I have a 1991 Honda civic when I bought it it originally had a d16b1 engine in it but was only running on three cylinders so I did an engine swap to a d16b2 since it's the onle one I could find in such short notice I put this engine in over a week ago and have since put about six hundred miles on it so far. When I put it in everything worked fine it fired right up first shot and I havnt had any problems until a day ago it started and I drove to a store turned it off and when I came back it wouldn't start I was gone for maybe ten minutes and when I turned the key it would turn over but wouldn't start so I know it's not my battery or starter I had to sit there tryig to start it every couple minutes until after about ten tries twenty minutes it finally started it ran fine the rest of the day but after that exertions I turned it off it was off four atleast a half hour or longer then today I went to Fred meyers and got gas after I got gas it wouldn't start again this time for about a half hour or twenty minutes then it started and same thing ran great the rest of the day but everytime I turned it off it was off for atleast a half hour or longer again idk what's wrong with it everytime it has done this it has been on a slight downward slope and I mean slight just enough to were the car could move on it's own in nuetral could it be flooding out when I turn it off could it be because of te computer never beig changed from the first engine idk what it could be from please help as this is my daily driver and I need it also it's a stick shift if that matters

 

Intermittently cranks but won't start, you have to suspect the main relay. If the relay is not working you won't hear the fuel pump prime like it should when you turn the key on but don't crank. Also the CEL will come on and stay on instead of going on for the bulb test then going out.

 

what is the cel ho do i check that

 

Check Engine Light, on the dash the yellow light with the engine icon.

 

My chck engine light comes on everytime I drive but doesn't come on until about ten minutes or so after I start driving I'm thinking that it's my u2 sensor maybe idk my car ran great all day yesterday started right up everytime

 

To do that test, you'll have to wait until it doesn't want to start again. Then turn the key on but don't try to start, and watch the CEL.

Or you could take the main relay out and resolder it (instructions are posted everywhere, it's a common problem) and it's very likely you won't have the starting problem any more.

To find out why the CEL is on while driving, check the light on the ECU (Engine Control Unit, the engine computer). It's mounted on the inside of the firewall where the passenger's feet would be. Pull the carpet down and you'll see a window with an LED (Light Emitting Diode) behind it. Turn the key on but don't start. If there's a problem stored in the ECU, the LED will start blinking. It will blink a number of times, pause, and then blink again. The number of times it blinks between pauses is the trouble code.