No spark, no fuel

Discuss the RB20, RB25 and RB26 series engines.
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lilskyline240
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No spark, no fuel

Postby lilskyline240 » Sat Apr 05, 2008 9:00 am

Well i found what was causing my engine control fuse to blow. Tried to start it again and realized now that my injectors dont fire, and im not gettin spark. this is on a rb25 s2 so it has an internal ignitor. i have fuel pressure at the rail and my fuel pump primes. all my relays work and all fuses are fine.

think my ecu is shot?


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lilskyline240
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Re: No spark, no fuel (lilskyline240)

Postby lilskyline240 » Sun Apr 06, 2008 5:10 am

anyone? Doesnt normally no fuel and spark mean ur ecu is shot

kjlindgr
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Re: No spark, no fuel (lilskyline240)

Postby kjlindgr » Sun Apr 06, 2008 5:57 am

The fuel pump is controlled by the ECU. Typically if an ECU is fried, it's an all or nothing sort of a deal meaning if it's shot, nothing will work.

Do you have power to the injectors when the car is on? Do you have power, ground, and a correct reference signal to the coils?

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lilskyline240
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Re: No spark, no fuel (kjlindgr)

Postby lilskyline240 » Sun Apr 06, 2008 6:21 am

hmm. Those are some things for me to check. im a wiring newb so im not good with testing all that crap. Do you know where i can get a writeup on how to do that?

also i thought that the fuel pump relay runs the fuel pump for like the first 30 seconds?

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Re: No spark, no fuel (lilskyline240)

Postby kjlindgr » Sun Apr 06, 2008 6:29 am

The fuel pump relay is controlled by the ECU. It's the ECU that tells it when to kick on and off.

Not sure on where to get a write-up but if you have a multimeter, you're golden. I believe from what I can remember from 4-5 years ago when I was doing something similar, the injector power wire is a white/black wire. Don't quote me on that but if you have a wiring diagram of any kind, you'll be able to tell what wire is which.

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lilskyline240
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Re: No spark, no fuel (kjlindgr)

Postby lilskyline240 » Sun Apr 06, 2008 6:35 am

so i just check to see if i have volts going to the injectors? and coils? is there a separate ground for the injectors or coils on the harness?

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Re: No spark, no fuel (lilskyline240)

Postby kjlindgr » Sun Apr 06, 2008 6:38 am

The injectors have two pins...a +12V power and a ground. The ground goes back to the ECU. The +12V power gets energized when the car is in the "ON" position. The ECU flicks ground signals to fire the injectors.

Coils are similar. The coils get a +12V power and a ground to power the coil. The igniter fires the reference signal to discharge the coils. This reference signal also goes back to the ECU.


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lilskyline240
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Re: No spark, no fuel (kjlindgr)

Postby lilskyline240 » Sun Apr 06, 2008 6:43 am

its an rb25 s2 so the ignitor is internal in the ecu. Ill go check for volts at the coils and injectors tomorrow. If there is a 12v power supply then the ecu isnt shot. its another problem then right?

how do u test ur CAS?

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Shocker
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Re: No spark, no fuel (lilskyline240)

Postby Shocker » Sun Apr 06, 2008 7:18 am

to test the cas, remove the coils from the plugs, disconnect the fuel pump fues, turn the cas by hand, if you got spark coming from the coils and can hear the injectors firing your CAS works and the wiring is correct.

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lilskyline240
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Re: No spark, no fuel (Shocker)

Postby lilskyline240 » Sun Apr 06, 2008 1:44 pm

well i found that i have 12v power at the injectors and at my coils so im guessing my ECU isnt shot? My next step would be to check my CAS im guessing. Since the ecu fires the injectors and coils by grounding them, could i have a bad ground at the ecu somewhere that im missing?

if im not gettin spark or fuel when i turn the CAS by hand does that mean that is my problem? or could it still be a bad ground

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Re: No spark, no fuel (lilskyline240)

Postby kjlindgr » Sun Apr 06, 2008 4:26 pm

Having power at the coils and injectors doesn't rule out having a fried ECU since power doesn't come from the ECU.

Do the CAS test and report the findings.

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Re: No spark, no fuel (kjlindgr)

Postby lilskyline240 » Sun Apr 06, 2008 10:23 pm

i hightly doubt its gunna pass the CAS test. cuz i took the coils off and put plugs in them to test for spark and have the fuel rail upside down laying on my manifold and when i crank the car no injector fire, and no spark. Is there a way that i can check the CAS other than that? like OHM or voltages as i turn it?

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Re: No spark, no fuel (lilskyline240)

Postby kjlindgr » Mon Apr 07, 2008 4:37 am

Just out of curiosity, can you post what ECU, engine harness, and engine you have? I know you said you have an RB25 S2 ECU and I'm sure you have another post somewhere telling what all you have but I'm lazy.


