Cutting out at high throttle on carbureted 454
07-31-2015, 07:37 PM
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Cutting out at high throttle on carbureted 454
Ok here's a tough one for all u master mechanics out there. The 454 in this 22z is cutting out at about 3800 rpm... Right when it really wants to go fast. It's not misfiring because it has a rythm to it high rpm low rpm high rpm low rpm... And when it drops it looses about 500 rpm then comes right back to immediately fall again... I thought timing may of been off but that's set at 8 degrees like the manufacturer says... A buddy of mine that's had race boats his whole life says it's the inline check valve in the fuel tank sticking he says every time he got a new boat he had them take that out from my understanding that's illegal but that's aside the point... The boats been sitting for a couple years now and the fuel filter was just replaced last week... Is it even fuel? I wanted to leave it to you guys for some advise... Has anyone ever had this issue and if so what did you do to fix it? Thanks for the help
08-01-2015, 02:50 PM
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Im having the same problem on my Port Mercury Bulldog 500 today.
As soon as Im about to get on plane my Port rpm drops to zero. It revs fine without being in gear but when under load it drops rpm after about 5 seconds of running up. Starts right back up idles fine doesnt misfire while bringing the power up.
As soon as Im about to get on plane my Port rpm drops to zero. It revs fine without being in gear but when under load it drops rpm after about 5 seconds of running up. Starts right back up idles fine doesnt misfire while bringing the power up.
08-03-2015, 10:30 AM
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Water in the fuel? That's interesting the only filter I see in there is the fuel filter then it goes to the fuel pump on the side of the motor (cam driven) I'll see if I can find the fuel water separator that would make since
08-03-2015, 07:41 PM
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They look like oil filters and they spin on.
I ran my boat the other day and when I brought the power up the port motor with just go to zero. I took the filter off and replaced it...$13 and it runs perfect now. Ran it all weekend. You should really see if you have one and if so replace it. (cheap to do) and then test it. At least you will know that its something else if it doens't work and it wont cost much to try it. Takes about 3 minutes to replace it with a filter wrench.
