boerge

And how do I get to it?
Or, I need a place where I can find the "fuel enable wire" from the VATS system on a LT1 1994 Corvette.
I have looked for it at the red connector pin 25 and 30 on the ECM, but I have no wires at all going to pin 25 and 30. Is there another place on the ECM I can find this fuel enable circuit?

I have no books available.

Regards

Boerge

lefoy84

I would try to help you, but I have no idea what you are asking! If you have no books, how do you know about red connectors and pins 25 and 30?

JackVM

I have the service manuals, I'll look since I'll need to find these myself in the next couple of days. I have a VATS elimination module coming.

JackVM

Well my service manuals are for the 92 and I can't find anything called a BCM listed. The fuel delivery used in the VATS is called FEDS and is a serial link between the CCM and ECM. I don't know if this helps or not.

VenkmanP

There is no BCM. Technically there's no VATS - VATS became Pass-Key in 89.

The only "fuel enable" I can find in the FSM is the Fuel Enable Data Stream which is not a wire it's messages on the serial link between the PCM and the CCM.

The CCM is behind the radio. The serial data stream is accessible on the DLC.

Now - what the heck are you going to do with it. Are you planning to intercept and decrypt the password handshake?

Hey, you're getting us to help you steal a car, aren't you...

{edit - typo}

VenkmanP

As people in both your other threads told you, your problem doesn't appear to be VATS.

http://forums.corvetteforum.com/show...=no+fuel+start

http://forums.corvetteforum.com/show...post1557693116

boerge

If only the damned thing would start I would be happy if someone stole it...
Yes, people say it is not VATS, but presume the starter relay has been jumped, then it still might be I guess..I ordered one of these bypass modules, and cant find out where to hook up the signal wire.
It says pin 25 or 30 on red connector,ECM, but I have no wires going to those pins...Hence I am looking for the BCM/CCM due to the instructions that came with bypass module says there is a fuel enable wire going into it.
I find it hard to believe myself that this might start the car, but the module is here so I will hook it up for peace of mind.

I dont get any fuel into the cylinders, or only for 0,2 seconds, and then car dies.
I am also thinking of buying an extra ECM to try out.
If anyone else has suggestion they are welcome.

Also, what type of fitting will fit on the shraeder valve, I'm building myself a fuel pressure gauge.

Thanks for all help

Regards from Norway

JackVM

Perhaps the 94 is differnent then the 92, but the VATS according to my book can allow the car to crank over, but not deliver fuel. I'm having the same problem. I can drive the car for an hour or so and then the security and SYS signal pop up. I know if I turn the car off when this is flashing I know it won't start. I then have to let it set for a while, or disconnect the battery and wait a few minutes, and it will start again. It may start several times a day, then throw a fit. I've only had the car for a few weeks so I don't know the history of it. I did have a new radio put in it along with a wireless unlock feature. I'm not this had anything to do with my intermitted problems or not. I'm going to check behind the radio today and be sure the installer has not damaged or tied into the CCM some how. It's possible i have a bad CCM or ECM which will be another big ching ching at the dealership.

lefoy84

If Vats or PassKey doesn't like the key you inserted, nothing happens when you turn the key except a lot of bad words! Been there, done that!

boerge

I am installing the Vats bypass module, bakerelectronix.com, but so far I have not been able to locate any fuel enable wire, that the instructions with the module say are everywhere basically..
Any help on this please? Or maybe I need to look behind the radio?

Regards

Boerge

VenkmanP

You've got the instructions, we don't, so we don't know how it installs. From what they've got on their website it sounds like it talks to the CCM on the serial data link.

Would be a lot simpler to get tunercats and just turn off VATS.

What's the back-story on this problem? Did you just buy the car and it was like this?

boerge

My friend bought the car like this, it had been sitting for a few months, when he got the car, after transport, it refused to start.At some point, we don't know last, it has been running obviously..
My friend went to work in the US, I offered to try to get the thing started.
Turned out to be harder than I expected.
Now if the instructions that came with the box was telling the same things as the car specs, then it would be nice, but as said, no wire going into pin 25 or 30 on red connector, so I cannot hook up there I assume, then I am looking for next place which is pin 10 on the BCM connector, which I can't find.

