Go Back  Offshoreonly.com > Technical > General Q & A
Merc 496 HO losing RPM >

Merc 496 HO losing RPM

Notices

Merc 496 HO losing RPM

Old 05-17-2020, 11:21 AM
  #1  
Registered
Thread Starter
 
Join Date: Aug 2018
Location: Saugatuck, Michigan
Posts: 22
Likes: 0
Received 0 Likes on 0 Posts
Default Merc 496 HO losing RPM

2003 Baja Outlaw
twin 496 HO's
Boat ran great all day.....temp were perfect, oil psi good, volts good.
Then trying to get on plane, stb motor would get to 4000rpms, alarm would go off and rpms would drop steady back to 1000. During this gauge read outs were normal.
Has anyone had a simmular problem ?
Thank you
Bart A
bacino1960 is offline  
Old 05-17-2020, 11:24 AM
  #2  
Registered
 
Join Date: Oct 2012
Posts: 1,353
Received 11 Likes on 6 Posts
Default

Yes could be a number of issues. You will need to scan pcm.
underpsi68 is offline  
Old 05-17-2020, 11:51 AM
  #3  
Registered
Thread Starter
 
Join Date: Aug 2018
Location: Saugatuck, Michigan
Posts: 22
Likes: 0
Received 0 Likes on 0 Posts
Default

Thank you
planning to set that up for next week
purchasing scan tool
putting in the eng info....
Rinda Scanners
Tech mate Pro 94706. ?
bacino1960 is offline  
Old 05-17-2020, 12:13 PM
  #4  
BUP
Registered
iTrader: (9)
 
Join Date: Jul 2011
Location: Ft. Worth TX
Posts: 9,591
Likes: 0
Received 19 Likes on 17 Posts
Default

if you need the correct scan tool and the correct adaptor let me know I can direct you.
BUP is offline  
Old 05-17-2020, 12:27 PM
  #5  
Registered
Thread Starter
 
Join Date: Aug 2018
Location: Saugatuck, Michigan
Posts: 22
Likes: 0
Received 0 Likes on 0 Posts
Default Scan tool

Yes please
boat is a 2003 Baja
Twin 496 HO
let me know what other info you may need
Bart
bacino1960 is offline  
Old 05-17-2020, 05:44 PM
  #6  
BUP
Registered
iTrader: (9)
 
Join Date: Jul 2011
Location: Ft. Worth TX
Posts: 9,591
Likes: 0
Received 19 Likes on 17 Posts
Default

great I can direct you where to and what is needed -- only thing needed your contact info. Thanks.
BUP is offline  
Old 05-17-2020, 08:03 PM
  #7  
Registered
Thread Starter
 
Join Date: Aug 2018
Location: Saugatuck, Michigan
Posts: 22
Likes: 0
Received 0 Likes on 0 Posts
Default Scan tool

Bart
734 578 2815
bacino1960 is offline  
Old 05-18-2020, 07:55 AM
  #8  
Registered
 
Join Date: Jul 2011
Location: Clearwater, FL
Posts: 4,797
Received 7 Likes on 6 Posts
Default

As some said a scan will be needed. That said I had the same issue and the scanner was showing all ok.

it wasn't until we chose to single out and watch the water PSI that we found a bad pressure switch that would stop reading water PSI at speed and was causing the issue. Cheap part, long and drawn out testing to repair.
Nate5.0 is offline  
Old 05-18-2020, 08:46 AM
  #9  
Registered
Thread Starter
 
Join Date: Aug 2018
Location: Saugatuck, Michigan
Posts: 22
Likes: 0
Received 0 Likes on 0 Posts
Default Baja

Thanks Nate
is it the sensor in the water pump housing ?
bacino1960 is offline  
Old 05-18-2020, 08:53 AM
  #10  
Registered
Thread Starter
 
Join Date: Aug 2018
Location: Saugatuck, Michigan
Posts: 22
Likes: 0
Received 0 Likes on 0 Posts
Default Baja

I was also told my temp readings are too cool !
I find that hard to believe.
Last season I was running 185 to 190+
I pulled heat exchangers and many were blocked.
Cleaned out all tubes....dropped temps to around 170.
Over the winter I rebuilt the Hayden water pumps, new wear plates and impellers.
Temps now 160-170
B
bacino1960 is offline  

OSO Sponsor
OSO Advertiser
OSO Advertiser

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information

Copyright © 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.

OSO Advertiser