88gt Terrible idle and real rich

[hotrodford67]

I changed my speedometer cable yesterday on my 88 gt , all appeared to go well but when i fired up the car afterwards it was running terrible. Appears to be real rich as there is lots of black smoke. I checked to see if i had dislodged any wiring in the process of the speedocable change but cannot find anything wrong.
Anyone have any ideas, what could I have disturbed that would cause this ?.

 

[BlackGT89]

Not that it's related to your speedo cable, but pull the vacuum line going to your fuel pressure regulator and see if there is gas in the vacuum line. If so, you need a new fuel pressure regulator.

 

[DW5.0L]

Man that is a strange set of symptoms related to a speedo cable swap. Especially if the car ran great before touching it. Make sure all plug and cap wires are snug.
Check the timing and or compression. If all checks out good, pour some SEAFOAM in that pony and decarbon the engine and clean the injectors. Good luck solving it.

 

[hotrodford67]

Thanks for the answers so far, I'll check the fuel press reg, and go from there , car ran fine before I got my mitts up in the dash and rooted around cant help but think I caused it but it may well be a coincidence.

 

[jrichker]

Did you knock the vacuum line off the MAP sensor when you routed the new speedo cable down the firewall?

 

[hotrodford67]

Thanks all for your input.
Fixed - vacuum line under rear of upper intake to sensor on firewall , i guess i knocked it off and couldnt see it in the evening light as it had made its way well out of plain sight. - A couple more of these vacuum / sensor events and I'll be ready old school this puppy with an torker intake and a 650 holley.
larry