Go Back  Offshoreonly.com > Technical > General Q & A
700SCi defueling/guardian mode problem >

700SCi defueling/guardian mode problem

Notices

700SCi defueling/guardian mode problem

Old 08-22-2020, 04:10 PM
  #1  
Registered
Thread Starter
 
Join Date: Mar 2020
Posts: 14
Likes: 0
Received 0 Likes on 0 Posts
Default 700SCi defueling/guardian mode problem

I have a 2007 fountain lighting with the staggered 700SCi & #6 drive set up and have been having a problem for quite some time. The port side motor is good to go but the starboard side motor is basically cutting fuel to itself or in guardian mode when under load, in Forward, when it gets to around 1500ish and beyond. The tach, oil pressure and water pressure gauges are also going out of whack when this happens as well but theyíre reading perfect on my garmin/vessel view on the dash so I doubt itís any of those sensors. Both engines turn over, start up and idle perfect. In neutral when both engines rev up they both hit around 2800-3000rpm before the rev limiter on the computer beeps a few times and cuts them out. So why would the boat beep and cut fuel under load at the 1500ish rpm range and not till 3000ish rpm in neutral? What changes when the boat goes into gear? Why would the boat be in guardian mode and not throw any codes? (I had them scanned)

I just recently put brand new interstate cranking batteries in the boat and voltage is good, tps sensors are good, I replaced both iacís a few weeks ago so those are good. Pcms are good. Grounds to batteries and backs of engines are good. Wiring to alternator is good. Coolant level is good. Water pressure from the sea strainers is good. Engine temps are good. I have all new oil, oil filters, water separators, in line fuel filters, air filters as of 5 hours ago so those are good. Im running out of ideas here but Iím thinking itís a electrical wiring/ground issue.

Any insight is helpful. Thanks.
ImLate is offline  
Old 08-22-2020, 08:47 PM
  #2  
Charter Member # 55
Charter Member
 
Griff's Avatar
 
Join Date: Oct 2000
Location: Omaha
Posts: 18,378
Received 765 Likes on 375 Posts
Default

Need to check fuel pressure under load. Revving to 3000rpms in neutral does require the same amount of fuel as being run under a load.
Griff is offline  
Old 08-23-2020, 11:44 AM
  #3  
Registered
 
Join Date: Dec 2007
Location: Cary, IL
Posts: 168
Received 5 Likes on 3 Posts
Default

Maybe your starboard PCM thinks you are sill in neutral? Over speed doesn't set a fault, just sounds the alarm rev limiter. Connect a scanner and make sure the PCM sees that your starboard engine isn't showing that you are in neutral when you shift into forward.

It's odd that your gauges are going crazy so I'd also try disconnecting your AGI box and see if the problem goes away. They are notorious for failing and maybe it is messing with your tach signal and causing the PCM to activate the rev limiter. Your Garmin / VesselView signals are not routed through the AGI box, which could explain why they are working properly.

GF?
Got Freedom? is offline  
The following 3 users liked this post by Got Freedom?:
Griff (08-23-2020), SB (08-23-2020), VoodooRob (08-24-2020)
Old 08-24-2020, 08:02 AM
  #4  
Platinum Member
Platinum Member
 
VoodooRob's Avatar
 
Join Date: Jul 2011
Location: Cleveland Ohio
Posts: 1,981
Received 31 Likes on 15 Posts
Default

^^ Great suggestions, Also did you install Mercury brand IACs with the factory gasket? To throw this in the mix, you could have a PCM that needs repair.
VoodooRob is offline  
The following users liked this post:
BIGSLOW (08-25-2020)
Old 08-24-2020, 09:47 AM
  #5  
Registered
Thread Starter
 
Join Date: Mar 2020
Posts: 14
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by VoodooRob View Post
^^ Great suggestions, Also did you install Mercury brand IACs with the factory gasket? To throw this in the mix, you could have a PCM that needs repair.
Yes theyíre factory mercury IACís so the computers should be fine. I bought them at a local marina thatís a merc racing dealer. They werenít bad when I changed them, I just figured Iíd do it as PM as I didnít know the last time they were changed.
ImLate is offline  
Old 08-24-2020, 09:49 AM
  #6  
Registered
Thread Starter
 
Join Date: Mar 2020
Posts: 14
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by VoodooRob View Post
^^ Great suggestions, Also did you install Mercury brand IACs with the factory gasket? To throw this in the mix, you could have a PCM that needs repair.
Originally Posted by Got Freedom? View Post
Maybe your starboard PCM thinks you are sill in neutral? Over speed doesn't set a fault, just sounds the alarm rev limiter. Connect a scanner and make sure the PCM sees that your starboard engine isn't showing that you are in neutral when you shift into forward.

