89 RS Camaro 305 TBI, AT:Hey Fellas, Here is my problem! I cant get my fuel pump to come on unless I direct wire 12v to the tan& white wire at the F/P relay or jump it from the orange wire on the relay to the tan & white. The pump will come on either way and if I hook 12v to the aldl at the G connection it will come on. I tested my green/white wire at the relay and I have (.97) volts when I turn the key on. It doesn't give me more than that even from initially turning the key on for the 2 seconds you would expect 12v. My question is how do I test the ECM, and can Vats which is supposed to send a signal to activate the ECM fuel relay be doing it? And how would you check that. My security light goes off after about 3 or4 seconds so I was thinking it could be the ECM and not the VATS but I don't know how to test it. I have checked all my fuses under the dash and the fuse beside the battery. Any help would sure be appreciated and thanks ahead of time for your input.

 

https://www.thirdgen.org/forums/tech...formation.html


VATS shuts off the injectors and the starter, has no connection with the pump relay

Is the voltage the same with the engine running?

 

I

 

Just so you are on the same page as everyone else ;
Not " cranking" means the engine is not turning over

The motor is cranking if it is turning over on the starter.
What you are supposed to say is it won't fire up

That test will determine whether the ECM is not operating the relay at all or not operating the prime function only

Is the OP (fuel pump ) switch that runs the pump as a backup to the pump relay wired and working?

If it was ,the pump should run almost as soon as you crank the engine over

 

Sa

 

As I stated ,in automotive circles like on here
cranking means the engine is TURNING OVER on the starter ,
not firing up and running.

Your statement should have read,
"it will crank over but not fire up and run until I spray"

 

Never Mind

 

Shorted wire

 

Why have you deleted all your smart a*se comments to someone is trying to help you solve your problem?

 

You talk real nice! It is best to leave well enough alone! That being said " Have a nice day".

 

Weird, I've been fighting the same damn thing. Car died the other day, no fuel pump kicking on. Got out the shop manual, put 12V to the test plug underhood = nothing. 12V to circuit 120 (Grey wire) out of the relay still nothing. Got under car and put meter on the female end while dad turned key, 12V for 2 sec like should be. Figure ok, pump shot. Replaced it, drove it around town a bit..cool fixed. Got in the car this morning heard the pump prime and started down the road to work...and pushed the car home. Didn't even make it 1/4 mile. At lunch break I jumpered 12V to the test plug underhood and its humming away. Had mom turn the key to try and start it while I held the pump on and still wouldn't start then heard the FP relay chattering away. Ran out of time but plan on taking the fan relay right there and putting it on the pump plug and seeing what it does. Other than that I guess I'm down to tracing wires too. So which one did you have shorted?

 

If the factory OP switch as shown in post # 4 above is installed and functional the pump will run independent
of anything the relay is ( or not ) doing as soon as and as long as the engine has oil pressure
That is the factory pump backup should the relay fail

The OP switch uses the same wiring to the pump as the test point you successfully used.

 

Hey Kojote, My tan wire at the OPS (oil Pressure switch) just above the oil filter looked like someone had cut it and then splice it back together and it had come apart. I put it back together and still had no power running to that wire when turned over so I changed out the OPS and it now works where the fuel pump will come on at the tank. The orange wire at the OPS had 12v the whole time! Check your fuse by the battery and see if it is blown. I assume you have one in the same place as my 89. If you run 12v to your ALDL at pin G(lower left) and your fuel pump comes on that is supposed to mean that your relay is good. Check and see if you have 12v going to the orange wire on your fuel pump relay and if you don't that means the fuse by the battery is blown. The orange wire supplies power off of that fuse connection to your fuel pump relay and your OPS by the oil filter. The tan and white wire comes from the fuel pump to the relay and the OPS so if you jump the orange to the tan and white on the relay and then do the same to the OPS and the fuel pump come on the OPS itself may be bad like mine was. I hope this helps you and let me know how it turns out.

 

No
That only tests if the pump is working ;why it is called pump test terminal.

