- Joined
- Aug 3, 2010
- Posts
- 31,961
- Reaction score
- 32,864
- Location
- Usually not in Ohio
- First Name
- Andy
- Truck Year
- '77, '78, '79, '84, '88
- Truck Model
- K5 thru K30
- Engine Size
- 350-454
'84 C10, stock 305, headers, Holley 650 (couple years old), Mallory coil (old), recent tune up with good parts (not cheap junk).
There were tiny hints of things to come for the past couple days, but for the most part the trouble all started this evening. The truck was hiccuping and stumbling real bad intermittently while leaning into the throttle while driving down the road. But giving it a little more throttle smoothed it out. It idled just fine a reved normal while in park. If I mashed it off the line everything was normal. Then everything went to hell in a handbasket. It still idles fine, but light throttle it bucks and hiccups something fierce. It's really hard to drive at all. Heavy throttle still smooths it out, but power is certainly lacking.
The weird thing is, when it's bucking and acting up, the tach needle goes nuts. Even at speed. The tach will instantly drop to zero for a split second, then come back to life right as there's a nice healthy backfire out the exhaust. Because of this I'm thinking a bad ignition module. Or a possible bad pickup coil. I'm really no expert on the HEI stuff and what exactly makes it tick. Anyone have any ideas?
There were tiny hints of things to come for the past couple days, but for the most part the trouble all started this evening. The truck was hiccuping and stumbling real bad intermittently while leaning into the throttle while driving down the road. But giving it a little more throttle smoothed it out. It idled just fine a reved normal while in park. If I mashed it off the line everything was normal. Then everything went to hell in a handbasket. It still idles fine, but light throttle it bucks and hiccups something fierce. It's really hard to drive at all. Heavy throttle still smooths it out, but power is certainly lacking.
The weird thing is, when it's bucking and acting up, the tach needle goes nuts. Even at speed. The tach will instantly drop to zero for a split second, then come back to life right as there's a nice healthy backfire out the exhaust. Because of this I'm thinking a bad ignition module. Or a possible bad pickup coil. I'm really no expert on the HEI stuff and what exactly makes it tick. Anyone have any ideas?
