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First MPI Motor

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Old 10-04-2009, 09:17 PM
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Default First MPI Motor

OK...Ive always had carb motors and I just bought a 1996 252 Baja with an 05 7.4 MPI in it. Is it suppose to sound like its got a bad vacume leak every time you hit the throttle? Ive been told its the injection and they all do it. Sounds like hell and is there anyway to make it less noticeable...like shut it up.

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Old 10-05-2009, 02:30 PM
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my '99 502's have done this since new
Actually more pronounced once I installed the K&N filters
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Old 10-05-2009, 08:41 PM
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I guess I just have to live with it then .....or kick up the sub woofer It has the stock filter and I was going to put a K&N on it...so its going to get worse?
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Old 10-05-2009, 11:58 PM
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Originally Posted by [email protected] View Post
Sounds like hell and is there anyway to make it less noticeable...like shut it up.

signed "ole school"
Dry exhaust will take care of that

I just took out a customers 22 Donzi ZX for some prop testing after doing some work to it and it has the same noise. Your right it does sound like hell but it is a great setup though.
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Old 10-06-2009, 12:03 AM
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Mine sounds like it's starving for more air, it's just weird!
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Old 10-06-2009, 08:25 AM
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Sounds like an unsilenced air cleaner/spark arrestor. You guys must have really quiet exhaust systems. My EFI engines hiss when they are cold, or in gear at idle and the IAC's kick in, but not once I come off of idle. I have Holley injection and Gaffrig spark arrestors.
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Old 10-07-2009, 05:06 PM
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Sounds like an unsilenced air cleaner/spark arrestor. You guys must have really quiet exhaust systems. My EFI engines hiss when they are cold, or in gear at idle and the IAC's kick in, but not once I come off of idle. I have Holley injection and Gaffrig spark arrestors.
factory thru hull wet exhaust from baja. The swim platform hangs over a lot so its not as loud inside as it is outside. What are the benifits of this setup over carbs? Does a K&N help any? It appears to have the stock flame arrestor on it. Just sold my Scarab SCS and bought this boat last weekend. (need more room but really miss the power)
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Old 10-07-2009, 08:24 PM
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Default mpi

i am not too impressed w/merc,s early fuel injection.i had a 94mpi,502mag.after throwing alot of $$,and a new engine,i went back to a carb set-up.cheaper,simple,and best of all,i can work on it.it works for me.i did not see any diffrence in consumption.my advice on efi,is find a guy that is exprenced w,efi and performance boats and do not try to build up your motor.dont change anything.even the airbreather .just my 2cents.good luck
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