1994 Chevy Van Inconsistent spark

FERGIE342

MEMBER
1994 CHEVROLET VAN
V8
2WD
AUTOMATIC
241,000 MILES

The G30 I just bought (350 w/100k since rbld) makes almost no power. I got passed by a loaded schoolbus off the line this morning, and I'm getting single-digit mpg. I set the timing, replaced filters and bad vacuum lines and read the plugs; they're dry, but a dark rust color in most cyls. I went around the distributor with the timing light and found the aft 4 leads (cyl #7-2-1-8) indicated inconsistent sparks while the others produced a smooth strobe. Changing the cap and rotor had no effect. Is this a camshaft position sensor issue, or something else?

And speaking of timing, the VECI sticker calls for 0-BTC. Does that sound right?

VIN: 1GCHG39K1RF106794

Update: Replaced pick-up coil and ignition module and still have the same problem. In fact, maybe I didn't catch it before, but it seems that all cylinders are skipping. What else would cause this?

1 Reply

2CARPRO JACK

MECHANIC
11,533 POSTS

That timing setting sounds right. That engine ( K ) is aTBI unit, they are very solid. Sounds like you may have a module/pick-up coil going bad in the distributor.I would replace both at that mileage, they are both known to act odd at high mileage and fail. That engine doesnt have a cam or crank sensor so the pick-up coil and ignition module are it, much simpler than the newer ones