Hi all. I Finally got my 1990 RS Titled etc (Car lot shutdown in 2000 with the title about a month after we bought it and took 7 years to get a new one.) we parked it in 2001 due to no title so we couldnt drive it.Now I am getting it going again, I am running into a few issues that I cant seem to find a solution for, issue #1 - when its cold, it runs great but has a slight hesitation when you accellerate but its sporatic, once the temp gets to normal (195 F) it starts backfiring through the TBI, the harder your on the pedel, the more it backfires, Ive changed plugs, wires , fuel pump and filter (another issue) also , once its warmed up, if I turn it off, it wont start back up, it turns over but the TBI doesnt seem to let fuel out , BUT if i prime it, after a few tries it will start and run somewhat ok, except for the backfiring, so in essence, the car is driveable untill it gets to temp. issue #2 at one point the hood was taken off and an orange wire was pulled out but i cant seem to find where this orange wire goes, it comes out of the passenger side harness and can reach just about anywhere on the engine..Any ideas on where that orange wire goes? its hot all the time. Issue #3 - Guage cluster, seems almost every guage is wrong, speedo is about 30 to 35 MPH off, 90 = 60 , Tach , basically all the way to the right unless the idle gets to about 500 (estimate) then it goes down to about 6500 - 7000. Temp is ok, Oil Pressure seems ok as well, fuel guage , about 50/50, sometimes its right on , other times it sits at 3/4 when full. I Do have a TPI system with dist. wire harness and ECU from an 86 that i plan on installing when the snow flys. or would this solve some of the issues im having now?

the tach is controlled by the coil. and the back firing could be the coil too, or bad timing. Try timing the car first with the tan wire disconnected (the timing wire), ill look for my book and ill try to find that orange wire.

Thank you for the reply, I Checked the timing today , was about 2 degrees off, not enough i wouldnt think to cause those issues, i am replacing the coil first thing tomorrow,

I Took it out on a long drive today , i noticed , that if i barely give it any gas(after its up to temp), it runs great at 65-70 but if i try to pass (or anything more than about 1/8 pedel etc sounds like a war started under the hood,

I Still have no idea where that orange wire goes, even the GM dealership couldnt tell me. must be a one off type thing?

Coil fixed a few issues actually, it now starts when up to temp, and the backfireing is 95% gone, it still will backfire but it only did it twice all day, this im assuming is timing off (again) so its getting re-timed tomorrow ,

the tach though still does not work, nor speedo, and now the fuel guage is stuck on full which is leading me to think the guage cluster itself is going bad or doesnt gave a good ground?

any ideas where that orange wire goes? ill post a picture of where it comes out of the harness, i took the longer part off as it has a connector on it,


btw thanks for your help.its much appreciated

The orange wire sounds like the hood light wire. Check if its still hot with the hood closed.

I had a similar backfiring problem whenever I was going over 60 in drive. I had new exhaust put on and have not had a backfire since.