Good call, I was about to write it off as bad gas and drain the tank. I haven't replaced the fuel filter yet, that's next on my "to-do" list for the car, probably this evening or tomorrow most likely. How the hell do you get wrenches up in there to do that? I was planning on getting the bottom fitting loose, then removing the snap-line up top and the clamp that holds them - removing the filter and the supply line all in one out the bottom (or top?) then replacing it on the bench.

The tank "hisses" when I slowly open the cap. I'm assuming this is normal since it's always done that since I've had it (about 4 months.)

I went outside a little bit ago and ran it - it's somewhat driveable, but I don't trust it NOT to die when I come to a stop, and I'm not comfortable with trying to get it started again (even though I do have AAA.) I got it up to temp (180) and it runs exactly the same cool as it does at warm. Makes no difference.

 

the cap hiss is normal.. jusr check the line that goes to the purge solinoid just behind the thorttle body on the passenger side of the engine (under the fuel rail cover). That little rubber line likes to clog up with charcoal as the miles rack up and these cars age.. I disconnected that hose fronm mine and blew it out with the compressor (by disconnected I mean I removed the whole hose form the car.. do not blow it back into the canister.. this is bad). The other end of the hose is down near the washer fluid reseviour (sp). As for the fuel filter.. it is somewhat tricky.. I think i ended up dropping ym exhaust to get to it.. I'm sure others will chime in..

racetronix.com has fuel pump kits with everything (and I mean EVERYTHING) you need to replace with a walbro 195 l/hr fuel pump and new sock for $99.00 its tough to beat. But first check to see if your fuel filter is clogged before you start taking the pump and filter sock out of the tank..

hope that helps.

 

Update: Changed the fuel filter this morning (rained all day yesterday) and it still runs like crap. However I managed to replace the fuel filter without removing the exhaust.

Now the battery is dead though, after all this starting and no charging; so it's on the charger now.

I did find one spark plug wire that had popped off but I put it back on, not much difference. However, the fuel pressure is UP where it should be, around 40 but I can't keep it running long enough to look over and see the gauge.

I also took a sample of the gas, to see if there's any water in it - how long do I need to wait to see if the water seperates if there's any in there?

 

IT RUNS!!!!

I have NO idea what fixed it - I charged the battery up and put it back in, but while I had the hood open I jiggled the EGR ever-so-slightly and it fired right up and ran wonderfully!!!! I drove it probably 20 miles and it's back to normal. It idles a teeny bit rough (just barely noticable) but runs super smooth and accelerates just like it used to.

I'm at a total loss.....

I'm going to replace the EGR as a matter of course; about a month ago I got a code for the EGR but it went away so I ignored it. Wondering if it has just enough "gunk" in it to keep it from closing fully..?

 

EGR in itself wouldnt cause your symptoms.. However, running 11 psi less pressure than required would do it...

I think it was your fuel filter... sorry you had to go through so much for that... Happy trails!!!

 

Congratulations!

Just some additional info, the EGR is vacuum driven and has no interface with the computers to throw any kind of code. It is vacuum driven which gets its vacuum from the EGR solenoid which is basically a vacuum switch which is operated electronically. When the solenoid is energized, it lets the vacuum pass and it is applied to the actual EGR valve.

Now, that circuit is monitored which has the capability of producing a code. So saying it another way, the PCM monitors the electrical part of it, but the vacuum part is not monitored nor is the EGR valve.

If the EGR valve was stuck, that would be a mechanical thing. I just have a hard time making the connection of that problem causing a rich condition as we all have been talking about.

Just some other foolish thoughts. With the battery removed the ECM would have been re-set from the power down and might have made the difference. Or, you could have bumped the connectors on the PCM (while changing battery) and something could have made contact.

All this stuff could be nothing, might just want to keep it for thought.

 

Drove it another 20 or so miles this evening, still running fine.

I'm thinking the EGR might have stuck slightly open causing it to run crappy. Also, the lack of fuel pressure and repeated cranking may have fouled the plugs out (intake pressure rises, so does fuel pressure.)

Will probably pull the EGR tomorrow and soak the bottom in carb cleaner and clean it up.

As for going through all that, I was planning on doing it anyway since it's all "unknown" to me - especially the Opti.

Thanks again guys for all the help!

 

Well ****. It's back.

I went to the store (about 15 miles away) and got back in it, and it started acting up again.

Had to feather it to get it home, bucking if I went below about 1500 RPM. Idle at stoplights, I had to put it in nuetral to keep it from dieing.

Got it home, checked fuel pressure - around 38-39 PSI at idle.

Pulled the negative battery cable for about 2 minutes, put it back on, and it runs just fine. Still, no SES light. Could it store codes without the SES light coming on? The SES light comes on at key-on (bulb test) so I know it's working.

WTF?!?!?!

 

Time perhaps to try an ECM. I have read more stuff about 92, 93 ECMs causing all kinds of weird symptoms and I think you are starting to fall into that mold.

 

So a good friend of mine dug up this page:

http://www.corvettebuyers.com/c4vettes/codes.htm

And I did the "A" - "G" test, and it showed up with the usual code 12 (normal) no codes for module 4, but module 9 showed up with H62??

Of course, this is after I reset everything by disconnecting the battery so when it does this again, I'll do this same test.

 

H62 is a (historic) tachometer data error in module 9. Unlike module 1 (CCM) and 4 (ECM), disconnecting the battery will not clear module 9, the brake computer. So you need to clear it using the on board diagnosis going to module 9.7 and clearing the errors.