I'm sick of the whole car to be honest.
It purrs nice for 0,3 secs first time I start it, and then dies. Further cranking whatever, completely dead. Then leave car for some time, ignition again for 0, 3 secs, and then dies.

I am thinking to buy a spare ECU to try. Must have something to do with the fuel going out of the injectors I believe, since I have confirmed spark.

Thanks for all help

Boerge

IRAraid

If the car cranks, it's not the VATS or Pass Key. They prevent cranking (the solenoid never gets a signal).
Since the car starts then runs for 2 or 3 seconds, it's likely the oil pressure sensor and relay. They cut out after 2 or 3 seconds when there's no oil pressure. Actually they are bypassed for 2 or 3 seconds so the oil pressure can build.
Could be the pressure sensor (at the back of the intake, just in front of the firewall) or the relay. There are two sensors there, the other feeds the analog oil pressure gauge in the dash.
I don't know the relay logic for the oil pressure sensor circuit in a '94. It may be fused. My bet would be that the wire is off the sensor or the sensor is bad. The second 'easy' place to look is for an oil pressure sensor fuse. Also, is there plenty of oil in the crankcase?
Perhaps someone with a '94 can chime in on the location of the relay and whether it's fused.
Good luck.

IRAraid

These comments are for a '95 which may differ from your '94.
I checked the manual for a '95 and found that the oil pressure sensor(s) are a single unit with 2 outputs. One to the gauge, the other switches off the fuel pump in case of low oil pressure (<~4psi) after the engine starts.
A blown fuel pump fuse would cut out the fuel pump completely so it's not the fuse. If the fuel pump runs initially, it's not the relay since the relay provides for initial power to the fuel pump.
Sounds like the oil pressure sensor is kaput or a wire is off or broken, or the oil pressure is low (is there enough oil in the crank case???), or the oil pump is dead (not really likely).
There is also the possibility that the fuel flow is inadequate. At the Schraeder valve on the fuel rail, measure the fuel pressure with the key on and the engine off - taking great care to mop up any spilled fuel. If the pressure is slow to build (30psi or so I think) or fails to maintain, then the fuel filter is probably plugged.
Please fill out your "User CP" profile so we know more about you and "your" Corvette.
Good Luck

lefoy84

You are one hundred percent wrong!! There are two oil pressure switches on the back of the engine. One supplies the guage. The other is a backup to the fuel pump relay. If the relay is operating, it is not needed. If the fuel pump relay fails and you have oil press, the fuel pump will be powered through this circuit. This myth rears it's head about once a month. My 86 is this way. My 96 is this way and I would bet the farm that a 94 is this way.

IRAraid

Please accept my humble apology.
I saw one device with two contact sets in the schematic for the oil pressure sensors and mistakenly concluded that there was one device. Going to the component pictorial (or looking at the car) reveals two oil pressure sensors – one to the dash, the other in the fuel pump circuit.

The Helms FSM explanation of the PCM function and fuel pump relay indicates that you’re correct there again.
The manual says that upon key on, the PCM powers the fuel pump via the fuel pump relay and holds it so long as the PCM receives reference pulses from the distributor (opti in a ’95 etc.). If there are no reference pulses, the PCM drops the fuel pump power after 2 seconds. BUT, if the oil pressure switch is closed, that pressure switch maintains power to the fuel pump.

So it seems that if there are no reference pulses (bad lead or flaky opti) and the pressure switch doesn’t close (bad switch, no oil, etc.), the car will run for 2 seconds and the fuel pump will cut off, stopping the engine.
Perhaps this scenario is responsible for the ‘myth’????
Or am I full of it again???
Hope to figure this out.

lefoy84

Don't worry about it, you made a mistake that many others have. I make lots of mistakes. I just try not make the same one twice.

IRAraid

Thank you.

So how do we help this Norwegian with his starting problem?