I dropped my fuel tank to fix a leak in my 89' TPI Iroc. Once I put the tank back in, I fired it up without adding any gas to it, so my friend could hear it with the exhaust off. After I finished putting the rear back up, and everything else, I poured in the gas that I had drained out. heres where the problems start:
* It has really ruff idle,
* when in gear it dies at stoplights, and stop signs
* cars runs excellent at WOT.

I added fuel stabalizer thinking that there was water in the gas, because the car smokes a little white till i added the stabalizer.
Reset the timing, and it didnt help. Added a bottle of Lucas fuel injector cleaner, and still runs like crap.

 

Check your ground wire from the fuel pump, that may not be your problem but it happened to me once and I fixed it by grounding the ground wire.

 

okay, now it will die if im cruising at say 40 and slow down for a stop light, bam it dies. It hunts for an RPM at idle, like a vaccum leak, but is pulling 17 inches or whatever vaccum at idle. If you drive with the throttle in the same position, you can feel the car surge forwards every other second or so. And it alot of preignition, tried replacing my custom chip with the stock one, no use.

 

If all you did was drop the tank and put it back up, that is where you need to start looking.
Fuel lines, did you hook them up properly? Pump, did you remove it? Check the electrical connector for the pump/sending unit by the tank. Check the little plastic tank vent mounted up near the filler neck. Make sure no lines got bent/kinked. Check that no hoses are pinched.

 

That does sound like a vacuum leak.... did you disconnect the battery to do this job?

 

Start with a fuel pressure reading. That new filter you installed when you had the tank out may have already been plugged with the debris that was shaken loose by removing, handling, and installing the tank.

What? You DID install a new filter, right?

 

i dropped the tank to simply fix a leak, which once the tank was down we could find no leaks, yes i hooked the fuel lines back up correctly, but does anyone know the number for the breather/filter that is right back there next to the tank? I am going to put in a new fuel filter tomorrow afternoon, I will also get pressure readings tomorrow at school. I did not unhook the battery when i did this job, and i did not remove the pump from the tank.

 

maybe the fuel pump pickup fell off the pump?

 

No pickup on a FI pump, just a screen filter at the bottom.

 

ahh i see.. thanks for the info. i've never opened a FI tank before.

 

hooked it up to the snap-on scanner today at work, it didnt show any trouble codes, everything looked fine, IAC steps were around 57 at idle, 21 degrees advance on the spark. I went into the trouble shooting portion of the scanner,and chose rough idle, stalling, and rough running. It said to check the coil/ cap/ and pickup or something like that, how do i do this? is it listed in my chilton manual?

Thanks

 

Coil, cap and rotor, simple tuneup items. Yes it is expalined in a Chilton's manual.

 

So, did you get that fuel pressure reading yet?

 

ill grab it when I go in to check the resistance on my ccoil. Hpw much pressure should I have, i checked it in january, and it was only around 38 when running.

 

That should be a good pressure at idle with the vacuum hose connected the the regulator. The factory spec is 37 PSIG, ± 3 PSIG. My concern is that you may not have the same pressure you did back in January.

 

didnt get a chance to throw a guage on there, but I think my neighbor has one that I can use.

 

Took the car, and the laptop over to my friends house, he just got back from an automotive school in phoenix arizona. He said that BLM's above 128 are rich and below are lean, i thought it was the other way around? He also said that everything looks good, so he thinks i just dislodged some crap into the pump, and thats why it makles the wierd noise, and he thinks its starving the engine for fuel, does this sound right?

 

Low BLM is rich, high is lean, he has that backwards.
It is possible that you did get some crap in the pump..if the sock strainer isn't in place. If your pump was never replaced then I'd bet the strainer has disintegrated and the pump is picking up junk from the tank.

 

pump was done 7 months ago. I got to reading about the BLMs and i can see where he got it wrong, if its lean then they read above 128 cus the computer is adding fuel, if its rich thenit reads below 128 cus the computer is cutting fuel out.