When you disconnect the battery, it does clear the ECM which might be a big clue here to what the problem might be.

 

That may be from when I had put the Accell 300+ box on and didn't remove the tach filter yet. It was acting squirrelly and threw a "SERVICE ASR" light on the DIC.

So today, is even worse. Decided to go see my grandmother, and the car died about 5 miles from her house. Was on the freeway going about 65-70 or so, when the motor just died. Can't restart it, and disconnecting the battery does nothing. Tried to pull codes and nothing; just the C12 and H62. Thankfully, I have AAA and just had it towed to her house.

Going back over there in the morning with tools to see if I can figure it out. Cranks, but won't cut over - not sure if it's fuel or spark. I went through a big rainstorm to get over there, but the opti is brand new and has the vent mod on it so I'm not willing to say it's spark (just yet.) I'll test that tomorrow.

Probably build myself a computer interface here this week to see if I can get something like Datamaster to talk to it and see if I can see anything odd.

 

With my back hurting like it is I opted to look at the simple things first; so I checked the fuses and come to find out the COIL fuse was blown!

I guess since the Accel 300+ uses a little more juice than the coil by itself, it blew it out, so I put a 15a fuse in place of the 10a fuse. (The Accel box is powered from the coil connector.)

Now to chase down the crappy running over time. I'm going to see about replacing the O2 sensors - read up on how to do that so we'll see how that goes.

 

How's it going on your '93?

I'm not sure if the O2 sensors are your problem, but I just replaced mine in a '96. Pretty much cake. I also used the Autozone tool loan program for the O2 sensor removal/replacement. It had a couple of extra sockets and wrenches which helped get into the tight place they are located. I'm glad I used their tools because of this.

 

Was just going to post, surprised to find this on the first page again.

I haven't replaced the O2 sensors yet; been looking at simpler options first.

I figured out the Accel 300+ box had some water in it, so I completely re-did the entire harness, cleaned out the box, eliminated the unecessary intermediate connectors, put shrink wrap all the way into the box and then put silicone around the exit and put corrugated split loom with friction tape around the entire mess. It looks factory and you can't even spot it unless you know what you're looking for.

Started the car up, ran OK but was still acting a little funny so I put the dash on the coolant temp, and watched the coolant temp jump around a bunch. Went back home and pushed the connector in a little tighter and now I get steady perfect readings - I figured I had fixed it.

Until this morning, when I started it and after about 3 seconds, poof; it was running super rich again; I ran behind it and could see it poofing black smoke out the pipes. I shut it down, disconnected the battery for about 2 minutes, and now it runs perfectly AGAIN.

In the posts above, a couple of the guys mention a new ECM; I went to NAPA today to see if they had one and they said they'd have to *send it off* which I wasn't too thrilled about, so I started looking online and found Rockauto has them for $150 + $150 core. However, while looking at the further information it said this:

I'm no stranger to ECM's by any means, so I'm going to pop it out and take a look at it. If it's just the conformal coating, I can probably do that myself.

Oh, I also bought a nice molded ALDL cable and I'm going to make a nice OBD1 cable that'll read all my cars (including my grandmother's carbureted 1984 Carprice.)

 

Took a few pics of the ECM..

Here's where I popped it apart. It took a little bit of careful coaxing, but I had unscrewed everything - turned out to be glue (hot-glue-like) that was holding the inner ECM workings to the outer shell. There's a green O-ring around the edge where the connector is.



I put it under the microscope (B&L 3x stereo microscope I have for soldering on ECM's and other electronics) and looked at all the connections I could get the scope over. Every connection seemed to be nice and clear.



I'm going to build up the ALDL cable and see if I can replicate the issue with Datamaster on it.

 

Nice pics.

Did you ever test out that EGR valve? If not, one simple way to 'bypass' it to see if it is an issue, is to unplug the TOP vacuum tube from the EGR. Then, put a peg or golf T into the end of the long vacuum tube you just unplugged. If your problem goes away, your EGR valve is at fault.

I don't know, maybe the problem is a lot deeper than that. I wonder what is causing your rich condition. Have you had someone put a scan tool on it? It may pay to have that done, if you haven't. This way, you can check out your O2 sensors, too. ...and a lot more.

 

I did pull the EGR (and my back out.. OUCH) but it appeared to be working normally. I put vacuum on it and it moved back and forth. I also cleaned as much of the carbon deposits off as I could. I don't suspect it anymore since I can disconnect the battery and reconnect it, then it drives just fine.

As for putting a scanner on it, that's what the ALDL cable is for, I've got TTS Datamaster downloaded onto a laptop, and I'm building my own cable.

 

I think your 300 box fouled the plugs causing it to still run like sheiot when you removed it and the rich mixture may crapped the O2 sensors
and the cats hate that too
Just my .02

Did it ever throw any codes?

 

Never threw any codes.

I don't argue your points at all, but what boggles me is how it runs GREAT for a few days, then POOF I start it up and it runs like crap all of the sudden. It's literally like a switch someone throws. No gradual symptoms, nothing.

I drove it today, but I did remove the ECM last night (which of course disconnected power.) It ran just fine.

Does anyone know if these ECM's are filled with any gasses? When I took the first screw out it went "psssssssssssssssssssssssst" like it was filled with something (assumably an intert gas like nitrogen) to prevent moisture?