VATS Problem
Thread Starter
4th Gear
Joined: Jun 2011
Posts: 4
Likes: 0
VATS Problem
Electrical Issue. I have seen many posts on the problems with the VATS. I recently installed an aftermarket stereo in my 1991 corvette. The stereo worked fine but the car would not turn over after I installed the stereo. I purchases a bypass from Mid American and installed it today. It cranks but does not start. I am thinking the VATS is still not allowing fuel to flow to the engine but I am hoping someone has had this issue after installing a bypass and can help me. Does anyone have an ideal that I could try? Sure appreciate any suggestions or help.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
VATS bypass ( that plugs in under steering column ) does work on '90+ models with the CCM.
Needs VATS deleted from the tune.
Check for fuel supply pressure at fuel rail and injector pulse.
Have you got spark ?
Faulty dist will result in no signal from dist to computer to tell it to pulse (spray) the injectors
Needs VATS deleted from the tune.
Check for fuel supply pressure at fuel rail and injector pulse.
Have you got spark ?
Faulty dist will result in no signal from dist to computer to tell it to pulse (spray) the injectors
Thread Starter
4th Gear
Joined: Jun 2011
Posts: 4
Likes: 0
How do you delete the VATS from the tune? I really appreciate your help. I have work on it all day. It cranks but still no fuel. Both fuel relays show no power. I bypass the relays and the fuel pump starts but still does not start. I have had some friends look at it but we are all frustrated now. Thanks Rodj.
Melting Slicks
Joined: Aug 1999
Posts: 2,240
Likes: 41
From: Baltimore, MD USA
Check to see if any ECM or CCM codes are set.
With a piece of wire, short Pin A to Pin G on the
diagnostic connector above the drivers right knee.
Turn the ignition on.
Look at the digital display in the dash cluster
and post what numbers you see for
Module 1 and Module 4.
[FlElDlClBlA]
[GlHlJlKlLlM]
Also what do you mean by both fuel relays. The
L98 engine only used one relay. The LT5 used
both fuel pump relays.
With a piece of wire, short Pin A to Pin G on the
diagnostic connector above the drivers right knee.
Turn the ignition on.
Look at the digital display in the dash cluster
and post what numbers you see for
Module 1 and Module 4.
[FlElDlClBlA]
[GlHlJlKlLlM]
Also what do you mean by both fuel relays. The
L98 engine only used one relay. The LT5 used
both fuel pump relays.
Last edited by Hooked on Vettes; Jun 25, 2011 at 11:13 PM.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You got good info from rodj!
Use a timing light to see if you have spark during cranking.
Use a noid light (available at parts stores) to see if the injectors are being pulsed during cranking.
Use a fuel pressure gauge on the shraeder valve at the end of the right side fuel rail, you should have 35-42 psi.
Spray starting fluid into intake and see if the engine will start. If so, you have a fuel problem.
When you have a problem with your car you don't start replacing parts nilly ***** and you don't start guessing at what the problem is, you get your tools out and you diagnose what is missing that prevents the engine from starting and continuing to run. Engines need spark, fuel, air, and compression in order to start and continue to run.
Use a timing light to see if you have spark during cranking.
Use a noid light (available at parts stores) to see if the injectors are being pulsed during cranking.
Use a fuel pressure gauge on the shraeder valve at the end of the right side fuel rail, you should have 35-42 psi.
Spray starting fluid into intake and see if the engine will start. If so, you have a fuel problem.
When you have a problem with your car you don't start replacing parts nilly ***** and you don't start guessing at what the problem is, you get your tools out and you diagnose what is missing that prevents the engine from starting and continuing to run. Engines need spark, fuel, air, and compression in order to start and continue to run.
Heel & Toe
Joined: Jun 2011
Posts: 16
Likes: 0
My problem turned out to be bad connection at the VAT module, the wire that gives the ecm 5 volt signal to fire the injectors not making connection, but but the starter relay circuit was, if I pushed on the electrical plug into the VAT module the injectors would fire and car would start. Wish I would have found before I spent $$$ on replacing sensors, modules, and ignition switch needlessly.
If while putting stereo in if you pulled on the wiring harness you could have lost a connection somewhere.
jfb is correct diagnose it, did you check for codes?? I got a VAT code and the engine light was not on.
If while putting stereo in if you pulled on the wiring harness you could have lost a connection somewhere.
jfb is correct diagnose it, did you check for codes?? I got a VAT code and the engine light was not on.
