I have(had) a 91 RS with a v6. I put a 350 TPI in it. The engine + wiring harness + CPU is from an 87.

Heres my situation I am so close I have 3 wires left! and just cant seem to figure this last thing out. I turn the key and the engine turns over wants to start but does not stay on(not sure if its because power going to computer or something). The fuel pump does not turn on by key.

I am using the bulkhead connector from my 91 and just cuttin the bulkhead off the 87 and putting it to the matching wires from the 91 Bulkhead. These are the few wires I have left. And The problem I am having is the fact that the fuel pump will not turn on by key, it turns on when i connect direct hot to the (G4-GRY wire) on the bulkhead. So i know the fuel pump works but where do i have to run the GRY wire to on the 87 Wiring Harness. Also what wire controls spark??

91 Bulkhead Wires
G4- Fuel Pump(Gry)
A7- Emissions Control(PNK/BLK)(???? is this even needed????)

87 Bulkhead Wire
G7- Computer Command Control(???? is this even needed????)

I will be checking my messages tonight(Nov 9th) and early tomorrow (Nov 10th) around 4:30-5:30a.m. after that I wont be home until either saturday or sunday, the car is at a guys house that i work with, i will be there working on it and finishing up odds and ends, if you figure something out or have any input/tips after Late nov 9th early nov 10th. i would really appreciate it if you could give me a call my # is 1-860-268-4007, i work 6-2:30, during the day i can answer the phone sometimes depending on how busy i am, if i dont answer just drop a message and i will call you back

Thomas

 

Ok, let's take a look at it. Fuel pump first.
If you put +12V on the grey wire, fuel pump runs. Good.
- Look at the fuel pump relay under the hood. Does it have constant power to the orange wire? If not, check the fuse by the battery (for fuel pump, fans and ECM).
- When you turn the key, does the relay click? (if yes, ECM is controlling the relay and the problem is in the relay or its wiring)
- Check the relay ground (black/white). Put a probe on the fuel pump actuation wire (green/white). Turn the key. If no light, then the ECM is not controlling the fuel pump. Either a missing wire or problem with the ECM.


"Engine turns over, wants to start but does not stay on".
- Hmm, how's your VATS? If you previously disabled it in the V6 PCM and now are using another PCM that doesn't have VATS disabled, that would be a reasonable source of a problem.
- If you put +12V on the grey fuel pump wire and let the pump run, the car still doesn't start and stay running?
- Put a test light on one injector (between both wires). When you're cranking, does the light flash a little (it would be probably very dim). Once the car starts, can you still see the light flashing? When the engine starts dieing, is the light still flashing? That'll tell you whether the ECM is injecting fuel.


Spark:
- put a test light on the white wire on the coil. When starting, the light should be flashing. Same test with the injectors. Watch the light closely to see when it stops flashing. After the engine dies? Then it's probably not the spark.


Once you test all the above, you should have a good idea what's wrong with the system.
Let us know what you find.
Lou

 

1. Pump relay has constant power on orange
2. Turn key Relay Clicks, Power goes In relay and out of relay.
3. Will be checking that soon, dont have access to computer where we are at.

4. VATS was never disabled
5. When i put constant power to the fuel pump it stays running, never shuts off. And no the car does not stay running, the grey wire from the ignition is not connected to the directly to the engine harness anywhere or going back towards the ecm, i dont know where or what wire to hook it to on the 87 harness.
6. again will be checking that asap! and will respond with answer asap

7. again will be checking asap, i called my friend and if he has a chance he will check these few questions taht i have not answered and let me know whats up if not i will know and have it posted by monday, i will be at his house tomorrow morning and stay the night.

