Go Back  Offshoreonly.com > Technical > General Q & A
7.4 MPI very sluggish >

7.4 MPI very sluggish

Notices

7.4 MPI very sluggish

Thread Tools
 
Old 08-17-2010, 09:52 AM
  #11  
VIP Member
VIP Member
Thread Starter
 
Ebay Ed's Avatar
 
Join Date: Nov 2009
Location: Ohio
Posts: 1,520
Likes: 0
Received 1 Like on 1 Post
Default

Paul i know why you dont like the injection is because of the electronics and the water but my engine compartment / bilge doesnt see any more water than my truck does and it has way more electronics than my boat does with none of the issues that i am having now with my boat
__________________
www.bajaboatowners.com
Ebay Ed is offline  
Old 08-17-2010, 10:23 AM
  #12  
Registered
iTrader: (5)
 
Join Date: Mar 2010
Location: morehead n.c
Posts: 1,826
Likes: 0
Received 6 Likes on 3 Posts
Default

my boat didnt start missing till this weekend , but its been slugish for a long time its a 226 baja 23' long i have been changing props like there going out of style lol steal slow only 42mph @4000rpms with a 23p 3 blade giveing it all she has! And steal can't hit the rev lim/. how fast should it go about??? and i was told most sbc have 55-60pai for fuel presure
ridefast77 is offline  
Old 08-17-2010, 10:46 AM
  #13  
Registered
iTrader: (1)
 
Join Date: Aug 2004
Location: Fort Worth, Texas
Posts: 1,075
Received 10 Likes on 6 Posts
Default

Originally Posted by Ebay Ed
Paul i know why you dont like the injection is because of the electronics and the water but my engine compartment / bilge doesnt see any more water than my truck does and it has way more electronics than my boat does with none of the issues that i am having now with my boat
I understand that, but also GM, Ford and Chrysler has alot more money to put into their development programs than Mercruiser will ever have. Doesnt matter if water is inside the bilge or not. You said there is none in yours, so you have proven my case...electronics and boats/water do NOT play well together. Look on any boat forum and it is endless with issues related to EFI/MPI or some sort of an electronic issue. All my friends out here that have dumped the EFI/MPI and went to carbs have no more issues and I have found that people with carb issues mess with them when they think they know what they are doing, but in reality...they dont know what they are doing resulting in screwing them up. With a carb, there isnt a whole lot of electronic crap and if your motor doesnt run right...it is either spark of gas...no sensor this or that or some BS guardian mode. Now someone is saying to check the screens on the injectors...no fuel filter?? My best bud had all sorts of off & on issues with his MPI shortly after he bought it. Now there is a carb on it and all he has done the past 2-1/2 years is change the oil, plugs and sea pump inpeller and he boats everyday "without" any issues. All up to you...I feel for ya, but you have to decide...you want to boat or sit on the trailer.

Last edited by pslonaker; 08-17-2010 at 10:50 AM.
pslonaker is offline  
Old 08-17-2010, 10:49 AM
  #14  
Registered
iTrader: (1)
 
Join Date: Aug 2004
Location: Fort Worth, Texas
Posts: 1,075
Received 10 Likes on 6 Posts
Default

Originally Posted by ridefast77
my boat didnt start missing till this weekend , but its been slugish for a long time its a 226 baja 23' long i have been changing props like there going out of style lol steal slow only 42mph @4000rpms with a 23p 3 blade giveing it all she has! And steal can't hit the rev lim/. how fast should it go about??? and i was told most sbc have 55-60pai for fuel presure
You might have some other issues as well. I would start with a compression check on the motor. But, if you want to see if it will turn anymore RPM...put a 19 inch prop on it and go run it to see what happens. If it is the same as with the 23 inch...then you DO have issues.
pslonaker is offline  
Old 08-17-2010, 11:26 AM
  #15  
VIP Member
VIP Member
Thread Starter
 
Ebay Ed's Avatar
 
Join Date: Nov 2009
Location: Ohio
Posts: 1,520
Likes: 0
Received 1 Like on 1 Post
Default

i really think that both of us are having the same problem and it is a fuel pump issue since i have already changed all of the electronics from my old engine to the replacement and nothing has made a difference and it just keeps getting slower which could be from the fuel pump getting worse
__________________
www.bajaboatowners.com
Ebay Ed is offline  
Old 08-17-2010, 11:27 AM
  #16  
Registered
iTrader: (5)
 
Join Date: Mar 2010
Location: morehead n.c
Posts: 1,826
Likes: 0
Received 6 Likes on 3 Posts
Default

Originally Posted by PSlonaker
You might have some other issues as well. I would start with a compression check on the motor. But, if you want to see if it will turn anymore RPM...put a 19 inch prop on it and go run it to see what happens. If it is the same as with the 23 inch...then you DO have issues.
i did that, i stated with a 23p 3blade then a 21p 4 blade then 19p 4blade then just cause i had one a 23p 4blabe then back to the 23p 3blade all ran like ass the fastest i could get it to go on gps was 42mph i checked the compression about 2 mouths ago and had 127 in all 8 i thought that was good?
ridefast77 is offline  
Old 08-17-2010, 12:13 PM
  #17  
Registered
iTrader: (1)
 
Join Date: Aug 2004
Location: Fort Worth, Texas
Posts: 1,075
Received 10 Likes on 6 Posts
Default

Originally Posted by Ebay Ed
i really think that both of us are having the same problem and it is a fuel pump issue since i have already changed all of the electronics from my old engine to the replacement and nothing has made a difference and it just keeps getting slower which could be from the fuel pump getting worse
Could be a fuel pump...pull a couple of plugs and see what they look like.
pslonaker is offline  
Old 08-17-2010, 12:14 PM
  #18  
Registered
iTrader: (1)
 
Join Date: Aug 2004
Location: Fort Worth, Texas
Posts: 1,075
Received 10 Likes on 6 Posts
Default

Originally Posted by ridefast77
i did that, i stated with a 23p 3blade then a 21p 4 blade then 19p 4blade then just cause i had one a 23p 4blabe then back to the 23p 3blade all ran like ass the fastest i could get it to go on gps was 42mph i checked the compression about 2 mouths ago and had 127 in all 8 i thought that was good?
127 is sorta low...160's would be alot better.
pslonaker is offline  
Old 08-17-2010, 01:23 PM
  #19  
Registered
iTrader: (5)
 
Join Date: Mar 2010
Location: morehead n.c
Posts: 1,826
Likes: 0
Received 6 Likes on 3 Posts
Default 7.4L (454) MPI Fuel Pressure

Found actual fuel pressure range to be 37 - 43 PSI 35 PSI @ idle and 33 PSI @ 2000 RPM (no load). Tech support says this is normal and spring pressure in the pumps override the electrical pump under load and pressure comes up 4-5 PSI.
ridefast77 is offline  
Old 08-17-2010, 01:37 PM
  #20  
VIP Member
VIP Member
Thread Starter
 
Ebay Ed's Avatar
 
Join Date: Nov 2009
Location: Ohio
Posts: 1,520
Likes: 0
Received 1 Like on 1 Post
Default

i really think we both have fuel pump problems
__________________
www.bajaboatowners.com
Ebay Ed is offline  


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.