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New problems, same car!

on the honda civic, all is put back together and runs fine with no leaks!!!..but doesnt run for very long tho, on a cold start, you crank it and it fires up first time everytime, after warming up for about 5 minutes it cuts off all of sudden and its a bear and a half to start back up and have to let it sit overnight and start it up again and does the same day after day!!! before the stick of dynomite is inserted in the gas tank!!!

What do you mean by “all is put back together”? Without knowing what was done, I doubt you’ll get much meaningful help here.

Sounds like a cold start problem. Check for fuel system sensor failure or a missed connection. The initial cold fuel mix is rich until the engine warms up. It then switches to computer controlled lean mix. What is the year and mileage? What did you repair before this problem?

I have the same question as Lion does…what does “all is put back together” mean? Did you modify this vehicle? If so, how? Are you trying to run a different engine or a modified engine on the original ECU?

i first started off replacing the water pump, timing belt driven, replaced the gear and rockers and belt and cogs, basically rebuilt the whole front end half of the motor…i turned the engine by hand several times<apprx. 10 rotations> and it starts up and runs fine for about 5 minutes and then it cuts off with no warning and no check engine lite is lit when it is running…

Rockers? Did you replace the cam with one of a different rise or duration?

Main relay or ignition switch problem? Both are common faults.
You need to determine what is missing when the engine will not restart; fuel or spark.

If “cuts off all of a sudden” means it dies instantly with no sputtering then I would be leaning towards a lack of spark issue.
Make sure the ignition coil has power when the key is in both the RUN and the START positions for a beginning.

I would have suspected ignition too except that it keeps firing up again. My thinking is that when it gets warm enough for the oxygen sensor loop to kick in it can no longer properly meter fuel to meet the engine’s demands. I was wondering if a modification had been made that would require reprogramming the ECU.

OK4450, you’re one of my heros on engines. Does my theory make sense?

Did you drop anything on the engine when it was almost together. Look for broken or cracked things where wires plug into them. Broken stuff causes a lot of problems. Then, there is the possibility that you fixed it where it wasn’t broken.

no different cam but was going to replace cam next spring when i do a bore over .25 and put a bigger fuel rail on it