CAS and injectors

Post by **HotWIRED** » Sat Jun 28, 2003 9:54 am

Does the CAS control the opening and closing of the injectors? I'm not getting any fuel and the plugs are not getting wet. I checked them all and no fuel. Does that mean I have a bad CAS? Where is the power wire for the injectors?? It ran few days back and now it doesn't. I have fuel pressure and a strong spark.

Post by **93semax** » Sat Jun 28, 2003 9:54 am

The CAS puts an input for ignition and fuel. IF the Cas was bad neither should work (in theory). The power wire for the injectors is gray I believe. An easy way to check if the injectors are getting a signal is to pull the #1 injector harness off and connect it to a spare side feed injector.

Post by **JonPowell** » Sat Jun 28, 2003 9:54 am

I would also try pulling a spark plug and seeing if you get spark. Check for fuel pressure also, are your fuel lines hooked up correctly? the feed goes to the rear of the fuel rail and the return is up front near the regulator. Try turning the CAS by hand and listening, if the injectors are working you will hear them fire. You can also put the ECU into diagnostics mode(not sure how, depends on your year and model). It will tell you if the CAS is ok or not. Check megalla's website for help on diagnostics.

Post by **HotWIRED** » Sat Jun 28, 2003 9:54 am

I don't hear the injectors opening when turning the CAS by hand. I do hear the fuel pump turn on and off, and fuel running through the fuel rail though. The ECU checks out good, no CELs. Both of my fuel line conections are up front. From the tank on the BOTTOM and return line on the TOP. Whats the power wire for the injectors? Is it the red wire (pin 4) on the RB body harness?

Post by **JonPowell** » Sat Jun 28, 2003 9:54 am

Check to see if your plugs are firing before you try replacing the CAS. I am not sure which wire is the hot for the injectors, but I will check it out for you and try to get back as soon as possible.

Post by **Vrtgrumpy** » Sat Jun 28, 2003 9:54 am

The CAS does control the injectors. It sends the signal to the computer to fire them. The Gray wire to all the injectors is always hot (12v). Pul the cas off the motor and turn it by hand the plus and injectors should fire(use a NOD light in #1 injector to see of its working.. You can get a NOD light at PEP Boys or any good auto parts store..

Post by **93semax** » Sat Jun 28, 2003 9:54 am

Like I said it should be a gray wire. All injector plugs have a gray wire going to them along with a different color wire for each. Disconnect the #1 injector plug since it's easy to reach. remove some of the insulation from the back of the plug. 1 wire should be gray and the other should be white. With the ignition in the on position check the voltage of the pin connected to the GRAY wire and ground. You should get normal battery voltage.

Also the gray wire does not go to the ECU. It branches off the injector harness and goes to the A-17 (?) plug.

Post by **HotWIRED** » Sat Jun 28, 2003 9:54 am

I know the gray wire is the power wire for the injectors. What I'm asking is where do they get their power source from. I'm not getting any voltage. I removed the fuel pump fuse so I could hear the injectors click with out the pump running. No clicking and no power. Where is A17 plug? I thought the injectors get their power from the ignition wire which the ignition relays get their power from right? I tried changing the relays with known working relays and the same thing. Did I wire something wrong? Should I try to wire them directly and see if that works? Should I rip my harness apart and start over?:help

Post by **RubHamuSan** » Sat Jun 28, 2003 9:54 am

grumpy is correct. the ecu sends a signal telling it to release power to the coil to fire. most likely you are not getting this signal.if i remember part of the wiring includes running a wire from the ecu to the coil pack or chip not sure. but i bet grumpy will give you some help.he does these swaps daily.

Post by **93semax** » Sat Jun 28, 2003 9:54 am

I *think* this is it (thank you opensource) http://azparttrader.com/rbhelp/IMG_2518.JPG

The injectors get their power from a fused 30a ignition wire when it's in a skyline. IT comes straight off the battery and is powered when the ignition is in the on position.

You made a post about 2 months ago with the same problem. You said the injectors were opening??I think you have a wiring problem.

Anyway what I would do is find a known good ignition wire and connect that gray wire to it.

Post by **HotWIRED** » Sat Jun 28, 2003 9:54 am

Yea, I did say that the motor started up. But it nevered idled more than a sec or two and it would die when you try to throttle it. What I thought was the injectors opening was actually the fuel running through the rail. Thats why I pulled the fuel pump fuse. I'm using the KA harness(s) with the RBs. If that helps any.

Post by **HotWIRED** » Sat Jun 28, 2003 9:54 am

Thanks for the pic 93semax. It took me awhile to remember about the Rb engine harness plug (up by the boost valve) that ran around the whole front end when I took it out. I now have power to the injectors. Thanks to all that has helped.

Post by **FAST-DATSUN** » Sat Jun 28, 2003 9:54 am

The power for the injector(12v.) is key on power and constant. The CAS send a signal to the computer and the computer Switches the ground to make the injector work. If you do not have 12v back track the harness to see why. Depending on who did the harness they tapped the Gray wire into some thing switched by the ignition switch...

Post by **93semax** » Sat Jun 28, 2003 9:54 am

Did you try to start it?

Post by **HotWIRED** » Sat Jun 28, 2003 9:54 am

Starts right up.

CAS and injectors

CAS and injectors

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