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I'm No Expert
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Discussion Starter #1
My buddy has a 22ft advantage with a Merc 454 Bravo 1 in it. This weekend he said that at high rpm the boat felt like it was stuttering or starving for gas. He said it would also hiccup when jumping on the throttle. He said at low speeds it seamed ok but he didnt drive it very long after this started just enough to get back on the trailer fearing that he might damange the motor. I was thinking fuel filter could be clogged or maybe some water in the gas. THe boats stored out at the river so i'm looking for as many possibilitys or things to check/look for so when i get out there i can help him diagnose it.
 

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It's what we do
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What year? Carb or FI? Mag or 7.4? How long since he ran it last? How long since it was serviced, fuel filter, etc.?
 

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I'm No Expert
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3,139 Posts
Discussion Starter #5
What year? Carb or FI? Mag or 7.4? How long since he ran it last? How long since it was serviced, fuel filter, etc.?
He just bought it, ran it a couple weekends. The guy before him i guess had it serviced. The engine area looks clean, it runs well and smooth, starts right up. It's the 7.4, he ran it two weeks before this problem started, fuel filter he said looks new but that doesn't mean anything.
 

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You still did not answer if carb or FI.
If carb, go thru checks like if your carb'd motor. Compression, fuel psi, plugs, cap, rotor, wires , charging, battery, stuck/sticking choke, etc.

If FI check same things but also get a Rhinda scan tool/program or similar (like Mefiburn) and check things out. System voltage is especially critical on EFI boats. Under/overcharging or a plate problem in battery can make it act weird in specific spots.

Since it was just 'serviced' be suspect of loose or improperly routed ignition wires, and/or anything that was probably touched.

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I know your trying to help, but you gave no specific information and thus no way to really help other than remind you what generics to start checking.

After some actual diagnostics and if you don't find the problem, report back with what you looked at, what that showed you, and etc.
 

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Registered
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Check all the vacuum lines and make sure that they got back to the right place.
Example, didn't have time to chase down a distributor problem in my tow vehicle. Took it in for service and they found a broke wire going to a sensor. Got the truck back and it would run fine ant idle, but sputter when pulling a load. When they put the vac lines back they had connected it to a factory plugged bung and not the correct one. Moved the vac line and bingo, ran fine.
Wish I could of got some money back on that deal :mad:
 

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Engine junkie
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142 Posts
"T" in and check fuel pressure to the carb while under way, also check for a fuel inlet filter at carb, that could be clogged too. I suspect a bad fuel pump due to the fact that this seems to be an "all of the sudden" thing.
If the boat sat for some time a soft collapsed tank to pump fuel line could also be a culprit here. :)bulb
Also as Itsahobby said check all vacuum lines and caps too. A small backfire could have blown a cap off.
 
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