Long story short, I bought my 1978 vette about 1 month ago, running great. I've had it to my mechanic and he can't figure it out, so my hope goes to all of you guru's as I am not that engine savvy myself!

Here is what happened and what has been done so far:
Recently the engine died while running, was rolling in to a parking spot so it was almost at idle. After that it refused to start - the starter runs strong, but didn't fire up. Mechanic replaced two parts, the ignition coil and a part that looks like flat three sided boomerang, 3-4 inches long and has two flat metal connectors at each side/edge. (been searching on how to post pictures, couldnt find it).

Now it started, but it ran REALLY poor, very little response on the throttle and a struggle get up to 50mph, barely drivable. My mechanic now replaced: sparkplugs(based on that they looked poor), distributor cap, distributor rotor and the wire set. It runs better, but far from as strong as it was. Delayed power on low RPM and high rpm winds the engine more than getting acceleration. Freeway speeds was a struggle and accelerating when at 65 was SLOW.

Hopefully my descriptions will make someone understand something hehe. My father is no mechanic but had a guess on the fuel filter?

Idle when cold is about 1400rpm instead of 1800 before it died. Idle when hot is about 900rpm instead of 500-600 before (and not as smooth at 900). I guess this could have been adjusted by my mechanic. Also after driving for 1hr, i had trouble starting the car again, engine fired up after pumping the accelerator, but died at idle again after revving. 10 minutes later I did the same thing and was able to drive away.

Any help would be MUCH appreciated!
Sebastian

 

You said your mechanic replaced the coil. Check to see if the polarity of the coil wires are correct. Been there and the engine will run but crappy if the wires are reversed.

 

I'd be checking for a vacuum line that came off or broke.

 

Ok sounds like you have HEI ignition..he replaced what's called the module..and the coil..so this car just decided to shut off and those two parts were replaced..did the car start after it died for you the first time or did you have to get it towed in to be worked on because it wouldn't restart..if it did start right back up how did it run..the guy fixin the car sounds like he has an idea of what goes on in these things so don't give up..one thing I would check would be the EGR valve..if the guy replaced all that tune up stuff it should run good..if that valve is sticking open just a little it will make the car run like poop..how does the car idle..if its rough then tap on the valve and see if the idle changes..if that doesn't apply then it may be time to play with the carb..there is a little fuel filter on the carb itself that may be dirty..just out of curiousity did you just fill up with gas..we have had a bunch of bad gas lately around here..cars haven't liked it to much..even had a station that put E85 in the E10 tank..man that was a mess..anyhow..I will wait to hear some answers then go from there.

 

Thanks for your replies, let me try to answer your questions Chromie69.

I had to have it towed to my mechanic when it did not start the first time. Actually waited to the morning after it stopped to try do start again after resting. same result, then towed. Originally the if the car was warm it idled at about 500-600rpm really smooth. Now it's about 900-1000rpm running a little rougher(making the car shake some), doesn't feel like the engine is dying, but def. not as solid/smooth as before. I feel like the engine doesn't sound as solid as before in general, but I'm not sure.

Gasoline only, been filling 91 until i read on the forum this weekend that 87 is fine. It's a L48. I went through more or less an entire tank of 91 going back and forth from San Diego to LA this weekend, put 87 for the first time and it seemed to on the way back it was a tiny bit better (lower rpm at 65mph), but i wouldn't swear by it. Thanks for the vote of confidence on my mechanic, I was starting to doubt him. Since I figured he messed something up making the car run differently after only a startup problem.

 

Hows the choke? If it doesn't open all the way: you'll run rich ( Hard to restart)and (#2)the secondaries will not open(Less power).

 

I would second the vacuum leak. My car started running horribly, shuddering and sometimes dying at idle, and it was a bad rubber gasket in the valve cover for the flame arrestor.

Sounds like your mechanic might have adjusted the carb so that the car wouldn't run rough or die at idle

 

Well I mentioned your tech knows something about these because its tough to find anyone who even knows what HEI is..it does sound like he adjusted the carb somehow after the parts were replaced...but he would have had to adjust the fast idle on the choke side and the base idle..he lowered one and raised the other..hmm makes the point of the choke sticking on some..the fast idle cam may be stuck up a notch and he adjusted that instead of popping it down to the idle screw..kinda tough to describe what I am talking about..I guess one thing you could do is remove the air cleaner with the engine cold..start it up by pumping the gas to the floor once and get it going..look at the carb and see if the choke is slightly open....now wait about five minutes..and tap the gas and see if the choke opens all the way..now on the drivers side of the carb is the base idle screw..make sure the linkage is touching that screw..it has a big spring going to it with cables on it..you can find it by hitting the gas and see what moves ..if it doesn't hit that screw then go to the other side..there is a round part on the carb..that is the choke spring housing..in front of that is the fast idle cam..see if you can push it towards the front of the car..to make it go down..you wont hurt anything in there but it should be easy to move..see if this does anything and we'll go from there.