Ok, I guess I’ll start with a little background.
Vehicle: 86 Chevy Pick-Up
Engine: 4.3L V6 with a 4 barrel carburetor (last year before fuel injection) carb rebuilt 2-1999
Camshaft is #2 at this site
installed 1-2000 by me. Engine has 245,000 miles on it, 170psi at all 6 cylinders, manifold vacuum is at 18-20”. I replaced the plugs, wires, cap, rotor, and coil recently. The ignition module was replace in 1997 after it stalled out and wouldn’t start.
I took it out for a drive on the highway and tached it up pretty high in 2nd gear. The next red traffic light I came to, the motor began to rumble at idle (in drive) as if I have a vacuum leak. There’s about a million vacuum lines all over this engine, but I could not find any leaks. It idled crappy for a little while, but when I got home, it seemed to have went away. The next morning, it started up as normal, but it would not stay running. It just would not idle, any rpm above idle was fine, but at idle it would rumble. I don’t hear any pinging or knocking, just would just shake the truck. After driving, for a little while the temp will come up to 210º, normally it’s lower at like 185°. I thought the problem might be the ESC (Electronic Spark Control module) because I’ve had to replace that in 1999 as well, but I disconnected it and jumped terminals A & C at the HEI side and it still had the same idle problem. So yesterday I began doing all the tests, I can get it to idle if I pump the gas and then start it, but if I hit the pedal to a higher rpm and let it down again, it’ll die. The carburetor is squirting fuel with nice streams, and after checking compression and vacuum, I took it for a spin, and this time, it would hardly move. I can get it to rev up in neutral, but when I use Drive or any other gear, the engine will not increase rpm.
So now the problem, has either gotten worse or more problems are showing up. Today I’ll be replacing the pick up coil in the distributor to check that off of this list of possibilities.
Oh here’s a funny thing: early on in the testing, while it was still able to rev up, I was able to pull all three spark wires on the passenger side and it would still run with little to no change in idle. And they were sparking fine, because I got shocked a few times.
Sorry this may have sounded real confusing, but I just tried to get as much info down as possible. Any ideas???