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496 Stroker...irratic rpm..stalling

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496 Stroker...irratic rpm..stalling

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Old 10-10-2015, 01:50 PM
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Default 496 Stroker...irratic rpm..stalling

Hello everyone. I am stumped on the issue that I am having. I recently had a 496 stroker built. We installed it and it ran great for about 200 miles. Like an idiot, it ran out of gas on the gulf and we had sea-town bring us 6 gallons to get home (we took a few heavy waves in the engine bay while the hatch was open (Baja 232).

Sea tow brought us the gas and it started right up. We drove about 4 miles home, flushed the engine and the boat sat for a while. Next time out, the boat won't go over 3k rpms after the 1st minute out. It jumps between 2500-3000 rpm..almost in rhythm when I try to give it throttle. At first I thought I noticed it shutting down even more when the boat rocked or I hit a wave..however, It wouldn't go above 3k.

I noticed the volt meter was reading low and the tach going to 0 while underway when I press a button or move the trim.

Thinking that I had some bad connections, I focused on a fuel issue with weird RPM thing. I took the carb off, opened it up.. Cleaned it out (rebuilt 20 hours ago). Checked all the jets..compressed air and carb cleaner. I assumed that the seatow gas left in the tank (Florida heat) turned to water.

Today I hooked it up on a remote tank and the same thing happened. It screamed to 4k..then got less...less.. and by the end of a 3 minute drive it would only be happy at 2900 rpm..or it would start cutting out until I backed off on throttle. By the end of the quick drive..the volt gauge was at 9..and the tach was doing the same thing when I used anything with power.

I obviously have a bad alternator (10 volts when running..batteries, switch, and alternator itself). Can a bad alternator cause the low weird RPM thing I'm seeing? Could the Thunderbolt IV be bad with the sea water splash that hit us?

I am out of ideas. I just spent $9k in the last 3 months and know this boat pretty well. Its a very odd problem. It was running very very well before the out of gas scenario.

Thanks again,

Joe

Baja 232
496 Carb Stroker
BajaBossJD is offline  
Old 10-10-2015, 01:56 PM
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Get your voltage issue fixed first....you need to have a steady voltage to troubleshoot the engine issue. It sounds like an ignition issue to me but I would make sure my charging system was correct first.
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Old 10-13-2015, 12:18 PM
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Start with electrical as stated above, that wave over the back could've toasted an alternator or something else. As for the RPM's dying, I had a similar issue with a vac sec carb, it ended up being a stuck float.
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