1992 305 TBI, engine light flashes, but no code appears when I check it (just 12). Runs very rough, keeps bogging down, tach jumps all over the place.
I replaced the charcoal canister, the bypass valve, o2 sensor, idle air control valve, fuel pressure regulator, and the gas cap but it's still doing the same thing. When I take the gas cap off, there's absolutely zero pressure release. I have no idea where to go from here. The fuel pump is new(ish) and the vehicle will keep running with gas pedal applied, so it's getting fuel. The fuel pressure is just under 12psi, the book reads 9-12psi, so that's good. I know it's a sensor somewhere, but I have no idea what to do next.
The injectors are good and spraying well. When this first started, I figured it was a dirty fuel filter and when I changed it, the problem would disappear for half a day, then start again. That trick doesn't work anymore and the problem is just getting worse.
Any ideas?

 

Running rough with an erratic tach is making me feel it's likely to be a bad ignition module (inside the distributor). That could also be why you're only getting code 12 (no distributor signal to the ECM). You get that by default when the engine isn't running, but your code 12 could be meaning business now, although you wouldn't know it.

 

The flashing check engine lamp indicates heavy misfire, and that is the main reason the engine is running rough. Raw fuel is being dumped in the exhaust, and if you still have a cat, is getting overheated trying to burn it up. In most cases the stuff you changed does not cause misfire. Have you checked the ignition system?

 

Chuck, I didn't realize you were helping Goose6 at the same time I was trying to. Got beat by 2 minutes, dang it!

 

lol. Missed it by that >< much (said in your best Maxwell Smart voice).

 

I've gone through two ignition modules so far. If a third has gone out, I guess I shouldn't be surprised. The last time the car just wouldn't start at all though.
There are some things with the ignition system that I could look at as well. I'll get back to you on that.

The help is greatly appreciated my friend!

 

Moved this thread to the 3rd gen V8 tech section.
The New Member "Getting Started" section is basically new member orientation, not for getting your motor running!

 

92 RS, 305TBI. Car is running really rough, feels like either spark is intermittently going out, or the fuel is. The tach goes haywire and the engine light flickers, but no code shows up when I check it.
Fuel; the fuel pressure is just shy of 12psi, where it should be. I changed out the purge solenoid and the charcoal canister, as well as the o2 sensor. The injectors spray evenly without interruption. When I take the gas cap off, there's no release of pressure, but the gas cap is new as well.
Spark; I changed out the ignition module, cap and rotor, wires, plugs, and the ignition coil.
The problem still exists. I just started it up and it was running rough like there's an interruption somewhere. The check engine light flashes and the tach jumps all over the place. Help???

 

You sound a lot like the guy in the first post!
What does "I've gone through two ignition modules so far" mean exactly?
Same symptoms in the past and a new module cleared it up for a while, or what?
Do you notice a difference in how it runs between having a cold or hot engine?

 

Same guy as the first post. I've replaced two ignition modules in the past 5yrs. There's no difference in hot or cold, it starts out this way immediately. When the problem first started, it got worse as the engine warmed up, but now the engine light flashes, tach goes berserk, and it runs rough right out the gate.