RB20 Swap won't fire up

[Frank300]

Thanks for any help in advance!

I have a '93 240sx, I swapped a RB20 engine in. New Engine harness/coil pack harness, ignitor, Cam angle sensor.

Engine has spark and good fuel pressure but fuel injectors don't seem to be spraying. Injectors are getting power though

Any clues as to what can be causing them not to spray fuel?

[Yellow4g63]

missing the 2 green relays near the ecu? bad CAS?

[baube]

engine cranks?


tried with maf unplugged?

mixed feed & return fuel lines on the rail?

[Frank300]

Originally Posted by Yellow4g63

missing the 2 green relays near the ecu? bad CAS?

Not sure which relays those are

[Frank300]

Originally Posted by baube

engine cranks?


tried with maf unplugged?

mixed feed & return fuel lines on the rail?

Yeah engine cranks, yeah also tried it with mad unplugged. Fuel lines are good

[SeizureNoodles]

I assume this car was running before the swap? What about after? Otherwise make sure your fuel pump is working. (You should hear a hum when you turn the key to the on position)

You can also try cranking, then pull a spark plug out to see if it is dry, this will confirm no injector fire. Or pull the fuel rail off and have it spray onto a piece of cardboard or towels when you crank the engine to confirm no injector fire.

Assuming you have no injector fire, I would point to the 2 relays near the ECU that you should have. One is for your ECCS and the other for your Fuel if I remember correctly. From the sound of it you probably at least have one. If you have both, try swapping them to see if you get injector fire. This is most likely your issue. Quoting research I just did, any green Nissan relay should work. It is the same relay that is in your Engine bay fuse box.

[Frank300]

Originally Posted by SeizureNoodles

I assume this car was running before the swap? What about after? Otherwise make sure your fuel pump is working. (You should hear a hum when you turn the key to the on position)

You can also try cranking, then pull a spark plug out to see if it is dry, this will confirm no injector fire. Or pull the fuel rail off and have it spray onto a piece of cardboard or towels when you crank the engine to confirm no injector fire.

Assuming you have no injector fire, I would point to the 2 relays near the ECU that you should have. One is for your ECCS and the other for your Fuel if I remember correctly. From the sound of it you probably at least have one. If you have both, try swapping them to see if you get injector fire. This is most likely your issue. Quoting research I just did, any green Nissan relay should work. It is the same relay that is in your Engine bay fuse box.

I have a Wiring Specialties harness so it has different fuses but those are working, my fuel pump does prime when I open the switch. I pulled out my fuel rail and it isn't spraying fuel from injectors.

[SeizureNoodles]

Did you ever get this figured out?

I would look for ECU diagnostic codes. Also you wouldn't have happened to buy this swap from a third party(not an importer) or the ECU seperate? I would imagine that an automatic trans ECU wouldn't pump fuel if it didn't receive the right signal... You can check if you have the right ECU with this list.

Skyline ECU Serial Numbers(how to know which ecu you have) - Nissan 240SX Forums

[baube]

pull the cas out, remove fuel pump fuse
turn it by hand with the key at "on" position

you should hear each injector click and have spark on each coil

if not cas maybe bad


also make sure all your engine grounds are good

[DRD]

My old RB would crank, fire, and die after one second of running. I could hear the coils fire when I spun the CAS. But injectors would not fire. What I found was corrosion in the ground distribution block in the harness. Usually located near the ECU. Its a large black connector that looks like it doesn't connect to anything and may be covered in tape. Don't remember how many pins there are, as it's been a few years for me since I had this issue. Anyways, take this apart with a small screw driver. You will see there is now a male and female part to this. Clean corrosion out and plug it back in, and hopefully this will help start your car.

[Yellow4g63]

RB20 DASH PLUG

BLACK/PINK-------------------- FUEL PUMP
YELLOW/RED------------------ TACH SIGNAL
YELLOW/GREEN-------------- VEHICLE SPEED SENSOR
BLACK/YELLOW-------------- IGNITION START SIGNAL
ORANGE/BLACK-------------- CHECK ENGINE LIGHT
TEAL----------------------------- AC RELAY
TEAL/RED---------------------- AC SWITCH
*NOTE*------ FSM states PIN #32/Check engine light as PINK/BLACK
But mine was ORANGE/BLACK

S13 WIRE/RB20 WIRE
SOLID/STRIPE

DASH PLUG WIRING

YELLOW/RED------------------- TACH SIGNAL------------------ YELLOW/RED
YELLOW/GREEN--------------- SPEED SIGNAL----------------- YELLOW/GREEN
ORANGE-------------------------- IGNITION START-------------- BLACK/YELLOW
*NOTE* The BLACK/YELLOW wire should trace back to PIN #43, which you might have read about on the other guides.
BLACK/PINK---------------------FUEL PUMP---------------------- BLACK/PINK
S13 wire found on the BROWN plug. RB20 wire found on the DASH PLUG.
I actually extended the wire from the dash plug to the brown to make sure it would reach
and plug in.
RED------------------------------ CHECK ENGINE LIGHT-------------- ORANGE/BLACK
BLACK---------------------------- GROUND