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No power above idle 2000 Chaparral 252 with 5.7 Mercruiser Bravo III

rallen8122

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I have a 2000 model Chaparral 252 with low hours on a 5.7 Mercruiser Bravo III that has run good till last year. Idles good but does not have enough power to get the boat up on plane. Had a strong fuel smell so had a mechanic go over everything, Running through all the checks the fuel smell did not reappear. Changed the module in the distributor, checked fuel pressure to the TBI and was good. Had a shop check out the MEFI 3 and found no problems. Tried another MEFI 3 just for good measure with no improvement. No water in the fuel. Stumped now...............any ideas????
 
Which ignition system.... I never get a third reliable season out of a Thunderbolt high energy distributor cap in a salt water environment... always change it on alternative seasons, if low hour seasons.... every year for high use seasons
 
Which ignition system.... I nTever get a third reliable season out of a Thunderbolt high energy distributor cap in a salt water environment... always change it on alternative seasons, if low hour seasons.... every year for high use seasons


The mechanic did change the cap. I'm in central Alabama on Lake Tuscaloosa so no saltwater.
 
did they check the fuel pressure out on the lake, with the engine under load, or just sitting at the dock?
 
don't remember what he said it was but he checked it both ways. The mechanic was concerned about not being able to fix it and had a competitor in Birmingham check it out. Same result - they couldn't fix it either and even went over it with Mercruiser techs. Amazing, its just a 350 chevy, with a throttle body injector, shouldn't be this hard.
 
don't remember what he said it was but he checked it both ways. The mechanic was concerned about not being able to fix it and had a competitor in Birmingham check it out. Same result - they couldn't fix it either and even went over it with Mercruiser techs. Amazing, its just a 350 chevy, with a throttle body injector, shouldn't be this hard.

Did you check the actual health of the engine? Compression test at minimum.
 
also replaced the MAP sensor and the fuel pressure sensor. Thought there might be some vacuum leaks so installed new intake manifold gaskets, checked hoses.
 
Plug a remote tank to the engine and retest. 190 seems a bit on the high side so recheck those numbers .Verify the plug firing order 1,8,4,3,6,5,7,2 clockwise
 
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