I have a 91 crx it sat up since may and I just put a d15b vtec in this past weekend. I sat the engine in and hooked up all appropriate connectors with the exception of two wires that is close to the intake manifold (yellow w/ green and a black) I have no clue where they go all I know is if you connect the wires together the main relay closes. But when I go to start the car you can hear the fuel pump kick in, the cel comes on for approx 2 sec then secures. The engine turns over and attempts to start and will fire for about 3-5 sec then stops firing and back to turning over. I replaced the spark plugs/wires, checked dist, replaced the map sensor and idle control valve. Im stumped can someone help
Travis

How many wires do you have going to the main ECM ground on the thermostat housing?

There is 4 wires 2 black, brwn/blk and blk/red

How many wires are going to your MAP sensor?

There is three wires yellow/ green/white and black

I'm at a lost, at this point. Do they come through the firewall? If so, where?

The wires come from the main wire lomb under a black box on the fire wall it looks like there is some sort of valve inside the box ill try to post a picture.

I couldn't get a picture but could it be the fuel?

There is a YEL/GRN that goes to main relay terminal 7, which provides power to the fuel pump. Remove your main relay and see if someone pulled that wire from the connector. The BLK wire probably was pulled from main relay terminal 2, which is a ground. These wires were either pulled from the main relay connector or were cut off from wires in the main harness.

Are you sure these two wires belong on the engine side of the firewall?
--------------------------------------------------------------------------
It looks like both of these wires go to the fuel pump. The fuel pump has a BLK wire (-) and a YEL/GRN (+) wire going to a 2P connector.

I was tracing the wires back and the go into the wire lomb that goes to the ecu. When I turn the car on I get a single blink out of the ecu? But where does the 2 wires go to is there a secondary fuel pump? The reason I ask is I
Turn the key to start
Let the pump prime
Start the car and it will run for a few seconds then loss of fuel pressure?

You have a problem with your ECM or main relay. Read Sections A and B in the link below:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-honda-civics-46563.html

Run the K-Test on your ECM and let me know what voltage you record at the MAP sensor connector.

How could it be the ecm or main relay the car will turn over and start but won't stay running? I'm getting no trouble codes. But where does the yellow/green and the black wire go to?

Why don't we begin by you giving me the results of the K-Test and the 3 diagnostic questions? Then, we can go from there.

5.4volts
The check engine light come on and then off after 2-3 seconds
You can hear the main relay click
You can hear the fuel pump prime
The two wires were for the thermostat sensor

Definitely no problem with the ECM or main relay.

Since you figured out where the two wires go, are you still having the problem with the car staying running?