at all...but then it does? Maybe starts sometimes, but doesn't stay running? LOTS of possible suggestions here, but we need more specifics to give you any useable help.

If nothing elses, start with the very basics. You say you have a new battery, alternator and starter...but are they GOOD and are they installed correctly? Run through this list and see if you make any progress:

1. Test battery. Use a digital multi-meter to read voltage and see if it is fully charged. Also, a good auto parts store can load-test it for you.

2. Make sure battery cables are in good condition, CLEAN and TIGHT at both ends.

3. Inspect wiring to starter and alternator. Make sure wires are not frayed, connections are not corroded and that all hook-ups are tight.

4. Check for clutch switch (manual) or neutral safety switch (automatic) failure or mis-adjustment. I can't even count how many batteries, starters and alternators I've sold to customers who failed to check this simple item!

5. Ignition switch. Check it for proper engagement and function. If it looks to be working right, check it for continuity with your $5 multi-meter.

The above items are possible things to look at for a no-crank or intermittent no-crank scenario. Below are a few other things you may want to look into if it starts but won't stay running:

1. Fuel pump operation. Is the pump activating, and does it stay on? A faulty relay or pump could be the culprit here.

2. Fuel pressure. If the pump appears to function, check pressure at the rail with a gauge. Weak or erratic pressure readings spell trouble within the fuel delivery system. Check the pump and regulator.

3. Fuel filter. Really...you HAVE changed it within the last 5,000 miles or two years, haven't you?

4. Ignition coil. Check for spark output and inspect connections. Again, most parts stores can check electrical components for you if you have any doubts.

5. Catalytic converter. Rarely happens, but a plugged converter will cause hard stats, no starts or stalling soon after starting. I've seen it on a few occasions.

6. ECU problems. Have it checked and declared 'good'. Not all that common for them to go "bad", but it does happen now and then. (Mitsubishi owners know this very well...far more common on them).

Like I say, without more input from you...all we can do is take a few wild guesses, but hopefully these ideas help get you moving in the right direction.

 

Yeah man, more info will would help us help you....one more thing I'd check is the main relay.