CaptainObviousI

Hi I am new to this site and I've been having issues with my Z. It was running recently but then it suddenly starting chugging and surging like it wasn't getting fuel. Was driving and then it just quit. It cranks and cranks but doesn't fire. Replaced fuel filter and the fuel pressure regulator but no go. Fuel is getting to the injectors so there's no clogs. Cleaned all the injectors and thought it might be fuel pressure. Hooked up a gauge, turn the key, pump comes on and the pressure goes up to 40psi and then slowly drops off. Checked the injector plugs and there was no power to the plugs while cranking so we're thinking that the injectors are not getting power. Any help would be awesome thanks.

Injuneer

There should be 12V to the pink wire at each injector harness plug at all times when the key is on. The PCM supplies a pulsed ground to fire the injector. If you don't have 12V at the injectors, a fuse is blown. There are two fuses, each supplying four injectors.

Scan it for codes. DTC 16 for the low resolution pulse signal from the optical cam position sensor in the Opti. Code shuts down the fuel system after two crank rev's if the PCM can't find the signal. Code does not turn on the SES light.

You need an OBD-1 scanner, and an adapter plug to connect the scanner's 12-pin connector to your 16-pin ALDL connector. Or use jumpers on the pins as shown on shbox.com

GaryDoug

If you get the Actron CP9185, it will work for your 95 without any extra adapter cable. I just received one and verified operation for a 16-pin connector with the OBD1 pcm. Prices vary dramatically from over $300 to this one: http://www.ebay.com/itm/Brand-New-Elite-AutoScanner-Actron-CP9185-Code-Scanner-Kit-for-OBD-ll-with-CAN-/381226701395?_trksid=p2054897.l4275

CaptainObviousI

Thanks for the replies! I was also wondering is the fuel pressure supposed to stay at 40psi when the pump turns on or is it normal for the pressure to slowly drop?

Injuneer

Should go over 40psi with the engine off, pump running. When the pump shuts off after the two second prime, pressure should drop slowly, if at all. But a fast drop can be due to a bad check valve in the pump. That can cause extended cranking, but once the engine starts, it has no effect.

Did you check for 12V at the pink wire in each injector plug? If no voltage, did you check the fuses?

CaptainObviousI

All the fuses are good. I replaced the ICM but I don't think that was the issue.

Injuneer

OK.... did you check for 12V on the pink wire at each injector? Your first post indicates you have no power to the injectors while cranking. Which one is it?

Do you plan to scan it for codes?

CaptainObviousI

So I checked all the injector plugs and they all have power within the factory specs about 11.7. I checked for spark and turns out there isn't any. Checked the ignition coil plugs and there's power there as well so I'm guessing that it has a bad coil.

Injuneer

When cranking the engine did you verify AC volts on the white wire from the PCM to the ICM? See Shoebox's procedure, or the "sticky" at the top of the LT1 forum?

Did you scan it for codes?

CaptainObviousI

No I didn't. I just turned the car on to get power and checked to make sure there was power going to the ignition coil. I tried hooking up a scanner but it wouldn't connect. 95s are OBDI but I think mine is a late model 95 since it has an OBDII plug.

GaryDoug

All 95 F-bodies are OBD1 and have the 16-pin connector. That's why I suggested one of the very few handheld scanners that work on the 94 and 95 cars. That's also why I said you would not need the OBD1 kit for that scanner. The Actron CP9185 can be found at Advance Auto parts for $175, on ebay for less. http://www.ebay.com/itm/Brand-New-Elite-AutoScanner-Actron-CP9185-Code-Scanner-Kit-for-OBD-ll-with-CAN/131499606390?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D30004%26meid%3D4b90e5ecc09242c6be2f266f69cd3a5f%26pid%3D100011%26rk%3D2%26rkt%3D4%26sd%3D381226701395
Or, if you have a portable pc and buy a $55 cable, you can use my scan app, Scan9495. See it in the stickies.

CaptainObviousI

Ok because I was checking around and I guess the 95s have the OBDII style connector but are still OBDI which is why the reader I have didn't work

Injuneer

You've had this info for 2 weeks. You really need to pay attention to what people post when they are trying to help you.

CaptainObviousI

So it turns out that the wiring harness that plugs into the optispark had come unplugged somehow. No idea how it happened. I was reading up and someone mentioned to check it for corrosion and there it was unplugged. Plugged it back in tried starting it and it popped right out again. Ordered a new harness since the tab on the old one is broken off but it fires right up now. Still has a running issue once its warm but I'm gonna look into it. Thanks for all the responses

Miner3

I am having trouble with no injector pulse. Have the cheap code reader that doesn't work just turns on fans. But I have the tunercat program and can get into the eprom. Could I view my trouble codes somewhere in one if the tables. Get spark, 12v to injectors, we put in new opti. But not sure if buddy timed it correctly. I'm thinking a trouble code is killing it. The reason we changed the opti is the low res signal wasn't there when harness was hooked up. If the computer decides to kill engine at startup would that low res show no pulse? High res signal is there we used a led to check pulses.