Thunderbolt IV Problem
#21
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does that use the delco EST dist ? if so, the shaft can go bad and create running issues that will drive you up a wall...ask me how I know !!!! local chevy dealer here stocks several shafts !
#22
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The TB-IV uses a Merc-spec distributor; it's not a Delco EST. I checked everything... no play in the distributor. The gear is new (and properly pinned).That was one of the first things I went after,
#23
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I was fighting this issue on a Stingray Maxim 222ss with an older 454 w/ Thunderbolt last week but haven't nailed it down yet. We finally got her to fire up and run with what sounded like a dead miss which cleared on its own briefly, then it would idle for a little bit and shut off. It would do it at High Idle (~1000 RPM) and normal idle. I was at the helm while my friend was in the engine bay and he thought I was turning the key off. Initial inspection showed the bowls were not filling but we didn't get much further than that. The boat was in bad shape when we snagged it last week in Delaware so we decided to do a full tune up anyway (Plugs, wires, cap, rotor, coil, belts, manifolds, risers, water pump, carb rebuild). We pulled the carb last week and rebuilt it over the weekend. I am supposed to go over there tonight to throw it back on with the new manifolds that are arriving today. I will let you know what I find unless you find your solution soon. Have you been able to check the timing while it is running?
#25
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Success!
I made sure the harness plug was solid and tight, replaced the coil, and changed the plug wires (had a bad connector in one so I swapped them all). I got her fired up, no real issues. She was a little rough at first, but smoothed out well once she got warned up. So ether the harness plug was giving us a bad connection, or the coil was breaking down once warned up. I'll take it!
I still have some issues with surging idle, but that's for another thread.
Thanks for all the help and suggestions!
I made sure the harness plug was solid and tight, replaced the coil, and changed the plug wires (had a bad connector in one so I swapped them all). I got her fired up, no real issues. She was a little rough at first, but smoothed out well once she got warned up. So ether the harness plug was giving us a bad connection, or the coil was breaking down once warned up. I'll take it!
I still have some issues with surging idle, but that's for another thread.
Thanks for all the help and suggestions!