I was driving on the highway at about 80-85 mph when the ses light pops on and the gas guage dives from 1/2 to 1/8 tank.
I pulled into autozone parking lot to pull codes, nothing.
new plugs, wires, cap, rotor, ignition control module, all new vacuum lines, new brake booster, new y-pipe back exhaust. When I started the car up from Autozone, the car bogged, sputtered, then died. I ended up pushing it a block to a gas station about a block away. It only took 7 gals.
Then started right up. What the hell?

 

When you mention the fuel gauge dropping like that , It leads me to wonder if something put a massive electrical drain on the circuit , as in something shorted out , and then took out a fuse that may have left some engine system or another not functioning . I don't know of any connection between the fuel gauge and the ECM , so whatever the problem is it's gotta be fairly big to affect both .


As a little electrical side story , , , when I bought my car , at random different sensors would trip trouble codes that mostly wouldn't come back once reset . It finally got bad enough for a look around to find the problem , and what a problem it was ! The rearmost bolt on the exhaust manifold had fallen out (as seems common with our 6 cyl engines) and was allowing hot exhaust to blow right onto the wiring harness that was nearby ! All kinds of wires were melted together , and I'm amazed that it ran at all !

A rewire was done , as well as the missing exhaust bolt taken care of , and no more weird electrical gremlins have been observed .

Have you checked your harnesses , especially the underhood ones , for problems like this ;

 

Is the check engine light on and you not pulling codes? You said it was on but you got no codes at AZ?

 

weirdddddd.... sounds lik possibly a fuel pump/sending unit/ wiring problem

 

The fuel in the gas tank was boiling. Caused a lack of fuel pressure and the gauge float to drop. Adding fuel to the tank cooled it to stop it from boiling. There is a long thread about this issue on the TPI board here.

RBob.

 

Thanks for all the replies.
Missing a few exhaust studs ( po snapped the heads off flush with manifold) wiring looks fine.
the boiling gas sounds like what it was but the muffler to tank heat shield is in place ( trust me working on the muffler I hit it with my wrist, 3 stitches later ……)
How would I check and cure the boiling gas?

 

The bolt heads likely broke off by themselves. This is a common issue with these engines. Consider it lucky that it is flush with the manifold and not the head. Should be able to pull the manifold off and use vise grips to back out the broken ones.

As for the boiling fuel, some advocate adding, IIRC, diesel fuel to the tank. Just a 1/2 quart? Here is the thread:

https://www.thirdgen.org/forums/tpi/...regarding.html

Other then the diesel (kerosene maybe? It is in that thread), no one has been able to fix the issue.

RBob.