Startup Help....
Thread Starter
Staging Lane
Joined: Jun 2003
Posts: 77
Likes: 0
Startup Help.... Well, last night i tried to start the Z...and to no avail. It did that "VATS" typical error and only ran for two seconds or so. But I have a VATS bypass box that i had made and included in the curcuit is a light that tells me when it is sending a signal to the PCM. When I started it, the light only went on for cranking. Is this correct? Or shoudl it send a constant signal in the Run position? I also was looking at the fuel system. I have the "returnless" system, but in the manual it does say that it has a "T" in the fuel line so i presume additional fuel pressure can be regulated by the Fuel pump? Should I "T" off the fuel line? What else should i check for in finding this problem? 
But those two seconds or so sounded awfully good!!!
Any help would be GREATLY appreciated!!!!!
But those two seconds or so sounded awfully good!!!
Any help would be GREATLY appreciated!!!!! 
TECH Apprentice
Joined: Oct 2002
Posts: 321
Likes: 0
From: Woodstock, IL.
Re: Startup Help.... The vats box should be sending a signal in both crank and run...... By returnless. Are you using a modern f-body pump and intank regulator? You need some kind of regulator in your set up or you will burn out the pump.
Thread Starter
Staging Lane
Joined: Jun 2003
Posts: 77
Likes: 0
Re: Startup Help.... The regulator is off of a 2000 Fbody. So it is internally regulated and last night i noticed that when i had "t"d theline off so that it could hook up to the return side of the pump, the car didnt run as long. When i took off the T and ran a straight line to the motor...it seemed to run for just over 5 seconds. As far as VATS goes, i did set it up to run on both on and start positions. hmmm... I checked for spark and i have that in all 8. I dont have any vacuum leaks. Tonight i will run a fuel pressure guage to see whats happening fuel wise. Any other recommendations?
TECH Apprentice
Joined: Oct 2002
Posts: 321
Likes: 0
From: Woodstock, IL.
Re: Startup Help.... I think I would hook a pressure gauge to the shrader valve on the fuel rail. You should have around 55 psi. Then I would try to start it and have someone else spray starting fluid or carburetor cleaner in the intake and see if you can keep it running( short burst not full spray). Don't run it too long on the either just long enough to know it is not spark related. If it will start on its own but not run, and you can keep it running on either than it is most likely vats. Other than that make sure all the pink wires have 12v in run and that all the grounds are hooked up. I guess you could also double check all your connections. Sometimes they can seem to be connected but not all the way.
Thread Starter
Staging Lane
Joined: Jun 2003
Posts: 77
Likes: 0
Re: Startup Help.... I am thinking it is VATS related. I tested the bypass box i was using and it seems to be sending a 25 Hz signal vs what it shoudl be sending, a 50Hz signal. So i got another one off of ebay and we'll see if that works. Hopefully!
Thread Starter
Staging Lane
Joined: Jun 2003
Posts: 77
Likes: 0
Re: Startup Help.... So i figured it all out... it was of course VATS. I reinstalled a working bypass box and it started right up. Now its time to go run the beast!!! I'll be putting up some pics as soon as i can get access to a digi camera. It sounds great!! 
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Thread Starter
Staging Lane
Joined: Jun 2003
Posts: 77
Likes: 0
Re: Startup Help.... The VATS Bypass box is a circuit that sends a 50Hz pulsed signal to the ECM. It tricks the ECM into thinking it is getting a signal from the stock key (which has a resistor). That stock signal would normally get sent to the BCM and then from there would get sent to the ECM. The bypass box basically allows you to run the motor without the original key, or the BCM. You just plug in the bypass box/circuit, and youre ready to run. You can make the circuit for about $10 worth of parts at RadioShack...or you canjust buy one off of Ebay for abotu $20 including shipping. Not a bad deal.
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