RB20DET in s13, no spark but fuel.

[oXeNo]

I just dropped a rb20det into my other 240 the other day and just finished wiring everything up and tried starting it. The fuel pump relay clicks over and the pump primes. But I have no spark, I can feel the motor just turn over with no spark. From what it sounds like only the fuel pump relay is clicking over and not the ignition one. What could this be? I am trying to get this started so I can properly test my compression. The CAS is plugged in and I double checked the wiring, I made sure all the grounds are bolted in right. This has got me so stumped. Also when turning over all I hear is the relay rapidly clicking if that is any help. This is the most confusing thing ever lol.

[budderigs]

it sounds like you might have wired either.

a:the ecu relay wrong

b:the dash plug wrong
or
c: other(tbd after diagnosing the relay clicking.)

if your fuel pump is turning on the ecu relay is working. the ecu relay turns on first then the fuel pump relay is turned on by the ecu.

my first guess would be your ign switch source is one that cuts power when your ign is turned to the start position(example. when your turn the key to the start position it in turn turns off the computer)

the easiest test I can think of off the bat. try turning your key to run make sure the fuel pump primes correctly(3 seconds then stop) check the lights on the ecu they should flash some sequence(at this point it doesnt matter what they flash just that they flash.) set the ebrake or chalk the wheels. mae sure the transmission is in nuetral. then jump the starter with a 12v source and see if it starts. if this doesnt help I will give you something else to try.

if you do not get any lights on the ecu. if the fuel pump does not prime and shut off after 3-5 seconds or the relays continue to click repeatedly without you touching anything. turn it off!and disconect the battery imidiatly you have a wiring issue and if you dont fix that issue you risk damaging the ecu

[oXeNo]

Thanks for the reply, but ok. It almost seems like there is a short somewhere or something; the ecu cuts on properly and only one relay clicks I can grab the relay and feel the click only in one hand. When I cut the key on, the relay will rapidly click constantly. The fuel pump will not prime while the relay is clicking like that. But I can turn the car over a few times and the clicking will stop sometimes and then the fuel pump will prime but then still no spark. It makes me almost think it could be the CAs but I am not sure.

[budderigs]

you have the 4 post green relays right? try switching the two relays around? same result?

[oXeNo]

Yes I do. And I have tried that as well, very same

[budderigs]

you are going to have to pull that harness out and check it. if you keep playing with it you are bound to mess up something. I will go through my notes quick. you only need 3 wires connected to make it run. I will be right back with those. disconnect everything else and I will try to walk you through it.

[oXeNo]

Alright will do

[budderigs]

do you have some lenths of wire to make jumpers?

[budderigs]

alright I got all my notes together what I want you to do is negate as much of the car as you can. disconect the engine harnes from the car wiring. leaving only the black with pink stripe connected to your fuel pump relay. as long as you didnt cut a bunch of the engine harness up there should be no issue singling out yor problem.

let me know when you get to that point or if you made any changes to the engine harness.

[oXeNo]

Ok well I just went a head and pulled the harness out, one thing I did notice was, the fuel pump will not prime unless the plug that goes to the aac is plugged in. If it isn't plugged in it's pretty much dead. I didn't do this wiring I got this swap as a set cause it came out of a running s13 like mine. Everything looks correct though. There was a sr20 in my car previously.

[budderigs]

that will work out just fine we are going to wor around that. is the harness you have supposed to be plug and ply then?

[oXeNo]

Alright, and yeah it was suppose to be. The only part I had to change was the dash plug, and I know I did that right it's just color matching with that.

[budderigs]

For right now we are going to leave that disconnected if there is tape or loom going around the plugs pull that off. Down to the main harness. Sense im not positive on which plugs are fir what on your harness do this on all of them I think there is 5 total but you only need the wires from three.

[oXeNo]

Alright I will. That wasn't to much tape on them, I'll go ahead and take that off.

[oXeNo]

Alright I'm done with that.

[budderigs]

please read all of this before doing anything.
ok to make it run you need 5 wires.

black pink strip connects to the black with pink strip for your fuel pump relay in car. the rb20 harness does not have a fuel pum relay.

find the thick black red stripe.
" " thick white purple strip
" " not so thick white black stripe.
these three wires find a way to jumper them to a 12v power. preferibly direct fused battery power 15 amp. these three wires are what im going by as the most importent part of this test it is importent that you do not reconnect these to your harness jumper them to the battery and if possible use a fuse at 15amps.

ground the engine to the car if it is not directly grounded to the battery. use a battery jumper cable if need be.

then find the thick black with white stripe wire and either jumper it to make momentary contact with the battery or reconnect it to your key switch start.

begin with positive battery cable disconncted ground the engine first. connect the fuelpump wire second,conect the positive battery cable third, then connect the three wires previously mentioned to your battery + once you do the fuel pump should turn on for three seconds. after the fuel pump stops try cranking the engine by applying 12v power to black whte stripe to start the engine and report back with your fndings.

[budderigs]

im going to go to bed relitivly soon. if you get it to start following the guild I left for you then your engine harness is wired correctly and there is a problem with how it is wired to the car.


I looked this over and it looks like it should help you quite a bit. I verified it with my car as well as my notes that I made when I did my swap and it is spot on.

RB20DET Wiring Guide For Dummies (http://www.nicoclub.com/archives/rb20det-wiring-guide-for-dummies.html)

[oXeNo]

Ok thank you very much for the help. I went to sleep as well but I am starting on it now

[ultimateirving]

Just wanna say, Props to Budderigs, Very nice guy to help diagnose wiring issues over the net. And he keeps checkin back to help!

I read all the posts and he seems very knowedgeable, best of luck oxeno!

[oXeNo]

Yeahh, I agree with you man. He was very helpful, I give him mad thanks. But I figured out what it was last night. Turns out I had a blown trace on my ECU board. I repaired it with some circuit writer and it started right up. I am finishing bolting everything up today and getting it running better. Leaving Facebook... | Facebook (http://www.facebook.com/l.php?u=http%3A%2F%2Fyoutu.be%2FioJ5Qk7Qzwg&h=sAQHUg1K_)
^thats a video of it running now.

[budderigs]

thanks for the shout out glad to here you got it running.