First MPI Motor
10-04-2009, 08:17 PM
#1
Registered
Thread Starter
Join Date: Sep 2008
Location: Middleburg, Fla
Posts: 44
Likes: 0
Received 0 Likes
on
0 Posts
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.
signed "ole school"
signed "ole school"
10-05-2009, 01:30 PM
#2
Charter Member#157
Charter Member
Join Date: Oct 2000
Location: Minneapolis, Mn, Usa
Posts: 1,859
Likes: 0
Received 3 Likes
on
3 Posts
my '99 502's have done this since new
Actually more pronounced once I installed the K&N filters
Actually more pronounced once I installed the K&N filters
__________________
This Cat is trying to keep up with the Big Dogs
This Cat is trying to keep up with the Big Dogs
10-05-2009, 07:41 PM
#3
Registered
Thread Starter
Join Date: Sep 2008
Location: Middleburg, Fla
Posts: 44
Likes: 0
Received 0 Likes
on
0 Posts
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?
It has the stock filter and I was going to put a K&N on it...so its going to get worse?
10-05-2009, 10:58 PM
#4
VIP Member
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.
__________________
Throttles- Cleveland Construction 377 Talon
08 OPA Class 1 National Champion
08 Class 1 Geico Triple Crown Champion
08 OPA High Points Champion
10 OPA Class 1 National Champion ( happy now Ed! )
Throttles- Cleveland Construction 377 Talon
08 OPA Class 1 National Champion
08 Class 1 Geico Triple Crown Champion
08 OPA High Points Champion
10 OPA Class 1 National Champion ( happy now Ed! )
10-06-2009, 07:25 AM
#6
Diamond Member #001
Charter Member
iTrader: (2)
Join Date: Oct 2000
Location: Coastal North Carolina
Posts: 4,808
Likes: 0
Received 5 Likes
on
4 Posts
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.
__________________
Retired! Boating full-time now.
Retired! Boating full-time now.
10-07-2009, 04:06 PM
#7
Registered
Thread Starter
Join Date: Sep 2008
Location: Middleburg, Fla
Posts: 44
Likes: 0
Received 0 Likes
on
0 Posts
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)
10-07-2009, 07:24 PM
#8
Registered User
Gold Member
Join Date: Apr 2007
Location: prince george,va
Posts: 1,474
Likes: 0
Received 0 Likes
on
0 Posts
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
