I have a '88 GT with a 3800 SC Series II engine & 4-speed A/T. When I purchased the car, it had a gauge cluster in it that was nearly identical to my girlfriend's 2003 Buick Century 3.1L. The only difference really is the gauge cluster in the '88 Fiero had a tachometer and my girlfriend's Century does not have a tach. I have only driven the Fiero around the yard and a little bit in the neighborhood since I have owned it. The Buick gauges looked so bad in it that I unplugged them a while ago and ran the car without gauges when I needed to move it. It ran fine without any gauges. Yesterday I started to repair the stock plugs for the stock gauges and today I finished up that task and installed a set of spare stock gauges I had.
Now the car starts, but will not stay running. It will start every time, but only run for 2 or 3 seconds before it stops running. It kind of acts like it is running out of fuel, but I added gas to the tank and that did not make any change.
The stock tach is not working, so I am thinking that may be a clue to the running issue, but not sure of that either.

Do you think I may have disturbed some input into the ECM, which is causing the car to kill after it starts?

Thank you for any help and ideas.

[This message has been edited by hdryder (edited 07-04-2015).]

I am by far no expert and have not even started my swap yet. If I was you and the car ran fine before you installed all the gauges I would take them all back out and see what it does. If it runs fine again, I would then install each gauge at a time and see what happens. If one gauge gives the car problems then you would at least know which wires to trace. I read a lot about not having enough grounds. That may be another avenue to look at. Like I said, I'm no expert by far but that's what I would do if I had the same problem. Good luck.

Thank you for that idea, and I wish I could do that. I normally take photos of projects before I start to make a change like this in case I need to refer back to what I had to begin with. But since the car ran well without the Buick gauges plugged in, I did not think putting the stock gauge plugs back to stock order would cause a problem.

Someone has suggested the following:

"Security will trigger injector shutoff in 4 secs on factory setting.
Generally security is turned off on swaps, but there is a chance it isn't."

Does anyone know the best way to turn that off, if it has not been already done on this swap?

Thank you very much for the help on this.

[This message has been edited by hdryder (edited 07-05-2015).]

Could this be 'hardware' added for the 'security circuit' for a 3800 Series II?

I thought it was added and needed for the Buick gauges a previous owner or swap-builder included.

Where do the wires go?

I wish I still knew that.

I normally take photos of projects before I start to make a change like this in case I need to refer back to what I had to begin with. But since the car ran well without the Buick gauges plugged in, I did not think putting the stock gauge plugs back to stock order would cause a problem.

I just traced back the one new wire added by a previous owner, that I had no place to connect it back to for the stock gauges. It is straight spliced into the brown wire of the DLC, which has been relocated under the dash on the passenger side, just to the right of the radio.

[This message has been edited by hdryder (edited 07-05-2015).]