2001 honda crv b20b swapped no start. No spark no fuel help!!
 

Helpppppp!

welcome to the forum. have you reset the ecu? one way is to remove the positive and negative terminals off the battery, keep terminals away from the battery posts. place the two terminals off the battery together for 10-20 seconds and then reinstall the terminals one at a time. then try to start it. if it starts, let it run for 10 min or until the cooling fan turns on. ( do not let the engine overheat )

Yes the battery wasn't even hooked up for whole duration of the swap. I literally swapped out the old motor that ran and had spark and fuel for a new one and now I dont have any spark or fuel.

Update: check engine light dint come on at all when key is turned to on position. Rpms dont bounce when cranking and the main relay dont seem to be doing any clicking or getting any power. Like I said though everything was functioning before swap

did you get a chance to reset your ecu, it needs to learn your new engine. having the battery disconnected for an engine change is good and safe.

Okay, the first thing I was going to ask was if the check engine light comes on when turning the key to the "ON" position.
So, now need to determine if there is power and ground going to the ECU.
Need schematic to find pin out. Otherwise how to determine which pins to check?
See if ECU relays have power.
Next would be to check to see if there is a 5 volt reference voltage
Sometimes it can be shorted and shut down the ECU
TPS throttle sensor usually has a 5 volt reference

Wait, swapped out old motor for this one?
Same type motor? ECU?
Looking for compatibility issues??
Did new engine come with harness?

Sometimes connector pins get bent
Could check connectors for problems

Yes swapped in a lower mileage b20b jdm motor. Same thing just jdm. I used the original harness and original ecu. I checked to see if I was getting power to the 15amp fuse in the under hood fuse box for the ecu and when key is turned I dont get a 12volt reading. But the power coming from the battery into that fuse box is 12 volts. I have all brand new grounds and the g101 ground is clean and tight.

Sounds like the ECU isn't being powered up??
I don't have any schematics so it is difficult to tell you what to look at next.
Maybe an ECU relay??

Well that's my thoughts as well but I dont know of an ecu relay. Just a fuse in under hood fuse box. I know there is a main relay but that is also not clicking or doing anything

Check out the main relay.
If ground side switched then two hot and one ground
The fourth is the Switch.

Wait, did you say that the fuse was not getting 12 volts?

I dont understand what your trying to say? The main relay has 7 or 8 pins on it and is located next to the ecu. And correct in the under hood fuse box I wasn't getting 12 volts to the ecu fuse when hooked to a multimeter. But the power coming into the fuse box is 12v so idk what's going on.

I forget that Honda has a different type of main relay.
There is actually two relays inside
The ignition switch controls the power to turn on the relay to power the ECU
And then ECU controls the ground side switching energize the relay to power the fuel pump
So you have no power to the ECU or fuse
Which is why there is no check engine light which first turning the key to the "ON" position
Which tells me that the relay is suspect.

The main relay has 8 pins of which pin number 6 is not used
Pin 1 is to battery
Pin 2 is to ground
Pin 3 is to ECU power up
Pin 4 is to st. switch
Pin 5 is to Ignition switch
Pin 6 is not used
Pin 7 is to fuel pump
Pin 8 is to ECU control fuel pump

There are plenty of videos on youtube about the main relay issues.
Would do a little more testing before deciding to repair or replace part.
Good luck

If I remember right my number 4 pin is the one that isn't used cause I did pull it off to have a look at it. But I'll definitely look further into it just seems weird how it would go bad after I just changed the motor and wanted to do the initial start of said motor when it worked on old motor two days prior.

Yeah, it is strange. So this is why I suggest to look deeper into this before changing any parts.
Think pin 4 can just hang according to the schematic for the main relay. Not sure.
But, it should have 12 volts when trying to start engine

According to the internet, the main relay has known issues with solder joints cracking
However, since connectors were taken off and put back together, I tend to believe some pins might have bent.
But, I don't know. Please let us know if you find the problem.

I never removed the harness from the ecu just the engine. I'll be looking into it deeper today after work I've done many of these swaps and have never had this problem before so hoping to figure it out asap.