Found more things to find out....
I have a gm code tester and im getting code 12 which just says it works i know that. And im getting Code 54, those are the only codes im getting and i know code 54 has to do with the fuel pump, any ideas?? its probably cause the gry wire from the ignition is not hooked to the 87 harness correctly because we just have it constant feed to it.
CODE 54-Low voltage at fuel pump OR Low voltage at Fuel pump relay OR Output failure at quad driver module

91 Wires from bulkhead connecto
G4- Fuel pump wire(gry)(still dont know where that goes to the 87 harness)
A7- Emissions control(pnk/blk)(still dont know where that goes to the 87 harness or if it is even needed)

87 Wires
G7- Computer Command Control(This wire was connected to the 87 bulkhead but i do not see anything on the 91 bulkhead that relates or is the wire, any ideas what wire on the 91 bulkhead it would go to?)
F5- Multiport Fuel INJ(DRK GRN)(this wire was connected to the 87 bulkhead, and where it runs on the engine i dont know where it is supposed to be connected, it was just hanging in the breeze, so i dont know where it would connect to on the engine or in the 91 bulkhead)

The car does fire in start mode, but when i let go of the key after holding it to start, engine does not seem to fire to stay running. When holding the key, engine fires + starts up for a second and keeps firing like its starting until i let go of the key and let it drop into the run position, then it does not fire/run at all.

 

bigbabylou i think the problem is in the c207, c221 connector for the 87 harness, i need pinouts of the c207 and c221 for the87 and pinout for the 91 v6 207

 

You said that the FP relay clicks and power goes in and out. If it goes out, it better be going to the grey wire. Yet but FP doesn't turn on? So when you put +12V on the grey wire to run the FP, where do you do it? Which part of the grey wire? This would point to a problem in the wiring.

Sorry I haven't been around all weekend but it was a very busy weekend, working on others' cars. I actually just got home and I'm working on my car for a change.

Try PM-ing Trickster for the pinouts. Do a search on the C207, you should be able to find it here or through google (I remember seeing it somewhere on TGO).

If you need, I'll be home most evenings this week so feel free to call me. I PM'd you my number.

Lou

 

YEAAA BABY!!!! i got the engine to run!!!!! i wired the fuel pump threw the fuel pump relay output, a there are a few things left that i have to figure out.

1. The Cooling fan does not turn on, ill be able to figure that out or ill just make it so it turns on by the key
2. Going from the 91 bulkhead out, the torq converter clutch(auto overdrive) where does that go to on the 87 harness.
3. On my v6, the fuel pump made the humming sound when u turned the key, then it shut off, the way i have the fuel pump wired now on the v8 87 harness the fuel pump stays on all the time, but when you turn the key its a louder humming then it dimms down to a lower key humming, is it supposed to ever stop?
4. On the 91 bulkhead going out, my Inflatable restrant(blk/wht wire) where would i hook that to on the 87 harness?(not needed but figured id get it hooked up the right way)
5. And the 87 harness had a wire called computer command control that went into the bulkhead but i can not seem to figure out which wire it would connect to for the 91 bulkhead or if it is even supposed to run threw the 91 bulkhead.

I believe thats it, i forgot the list at his house but rest of the stuff is not "manditory" to have the car run and can be done at a later time.
When that car fired up we both almost hit our heads on the 12' ceiling cuz we were so excited and it was wicked loud!. My only advice to people who does the v6 to v8 swap as of right now is make sure you have a lot of time, Diagrams of both engines wiring connectors c207, c221, Computer, And Bulkhead(c100) connectors. Another big thing would be to get an engine from the same year so the wiring is almost exactly the same!!!!! so you dont have to trace wires for a week straight and figure out what goes where and oh this connector isnt even on my 91! lol

If anyone has any answers to those following questions, i will not see the response until thursday or friday, so if you would be so kind to give me a call my phone # is 1-860-268-4007, if its long distance for you, we can hang up and i will call you right back.
Thanks everyone
Thomas

 

The A7 on your 91 C100 powers the Air Select and Air Divert valves, the Canister Purge Solenoid Valve and the EGR valve.

The 87 does not use the C100. Instead, it powers these through the C207, pin G. Check the wire color there.

Just gimme a call again tonight, I should be home, I'm not going to the races tonight.

Lou

 

Original poster you have a PM.