Need help...engine dies when throttled up

Hi all. I recently purchased a 1994 18' Pro Craft w/175 hp Merc. black max that threw a bearing an hour after I bought it. The previous owner was a Mercury tech for Oconee marine and agreed to rebuild the engine for the cost of parts. Unfortunately he had to use a 150 block. Fast forward 2 months and I get the boat back. Idles fine, but the charging system doesn't work and as soon as you give it any real throttle, it dies. Once in a great while it'll plane up, but 95% of the time, it dies as soon as you give it gas. Had the carbs rebuilt and no problems. Fuel pump is ok. What could possibly cause this? The guy who rebuilt it skipped town and the only thing he told me is that I had to replace the 25 pitch ss prop with a 21 or 22 because of the hp drop. Could that possibly be the problem? If not, any ideas?

Thanks in advance!

P.S-The

Re: Need help...engine dies when throttled up

Welcome to IBOATS! You might check for some loose or corroded wiring first. One of the pro's will have more for you.

Re: Need help...engine dies when throttled up

Thanks. I switched props and it seems to work from what I could tell by running it in a big garbage can Could a prop possibly cause a boat not to run?

Windykid said:

Welcome to IBOATS! You might check for some loose or corroded wiring first. One of the pro's will have more for you.

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Re: Need help...engine dies when throttled up

You might try opening up the idle adjustment screws 1/8 turn (counterclockwise). You may be running a tad too lean causing the hesitation upon acceleration. When accelerating push the chock (key) switch in and hold it. If the problem is cured you are most probably running too lean! Good luck. I have been fighting this same problem on a 200 hp carb'd Merc for two years.

Re: Need help...engine dies when throttled up

Thanks for the response. I've had it into the shop but the guy working on it seemed semi-incompetent. He said it'd accelerate fine if he sprayed gas directly into the carbs, so I guess it's running lean, but apparently he didn't know what to do about that as he gave the boat back to me with nothing fixed, yet charged me $250. I'll try the choke and see if that helps it go. I'll try the idle screw too. ANyone have any ideas on the charging system? The rpm gauge went out at the same time if that helps. I've replaced the stator and the rectifier with no luck.

Thanks!

kiksav said:

You might try opening up the idle adjustment screws 1/8 turn (counterclockwise). You may be running a tad too lean causing the hesitation upon acceleration. When accelerating push the chock (key) switch in and hold it. If the problem is cured you are most probably running too lean! Good luck. I have been fighting this same problem on a 200 hp carb'd Merc for two years.

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