Hey all. I'm finally ready to start my car and it appears I'm getting now fuel. With starting fluid it'll attempt but no start. Double checked grounds and all look good. I think it's just no pulse or clogged injectors? Not sure how to check either but would love some insight. As tomorrow is my last warm day for a while.

Yes vats should be removed

 

Check fuel pressure and check for spark

 

I have spark because it startson starting fluid. I'll be at the parts store after work to grab a noid light for inj. Pulse. Maybe they will have a gauge to check for pressure. I would imagine I'm good. I'm using a walbro 255 and the vetted regulator. I'm really hoping the injectors are just gunked up from sitting around for a while

 

AutoZone rents them out for 150 , kind of expensive but you'll get your money back , if you have spark and fuel pressure then I'd say you are probably right about the injectors

 

Ok, I'll rent that out too.just so I can rule it out.

 

Ok here are the results.. right at 52ish psi for fuel pressure. Also noid light confirmed that the injectors are not pulsing. Any suggestions on the next step?

 

Check for 12v IGN on the injector connectors. Hopefully its just a blown fuse

If you have 12v and there is no pulse then its VATS

 

and if it is neither of those then send them to southbay to get tested.

 

I used a test light as I do not have aNY other way. I have power with key on but I'll check and see if I have power while in crank position.

 

Well I finally hooked up with my tuner and completely reset the ecm. Also swapped it from truck platform to firebird just because. Confirmed again vats is off. Still no injector pulse. Car starts if I use starting fluid. Fuses are all good. No idea where I should go next. Besides going crazy.

 

What wire did you check for inj pulse?

Tracking down wiring gremlins is frustrating but it'll be worth it. Plus I learned a crap ton about wiring while doing it, which is nice.

 

Well harness is brand new from pocket, but one wire has 12v othe is grnd. Noid light confirms that there is no pulse but that's where I'm at. Plus all the fuses are good and new

 

So iv had several people say it's the crank position sensor. Does anyone else know of a way that you could test it? Also would it still have spark if it was bad?

 

Check the pins on the Crank Sensor, for reasons beyond me the first PCM I tried would NOT supply the sensor with a ground (low ref) signal.

I grounded the sensor the body, and it started right up.

 

Interesting. I will hopefully get a scanner on it this weekend to see if a. The sensors are good and b. If there's any codes. When it does start with the fluid I get a solid tach reading. If there was something wrong with the sensor or wiring would the tach even work?

 

Pcm uses crank and cam sensor so pcm can pulse injectors at right time , if all your wiring checks out then to included pcm , ign is always hot but pcm sends the ground signal to complete the pulse that's my understanding

When using noid when you key on should see 2sec prime or light on for 2 sec then when cranking light will pulse turn on and off

No way to chk sensors may or may not throw a code also double check your ground to PCM and engine and ensure its a good ground

 

That's where I'm at now, checkling all grounds. There wasn't very many on the harness to begin with but who knows maybe I missed one.

All I have that I can find is 1 on drivers side head, 2 on passenger side head. And 2 for my fans. All grounds seem to be good using my test light. Now is there a seperate ground for the ecm alone? Where would it be?

 

Have to look at diagram but there is no dedicated PCM ground

Did you ground battery to block and block to body ? I could be wrong tho but that's how I did it

 

Yes battery is grounded to head and with the grounds on the back I have a strap to the body. Everything seems good. Like I said other than the fact that I have no pulse. It's perfect. If that makes sense

 

After some reading some people said something about the starter enable wire needs grounded? Any idea on this or where this is?

 

If the tach works, then the crank sensor is good. Cam sensor is only used on start. If the cam sensor is faulty, it will take longer to fire, but will still crank and run. Im thinking your issue lies with fuel, either electrical or mechanical

 

Fuel pressure checked out to be good. I think it was mid 50s psi? I definitely am not getting a pulse from injectors. Not sure what else to check. As far as tach reading all I have been getting lately is a slight "bounce" of the needle reading maybe 1 to 200 rpm? Not sure what else to check for electrical.

Could one bad or clogged injector make the rest not pulse? I'll have to get another noid light and check all 8 injectors to make sure. Last time I had only checked 2 or 3 of them with the others still plugged in

 

If the tach moves at all, crank is sending signal

The engine will still start and run on 4 cyls, so a bad injector or two wont do it

Do you have a meter?

 

Atm just a test light, I can go grab a meter though. Suggestions on what I need to check?

 

I'm not sure when/how you checked your FP, but the first thought would be to make sure you're getting 12v on the fuel relay (should be green/white) when car is in the ign position.

You should hear the pump prime and get 12v on that relay. It'll only be 12v for like 3-4 seconds so either put the multimeter where you can see it, or get a friend to help.

 

Pressure was checked using the kit at azone. I'll check once I grab a meter but I know I'm getting power to them. My problem is the ground. I confirmed with a noid light. If that makes a difference

 

tap the body of the injectors while cranking. If they are gummed up this can free them. Ive had this happen on a couple that sat too long without running

 

Ok, I'll try that as well.

 

Ok, had a guy from GM come over with his tech 2 scanner and worked some things out for me. He can manually pulse the injectors and all 8 make a pronounced buzz/hum. If connected to a noid light they stay on rather than flash. Even with a cycle of all 8 injectors it still does not fire but it fires on spray. So we will be getting a different fuel pressure gauge to make sure that is right but any other suggestions? I am hopeing pocket can supply me with a schematic of his harness he made for me. Can someone point me to where i can find a schematic for mine? 87 gta 305 tpi.
Thanks guys this has been a long aggravating process but i think im getting somewhere.

