Hey anyone. I just purchased my 1986 pontiac firebird trans am yesterday. It runs, but not perfectly. I was planning on replacing the major electrical/engine harnesses first. But I'm really trying to get advice on mechanical things I should replace to help it run better. If there's already a thread for this, a link to it would be nice. I'm looking for the most important parts before less important parts. And I'm not interested in interior design just yet. The car has a new alternator, flow master exhaust system, starter, and battery. And it's an automatic in case anyone was wondering. Thanks!

 

Hello pattydatwo , welcome to Third Gen . Org

So I gotta ask , why are you considering replacing the car's wiring harnesses ?

Really the only two things that can damage the car's wiring harnesses bad enough to require completely replacing them is either a wire fire melting/destroying the harness (this usually follows someone with just enough electrical knowledge to be dangerous jumping out the fusible links or putting in higher amp rated fuses than are supposed to be there) , or , some dolt with even less electrical knowledge and a pair of wire cutters decided to cut up the harness for whatever inane reason hacks like that seem to find to butcher these cars ("Gonna get rid of all that EEEevil emissions crap and turn it into a racecar") .

 

I just wanted to replace it before it died on me so if it did die on me it wouldn't be at an inconvenient time or damage any other systems in the car. I'm really just trying to do that with any older, part that I can replace. In short: I want to fix things before they fail.

 

Hopefully that helps!

 

Ok , so , just so you know , the car's wiring harnesses are not regularly replaced maintenance items like spark plugs and spark plug wires are . If the wiring harnesses haven't been burnt or hacked they WILL last pretty much forever , VS the "tune up items" like the plugs & their wires , the distributor cap & rotor , the fuel and air filters , and so on . Unless your VERY rich it's just not economically feasible to replace EVERY possible part that could fail , your plan should instead be to do all of the usually neglected maintenance items , replacing any presently defective parts along the way , and then drive and enjoy the car while you handle any parts replacements that pop up .

 

Thank you very much. Do you have any advice for converting the old gas measuring system with a more modern one? The one on my car is broken and only shows it being full. Also also, my speedometer is broken. The people that owned it before the person I bought it from disconnected it, is there a connection port? If so where?

 

The gas gauge problem could be either the gauge unit itself , the wiring connecting it to the sending unit in the fuel tank , or the sending unit itself . The sending unit (being a mechanical device and subject to wear) is the usual "most likely suspect" , which should be determined by proper troubleshooting technique before being replaced to make certain it's actually bad . As to your speedometer , your car being a 1986 should have the mechanical VS electronically operated speedo , look at the transmission's tailshaft housing on the left hand (driver's) side to see if a black cable is connected there . If it's connected at the transmission it could be disconnected from the back of the speedometer .