RB20Det won't start

[ltnick4]

Hi everyone, i'm new to zilvia page and was hoping to get some help. My 240sx with rb20 isn't starting. The issue I am having is that the injectors aren't pulsing, both leads on the injectors are showing continuity to ground. I removed the cam angle sensor and spun it by hand, fuel pump primes and spark plugs have spark. I also have fuel up to the rail and can get the car started with starting fluid. Any tips are appreciated thanks in advance

[Nidd]

Check the fuel lines. I've seen multiple people accidentally put them back wards. When you spun it by hand could you hear the injectors tick or make any noise?

[ltnick4]

No noise from injectors and fuel lines are on the right way, car was running and driving perfectly I had actually drove it to a friends (turbo timer kept engine running for roughly 5 minutes) and I came back 5 hours later and wouldn't start

[ltnick4]

I also put a noid light on the injector plug while attempting to start and spining cas by hand to make sure and there was no pulse. Theres no activity at injectors, but there is spark and the pump runs with good pressue

[ltnick4]

Anyone have any other ideas? I'm ordering an ecu because I believe that might be it

[zwzweston]

If you're turning the CAS and the injectors aren't clicking, that is your problem. Either they aren't getting power, or they aren't getting signal from ecu.

[ltnick4]

Alright hopefully that's it, just wanted to see if there's any other tests I could do while I wait for ecu ill post back when ecu comes in

[zwzweston]

If you're pretty confident with wiring, you could tap one of the injector 12v wires and give it power directly, then see if it clicks when the CAS is turned.

[dorkidori_s13]

silly question, but did you check your fuel pump fuse? IIRC, RBs use low impedance injectors and require a resistor box... is the resistor box still good? also, did you try removing your turbo timer and then try starting the car?

not belittling you in anyway, just pointing out simple things that tend to get over looked.

[ltnick4]

The wiring is intact so I will have to try that, fuel pump fuse is intact and I did remove turbo timer and still no start. I did not know that they is a resistor box also so I will have to check that! Thanks guys

[bagezuhesre]

think so, just wanted to see if there's any other tests I could do while I wait for ecu ill post back when ecu comes inhttp://goo.gl/CNYTA7

[ltnick4]

Got the ecu in today, still no start, no injectors pulse, wiring seems to be intact, where is the resistor box located? what can stop only injectors from pulsing?

[zwzweston]

If the injectors are good, and the ecu is good, and the injectors are getting power, then the CAS is probably the issue.

[ltnick4]

Injectors don't have power but have continuity to ground on both leads, I spun the Cas by hand and I had spark I thought if you had spark the Cas was still good?

[zwzweston]

Okay. For the engine to start, you need spark, air, and fuel (which is the injectors pulsing). If when you rotate the CAS, you're getting spark, but no response from the injectors, the issue lies between the CAS and the injectors. AFAIK, the ground wire for the injectors is used as a signal by the ecu. All you need is signal and +12v, the grounding is controlled by the ecu which is how the injectors are controlled.

[ltnick4]

So what your saying in a sense is that the injectors kind of get power from the Cas so the Cas could be good for spark but not sending power to injectors?

[zwzweston]

No. The injectors are controlled by the ecu. They have constant +12v, and are turned on and off by a ground signal from the ecu. The CAS records the position of the cam and sends that information to the ecu, which dictates how it controls the spark and injectors. If you're rotating the CAS and getting spark from each plug, the CAS should be fine.

[Yellow4g63]

Did you check the Relays near the ecu? one should be for the injectors and the other for ignition. dorkidori_s13 only the RB26 uses low impedance injectors, The RB20-25 uses high's.

[ltnick4]

I swapped the relays with some blue and green spares and still no power at injectors, where does the power come from on rb20 injectors? The ecu directly or another source?

[zwzweston]

The injectors get switched ignition power. Follow the path in this diagram: it goes from injectors to the ignition relay itself.

[ltnick4]

I thought the feed from the ecu was a ground?

[zwzweston]

Yes, it is. The injectors are supposed to receive constant +12v as soon as the ignition is turned on. The signal from the ecu is a non-constant ground that is varied to control the injectors.

[ltnick4]

Should I have power with the key foward on the two relays by the ecu and or the egi relay?

[ltnick4]

If ecu id disconected would I still read a constant ground with key off?

[ltnick4]

I got the car running, it was bad electrical in several spots particularly above the wheels, thank you for your help everyone!

[zwzweston]

Cool! Glad to hear you got it sorted out