 

So a little update, it's been terribly cold up here but I did manage to get my body wiring diagram and since my harness is a simulated fbody harness I just grabbed a diagram for a ls1 fbody. Mine is from a 2000. Have yet to get any further due to the temperature. Turns out my lights wouldn't even turn on! Way to cold for me. Anyways was hoping to get suggestions on where to start. Iv never had to do this before so I'm lost to be honest

 

1) If the Noid light stays on with the key on or when cranking, chances are wiring on the ground side of the circuit is either shorted out (shorted to ground) or the driver inside the computer is bad and the computer may need to be replaced.

2) If the Noid light does not blink at all when cranking the engine over, check for fuel injector pulse at multiple cylinders as you may just have an issue with that specific circuit.

3) If there is no pulse on all cylinders, check to see if the fuel injector is getting power with the key on and cranking. If still no injector pulse, then the computer is not pulsing the injectors open for some reason and more testing will be needed.

4) Again, you want the Noid light to blink consistently when cranking the engine over. This is a good signal.

You can also but 12 v power to injector I believe it should be a audible click vs a buzz or hum that's been my experience with that

You can also remove injectors to see if fuel comes out when 12v apply also and clean them your self

Now if you done all this you should check out side the box ie ensure fuel filter is connected correctly to include fuel pump , if you wore fuel pump backwards you will still here prime but it won't start I did that before lol check the pins to pcm ensure its making full contact happen to me also lol check fuses etc

 

Lights is different harness ensure ground and harness at good in engine bay but is seperate from engine harness

 

1.I have power to inj with key and crank. No noid light won't work.

2. When I checked I had good fuel pressure so that should be good.

3. Car starts on fluid.

4. With the tech 2 on the car and the injectors are cycled they all buzz/hum. But the noid light appears to stay on rather than flash.

Also this motor started before I bought it. I was there in person. Could the inj. Circuit go bad in between? Is there a way to test this other than finding some1 with a truck to test it on?

 

It appears that the injectors are just not grounding out. Without help with the tech 2 scanner

 

Voltmeter start testing circuits etc

 

Yea, I was afraid of that haha. Being iv never done this, what's the best way to check. Thanks in advance. Wiring just isn't my strong suit

 

So after my swap, I am having the exact same problem. The computer is telling me its a VATS issue, but the VATS system is working correctly. I have both a VATS box in my car that is wired to my key, and a bypassed bcm in my car. I have used both to try to start the car. It cranks fine, but I get P1626 as the trouble code. I have double checked the pinouts, made sure nothing is backing out from the connectors, and as with yours, it comes top life with starting fluid. Also I have no spark- PCM is not turning on the coils. I think I may have a bad PCM.

 

Interesting , unfortunately I haven't gotten a chance to touch mine. It's been pretty cold lately and I'm busy. I still think my problem is wiring but I can't seem to get my hands on a spare computer to rule it out either. I think I'd start there though.

 

I am getting the vats tuned out ... Something I am not crazy about. I like vats... But I guess the computer doesn't.

 

Hopefully that fixes your problem. Mine has been checked 3 times that it is turned off. Not sure where to start as far as wiring Kinda in over my head now haha

 

I just had a frightening thought. What if even though vats is off, the computer is malfunctioning. That could be your problem.

 

I would like to try and find another computer jic. But it ran when it was pulled. It had less than a month of down time. And has a new harness and tune. Also theres no codes and the Gm tech was stumped. I could only hope it is a bad ecm

 

Hate to say it but it sounds like a bad PCM

If you've got 12v on all the injectors, and the issue is definitely injector related, it leaves the ground leg. A goof on my part may happen on one wire leaving a dead cyl, but not all 8

 

I just plugged in the new ecm and I still got nothing from it. Not sure what to do at this point since the new ecm isn't working either. Sure Vats wasn't tuned out on this one but it should of still tried to start. Right? If I use the tech 2 it still turns on the injectors. So idk what that means. Could the crank sensor still be acting up even though I have spark? Oil pressure still reads so that's good. I'll have to go out and try starting fluid with the new ecm and see what happens. I still need to grab a meter and go through the harness but I'm not sure where to even start on that.

 

Even with VATS enabled, it should start for a second or two then immediately die. Yeah, Id say something is wrong

Just a hunch, but...
Unplug your TPS and look at the wire locations. Connector in your hand, looking at the wires going into the connector
Top left GRY
Top right BLK
Bottom Dk Blue

I goofed once and had the top two switched so the TPS read in reverse. 0% throttle read as 100% throttle which under start-up means fuel cut

 

Well, I unplugged it and turned it over and guess what it fires up! God Pocket i love you so freaking much. This thing had me at my wits end. That is backwards right? so all i need to do is remove pins from connector and swap?
Again holy crap it starts!! Now my hardest decision will be stick with my manifolds or get Racing innovations headers.

 

That's great news. Unfortunately for me I didn't have spark at the coil so it has to be the PCM. Besides I never in pinned the tps connector. Once again- that's great news!

 

Dang hopefully your new ecm will be in soon enough and that'll solve all of your problems

 

I apologize for that. It was my error that caused this headache

Yes, the pins are simple to swap. Pull the gray cap off to expose the terminals. Lift up on the black tangs and the terminal will pull out the back. A small pointy tool will help

 

No worries Pocket. You figured it out! We are all humans and I would buy another harness from you. Not to mention I think iv told several others to not waste their money on anything else and come to you.
Again thank you to everyone, I had a huge smile when that thing finally started.