Hi Guys! I just bought an '89 Iroc-Z vert. It has a 305 TPI motor/auto trans. about 84,000 miles on it. A little background, the poor baby has been sitting in a garage for the past three years, only being driven out and about for a short period every couple weeks. Recently the gentleman I bought it off of said it started to miss and developed a crackle in the radio. (No service engine lights to be had...) I had some mechanic opinions that it was possibly due to an ignition problem. So I brought it home. Once it reaches my driveway it dies and I can't get it to restart (isn't that always the way it is!) So I put a new starter in it, the car fires back up and runs great till it heats ups. Then the engine starts to miss worse and worse till finally you shut it off and it won't restart again. (also the rpm drops way down almost to stalling range when you come to a stop.) So digging into it I changed the distributor, put on a new cap & rotor, changed the plugs and wires, (at this point I'll note that the plugs all looked great except the back two on the passenger side - they were both pretty black with carbon residue.), and changed all the fluids. The car runs 100% better, but as soon as you've taken it for a drive, shut it off, and started it back up again it starts to run rough, then will die and won't restart till hours later. So today while mulling it over at work I decide maybe I'm chasing the wrong end and its a fuel issue, not electrical like I first thought...so back to the garage (and parts store!) I get a new fuel filter (the one that was in it was pretty cruddy) - the car fires up and runs great - I drive it all over town - about a half hour, get home shut it off - go inside - clean up a bit - come back out to restart it - and back to square one - its running rough again (Blah). I'm pretty frustrated at this point and I'm beginning to think I'm going to need to drop the tank (Yuck!) and put a new fuel pump in it - though when I turn the ignition on it seems like the pump is priming. (the only good point to all this is I know the engine will be all freshened up when I'm done - just need to change the water pump and alternator - LoL) I was wondering if possibly I have a bad fuel injector? Not enough fuel pressure? Or even one of those lovely computerized sensors out? What do you guys think? What should my next move be here? I would appreciate ANY feed back at this point!

Thanks!
Wildflower

 

Welcome aboard thirdgen.org.

Don't guess about the fuel pump. Get a fuel pressure gauge. About $40. You won't regret it.

Black plugs means they aren't firing properly or those cylinders are getting too much fuel. Injectors can leak from crud getting into them, so some sort of fuel additive may help. It may also loosen up a bunch of crud in your tank, so be prepared to change the filter again, and possibly drop the tank to replace the pick-up sock and/or fuel pump.

 

If the car sat for 3 years and you had a "cruddy" fuel filter I am not quite sure that a fuel additive is going to do the trick There is a good chance that the "gunk" that was in your fuel system clogged some of the injectors. You might just want to have them professionally cleaned and tested.

 

Thanks guys! I'm taking it up today to have a friend check the fuel pressure on it. I'll keep you posted on the outcome!

 

Turns out it was the injectors. Ordered a new set from summit racing, they just arrived this morning - keep your fingers crossed for me!

 

I would pull the new filter and replace again with another new one before you try starting it with the new injectors. You could always leave the filter off and let the pump prime into a glass jar to see if its still pumping crudd out. Most likely your tank has a bit of varnish inside and is getting pumped into your filter.

 

Great idea - thanks! I did buy a couple extra filters, but I didn't think about letting it prime in a glass jar first. I'll give it a try!

 

Final result - it was definitely the injectors! I changed them out last night and now she purrs like a kitten. I've been driving her all day with no hint of the past issue! Hope this helps some other's out there with the same issues - it seems this is a very common problem with the engines from this year.