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lilskyline240
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Re: No spark, no fuel (kjlindgr)

Postby lilskyline240 » Mon Apr 07, 2008 5:42 am

everything is from an rb25 s2. Im tryin to get ahold of a r33 FSM but its not working. I want to OHM out the CAS to see if its good or not. Im going to madison to pick up a rb25 s2 ecu to borrow from a guy if i cant figure anything else out

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lilskyline240
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Re: No spark, no fuel (lilskyline240)

Postby lilskyline240 » Mon Apr 07, 2008 10:08 am

well i got ahold of a r33 FSM and only had a chance to check pins 2 and 3 per the FSM before work and im not sure what my results mean



on pin 2 i get a constand 12volts when its supposed to be 0-5pin 3 i get 0.1v

this is while turning the CAS

i might be checking it wrong? imput about this would help

also no spark or injector firing when i turn the CAS by hand with the key in the ON position

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Re: No spark, no fuel (lilskyline240)

Postby kjlindgr » Mon Apr 07, 2008 10:29 am

Pushing 12 volts into a sensor input that's only supposed to be seeing 0-5 volts is bad. It usually results in smoke.

Ninja Edit: Who did your wiring?

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Re: No spark, no fuel (kjlindgr)

Postby 240z4u » Mon Apr 07, 2008 11:11 am

Said the swap was in a running car before. If you do have 12v at the CAS that seems abnormal. I would assume its a 5v circuit like everything else is.

Evan


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lilskyline240
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Re: No spark, no fuel (240z4u)

Postby lilskyline240 » Mon Apr 07, 2008 7:32 pm

im not sure who did the wiring. its weird cuz i pulled the harness off a running Rb25 s2 in a s13 that was working fine. Now when i put it in my car something is all messed up. I dont get it. Im going to go check my volts again. Maybe i screwed it up somehow. Otherwise ima have to take my whole harness out and send it to Carl H

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lilskyline240
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Re: No spark, no fuel (lilskyline240)

Postby lilskyline240 » Tue Apr 08, 2008 4:58 am

well i had more time to test my voltages and they seem ok per the FSM for the CAS. when i first did it i mixed up which end was which on the plug. So pin 1 should be pin 4 and pin 2 supposed to be pin 3. heres my findings

Pin 1 ~ .1vPin 2 ~ 12vPin 3 ~ 0-5v while spinning by handPin 4 ~ 0-5v while spinning by hand

these pin Numbers are per my picture here. Not the FSM. the FSM has them in reverse order

I still get no spark or injector pulse while turning it by hand

v

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Sil240
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Postby Sil240 » Tue Apr 08, 2008 10:10 am

Hey I had the same problem.Try unplugging the ecu then plugging it back in and make sure it is in good.


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240z4u
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Re: (Sil240)

Postby 240z4u » Tue Apr 08, 2008 2:22 pm

Good luck man! Hope my spare ECU works.

Evan

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lilskyline240
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Re: (240z4u)

Postby lilskyline240 » Tue Apr 08, 2008 3:38 pm

well i went and visited 240z4u and we think we found my problem. Either the ecu i have is shot, or its not even from an RB. we tried it in his car and it didnt work at all. does anyone know what engine this comes from?


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240z4u
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Re: (lilskyline240)

Postby 240z4u » Tue Apr 08, 2008 5:20 pm

We opened my spare ECU and his ECU.

His ECU has the same motherboard number, and looks very close to mine as far as component layout. However, the main chip that looks like a processor has a different number on it.

CAS definitely works fine.

Evan

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Re: (240z4u)

Postby 240z4u » Tue Apr 08, 2008 5:39 pm

http://www.autotekelectronics....=4309

Says 2.5 liter skyline ECU on this site.

I think its just dead!

Evan

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lilskyline240
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Re: (240z4u)

Postby lilskyline240 » Tue Apr 08, 2008 10:26 pm

could be from a Series one also. but whatever it is, it doesnt work. So hopefully ur spare ecu works wonders tomorrow morning after i clean up my grounds

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lilskyline240
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Re: (lilskyline240)

Postby lilskyline240 » Wed Apr 09, 2008 6:56 am

IT RUNS!!! I took 240z4u's advice and ran better grounds from my battery in the trunk through my chassis and bolted it to the block. Then pluged the ecu i borrowed from him in and BAM! it started!!!

I AM NO LONGER A MEMBER OF THE NRRBA!!!

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Eikon
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Re: (lilskyline240)

Postby Eikon » Wed Apr 09, 2008 7:20 am

Congrats!

So it runs on his ECU? Does it run on your ECU? Or do you have to find a new ECU now?


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Re: (Eikon)

Postby 240z4u » Wed Apr 09, 2008 7:23 am

His ECU is bad, my car would not run with it installed either.

Congratulations man.

Evan


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lilskyline240
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Re: (Eikon)

Postby lilskyline240 » Wed Apr 09, 2008 7:24 am

runs on his ecu. But i got a guy who is selling me a good ecu for 140 right now

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Postby kjlindgr » Wed Apr 09, 2008 7:39 am

Glad to hear the issue was found!


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