If you could read a circuit diagram, you would see that terminal G goes through the N/C contacts on the pump relay
when it is turned unpowered so it is no indication that the relay works or not.

 

I can read just fine! I do not have a diagram and so I was going off the word of a mechanic I spoke with.

 

That is why I put up a 3rd Gen pump diagram for you in post # 4 above

Time for a mechanic who understands how a relay works

Give him this
http://www.the12volt.com/relays/relays.asp

 

I appreciate that. I did not see anything in the diagram on post#4 about the g terminal. And that is true that I do need to find a knowledgeable mechanic. That is mostly why I am on this site. The terminal g from what I am figuring in post 4 must be the red wire off of the relay but it is hard to see in the post. All I see is the word connection but that would be the logical place. I have not looked at the inset you sent yet but thanks for your help in letting me know how it works.

 

I see now in post 4 that you can hover over your image and get a prompt to enlarge for full diagram. Thanks for your help.

 

From a Vette TPI car but wired the same


]

 

Thanks a lot! That sure does help with some of my questions!

 

Well I'm more confused now. Got back to my parents and unhooked the battery for a while and hooked it up. Like magic it started right up. Beginning to question the ECM. Nothing in the fuel pump diagnostic section helped. It basically said if the pump runs when jumpering the under hood test point its all good. But this thing sure isn't acting all good. Now, dad pointed out that the first time this happened and we thought it was the pump the battery was unhooked during change. Today it was just unhooked a while. I can't think of anything except the ECM that would be effected by that. Guess I'll see if it does it again and try that again.

 

Oh and if it would help out I can try and scan in some diagrams for TBI if it would help anyone.

 

Just wanted to say that on my 91 with vats disconnected, it wouldn't allow the fuel pump to prime.

 

If that was the case you had other problems.
VATS has no connection with the fuel pump.It disables the injectors and starter only

 

I'm confused
In your 1st post you said you had the pump running by jumpering it and the car would still not start which would lean towards a non fuel problem or at least not pump related?
FWIW.
If you have a working OP switch then the pump will run as soon as you crank the engine over regardless of anything the ECM may or may not be doing with the pump relay.The OP switch is wired in parallel with the relay , see diagrams above

 

I don't think it's a problem. My wires are different colors compared to all the other thirdgens as well.

 

That makes sense thinking about it, and I suppose over the sound of cranking I wouldn't be able to hear the pump kicking in back there. So that brings me back around to why did it die/act up then and speculatively clear up after removing battery power. Which is why I'm now contemplating ECM.

 

I do, because VATS / Pass-key has never had anything to do with fuel pump operation.
Show me the VATS circuit diagram for your year that shows it does ?

 

Could be any intermittent problem
Until you have identified it as a fuel or spark problem you are just guessing

 

Oh Im not going to deny I'm just guessing at all. I'm just wanting to get it working. Already fought one issue last month where injectors weren't firing. Narrowed it down to pickup coil. Replaced that and the ICM while I had the distro out since it looked like it had been getting hot. And ive replaced the rest of the ignition system over time so I'm fairly confident in that. Whatever it is I have a feeling its going to be something odd. Hell everything about this car as long as I've had it has been lol.

 

I wish I had a diagram, it would've made bypassing vats easier. Idk why it's different on my car, but it is. It doesn't even have the TPI fuel pump in it anymore so like I said, I don't see the problem.

 

Here are the diagrams for a '92 PassKey.

 

So your car is not factory stock then , all bets are off.

Anything could have been done to it so your original comment ;
""on my 91 with vats disconnected, it wouldn't allow the fuel pump to prime"
is irrelevant to this conversation and just adds confusion

As you can see from the STOCK Passkey circuit diagrams Kojote posted above , the fuel pump does not appear anywhere

 

So when it happen next the 1st thing you do is pull a spark plug and see if it wet or dry
Wet ; no spark ( in the cylinder )
Dry ; no fuel. ( in the cylinder )

At least knowing that will give you a direction to fault find , instead of just stumbling around in the dark

 

It was factory stock before I changed the fuel pump and swapped the engine, which was when I found that disconnecting vats disabled the fuel pump.