It's odd that your gauges are going crazy so I'd also try disconnecting your AGI box and see if the problem goes away. They are notorious for failing and maybe it is messing with your tach signal and causing the PCM to activate the rev limiter. Your Garmin / VesselView signals are not routed through the AGI box, which could explain why they are working properly.

GF?
i disconnected the agi box and nothing happened but we were thinking the same thing, that it might have something to do with the over speed and pcm thinking the boat is in neutral when itís in gear. Iím going to try and get a scanner on it in the next few days when Iím on the water to get some real time data.
ImLate is offline  
Old 08-24-2020, 05:29 PM
  #7  
Registered
Thread Starter
 
Join Date: Mar 2020
Posts: 14
Likes: 0
Received 0 Likes on 0 Posts
Default

Originally Posted by ImLate View Post
i disconnected the agi box and nothing happened but we were thinking the same thing, that it might have something to do with the over speed and pcm thinking the boat is in neutral when itís in gear. Iím going to try and get a scanner on it in the next few days when Iím on the water to get some real time data.

Alright so today I went down to the boat and put a new AGI box on the side that was giving me problems (starboard) with the tach, oil pressure and water temp and those are all back to normal. My gauges started messing up immediately after I filled the boat up with gas with the keys in the on position but not running, so maybe that messed up the agi box? Iíve seen it happen in older trucks that when the key is on and youíre fueling up it basically knocks out the instrument cluster so Iím not surprised to see this happen.

Also, the engine is not in guardian mode, itís basically sounds like a super quick blow off valve like the motor is losing spark so possible a bad coil or something else? Plugs are brand new but wires and coils are probably original if I had to guess. There is a very heavy gas smell coming from the starboard motor after running so fuel is not being burned somewhere and there are no signs of leaks anywhere around the engine or bilge or fuel lines leading up to and around the motor.

From what Iíve read this is a semi common problem. Any more insight on any specifics would be great.
ImLate is offline  
Old 06-21-2021, 11:08 AM
  #8  
Registered
 
Join Date: Mar 2020
Posts: 12
Received 2 Likes on 2 Posts
Default

Originally Posted by ImLate View Post
Alright so today I went down to the boat and put a new AGI box on the side that was giving me problems (starboard) with the tach, oil pressure and water temp and those are all back to normal. My gauges started messing up immediately after I filled the boat up with gas with the keys in the on position but not running, so maybe that messed up the agi box? Iíve seen it happen in older trucks that when the key is on and youíre fueling up it basically knocks out the instrument cluster so Iím not surprised to see this happen.

Also, the engine is not in guardian mode, itís basically sounds like a super quick blow off valve like the motor is losing spark so possible a bad coil or something else? Plugs are brand new but wires and coils are probably original if I had to guess. There is a very heavy gas smell coming from the starboard motor after running so fuel is not being burned somewhere and there are no signs of leaks anywhere around the engine or bilge or fuel lines leading up to and around the motor.

From what Iíve read this is a semi common problem. Any more insight on any specifics would be great.
Did this ever get fixed?? We have something close to this issue on a new Skater with 700's
Charli is offline  
Old 06-21-2021, 11:11 AM
  #9  
SB
Registered
iTrader: (1)
 
Join Date: Nov 2004
Location: On A Dirt Floor
Posts: 11,498
Received 1,101 Likes on 473 Posts
Default

Originally Posted by Griff View Post
Need to check fuel pressure under load. Revving to 3000rpms in neutral does require the same amount of fuel as being run under a load.
Bold above should read Doesn't.

Just fixing a mispelling in case Griff doesn't notice and edit.

​​​​​​​Any engine in neutral requires little if anything of fuel to rev to a high rpm. Load is a whole another story, it needs tons !
SB is offline  
The following users liked this post:
endeavour32 (06-21-2021)

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


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

Copyright © 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.