Recently I purchased a 94 vette with 63,000 miles on it. After a couple of weeks I started having a sputtering problem when I would drive it for more than thirty minutes. The car would run great for the first thirty minutes and then cut off, or not let me get higher than 3 RPMs while sputtering, almost like it was flooding. With no hesitation, I took the car to the local Chevy dealer thinking that it was bad fuel. The dealer drained the tank, drained the trans, cleaned the injectors, and checked the fuel filter for pressure. The dealer stated that the fuel pressure was around 20-psi and it should be around 60-psi. So we changed the fuel filter and got the 60-psi desired. Thirty minutes into my drive the next day the car did the exact same thing. I only use high-test fuel, so I've crossed off fuel as the problem. I have no problem with over heating or smoking. Could it possibly be a vacuum leak? The cruise control does not work and I saw on another post it could be a sign of a vacuum leak. Any ideas would be greatly appreciated.

 

It is sounding to me like a bad opti...

also, check the coil/wires/plugs.

 

Does sound like your distributor is dying. It is called an OptiSpark distributor and it is mounted on the front of the engine block beneath the water pump. I am surprised the dealer shop did not suspect this.

 

Everyone wants to jump on the "opti bandwagon"......I think he has a fuel issue...once again a bad OPTI will backfire...it messes up the psark delivery...then Bam the fuel that should ormally be delivered it all of a sudden ignited.If he has a fule issue it would stumble and act flooded...well actually the opposite of flooded starved..

1.SES light come on?....if yes...what codes?
2..Fuel level?
3..Are the fans on constantly when it does this act?
4...When it did it again did you recheck the fuel pressure?......I am thinkin 60 psi is real high?...maybe mid to upper 40's should be good.
5....Do you're vents work properly when selected?..as in a/c vents.??

 

it sounds ALOT like the opti-spark, mine did the same thing about 3 months after I bought it. had new opti-spark,plug wires, spark plugs ignition coil, new water pump(being the old one had to come off). after that it runs like new.

 

Now can I say...it... OPTI .....OPTI....OPTI

OOOOP--TEEEEEE!!!!! OPTI ......OPTI!!!

 

Since there has been a recent run on dying Opti's.. It has to be something in the air.

 

If it doesnt want to turn revs over 3K it could be clogged catalytic converters. Mine smelled hot after running if for a while. Probably not but worth a check.

 

Check for codes if any then first thing I would check is your coil wire, check it visually for cracks, abrasion, etc. Even if it looks perfect (mine did) try a new one. 1st issure I had with my Vette, thought it was the opti, learned the hardway on that one had to be towed eventually to a dealer. It was still under warranty but since it wasn;t a covered part I ate the tow! If not that, then check to make sure MAF isn't blocked somehow by something, I'm not quite sure how, I am thinking a leaf blew in somehow when I had the air intake tube off working on something?!? But my car was running Great one stop light then like crap and would barely make it home, sure enough a leaf was sucked into it. These are the easy things first. Next coil itself, plugwires, ignition module. If its not that If you have a fuel pressure gauge with hose on it you can tape that to your windshield so you can read it and go for a drive and when it stumples watch your pressure.
If it drops might be a fuel pump issue. If those checks pass I'm afraid to say its most likely your opti.

I got real good at these checks after my head cam swap and was eating an opti every month, The 1st couple of times I wanted it to be something else so I checked all these, the last few I just went straight for the opti. Thats why I LOVE the LTCC!!! Goodluck!

 

You might want to check for clogged cats. The easy check is to drive for that 30 minutes in the evening and take a look at the header and the pre cats and see if they are almost red hot.

 

Not saying that it's the issue, but 60psi IS to high. 41 lbs is the number I think, but research it a bit more. I have my '94 set to 37-39 depending on which high end pressure guage I use to make best power on the chassis dyno. See my post above on the mass air meter problem I just fixed, but don't let it throw you off. Let us know when you get it fixed and what it was. -Brian Nutter