Boatmad.com


Reply
 
Thread Tools Display Modes
 
Old 28-04-2006, 09:07 PM   #1
Dan
On a roll
 
Dan's Avatar
 
Country: England
Location: Plymouth
Occupation: Anything in metal
Interests: Bristol Rovers, Cider & Boats
Boat name: Aqua Thunder, Badboy
Boat make: Bernico F2, Phantom 21
Engines: Merc 280efi, Merc 260efi
Cruising area: Worldwide

Join Date: Mar 2004
Location: Plymouth
Posts: 2,189
loss of rpm

Quick question, just back back in from a quick spin around and a couple of times (in about an hour)I seemed to lose around 1k rpm for around 20-30seconds then in would clear and be fine. Apart from whacking a load of carb cleaning spray in what other area should I be checking. Whether its relevant or not I dont know but I`ve got the alien cowl fitted with the 2 air scoops, I`ve fitted V.stacks and have re-jetted the carbs accordingly.
Secondly whats the turn around time at prop revalutions?

__________________

__________________
All hail to Jail Ale
Dan is offline   Reply With Quote
Old 28-04-2006, 11:15 PM   #2
Registered User
 
Maxim Gibson's Avatar
 
Country: England
Location: Cowes, Isle of Wight
Occupation: Marine engineer/electrician
Interests: Boat, Landy, and other toys :)
Boat name: Mad Max/Master Fiddler
Boat make: Phantom 18/Fletcher Bravo
Engines: Merc XR2
Cruising area: Solent/IOW

Join Date: Dec 2005
Location: Cowes, Isle of Wight
Posts: 935
Not much of a mechanic meself (yet!) but could it be droppin a cylinder now and then? Could be plugs or slight fuel starvation through the pump??
Like I say I'm not much of a mechanic but could be worth a thought??
__________________

__________________
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, grinning from ear to ear, overdosing on adrenaline and proclaiming “KINNEL!! WHAT A RIDE!!”
Maxim Gibson is offline   Reply With Quote
Old 29-04-2006, 12:15 AM   #3
The Doc
 
Captain Chaos's Avatar
 

Join Date: Mar 2004
Posts: 8,265
Dan,

I'd double check the fuel line dia and that the fuel filter is allowing sufficient flow. When I 1st fitted my Merc 200 on the Fletcher; I had a situation whereby if I ran at WOT for over (say) 2 mins I'd feel the engine start to hold back as soon as i eased on the throttle the engine would spring into life................. iet was a simple fuel restriction due to 'cheap' hose being used.

Also check the wiring that runs from the main switchbox to the ignition coils (that sequence the firing order) the wire on older mercs is utterly shite............when i replaced it, the motor ran & started a whole load better. In fact, perfic!
Captain Chaos is offline   Reply With Quote
Old 29-04-2006, 01:10 AM   #4
Registered User
 
Burty's Avatar
 
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer

Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
Send a message via AIM to Burty
air scoops in cowl big enough?
Burty is offline   Reply With Quote
Old 29-04-2006, 07:27 AM   #5
Registered User
 

Join Date: Mar 2004
Posts: 6,862
Re: loss of rpm

Coughing/Spluttering?
Less power as you gave it more throttle?
Or just "down" on power? What rpm was it doing it at, and dropping to what?
M

Quote:
Originally posted by Dan
Quick question, just back back in from a quick spin around and a couple of times (in about an hour)I seemed to lose around 1k rpm for around 20-30seconds then in would clear and be fine. Apart from whacking a load of carb cleaning spray in what other area should I be checking. Whether its relevant or not I dont know but I`ve got the alien cowl fitted with the 2 air scoops, I`ve fitted V.stacks and have re-jetted the carbs accordingly.
Secondly whats the turn around time at prop revalutions?

Matt is offline   Reply With Quote
Old 29-04-2006, 08:39 AM   #6
Dan
On a roll
 
Dan's Avatar
 
Country: England
Location: Plymouth
Occupation: Anything in metal
Interests: Bristol Rovers, Cider & Boats
Boat name: Aqua Thunder, Badboy
Boat make: Bernico F2, Phantom 21
Engines: Merc 280efi, Merc 260efi
Cruising area: Worldwide

Join Date: Mar 2004
Location: Plymouth
Posts: 2,189
Re: Re: loss of rpm

Quote:
Originally posted by Matt
Coughing/Spluttering?
Less power as you gave it more throttle?
Or just "down" on power? What rpm was it doing it at, and dropping to what?
M
Matt, no coughing or spluttering at all, and it didnt happen as soon as I reached 5800rpm infcat I had been at wot for a while so not really a case of more throttle less power, as you say it just drops down on power. I guess I was around 5800 then a couple of times it just dropped to just below 5, then after a few seconds it picked back up.
__________________
All hail to Jail Ale
Dan is offline   Reply With Quote
Old 29-04-2006, 08:40 AM   #7
Dan
On a roll
 
Dan's Avatar
 
Country: England
Location: Plymouth
Occupation: Anything in metal
Interests: Bristol Rovers, Cider & Boats
Boat name: Aqua Thunder, Badboy
Boat make: Bernico F2, Phantom 21
Engines: Merc 280efi, Merc 260efi
Cruising area: Worldwide

Join Date: Mar 2004
Location: Plymouth
Posts: 2,189
Quote:
Originally posted by Burty
air scoops in cowl big enough?
I have cut them out since it was fitted, any millage in cutting a hole in the front and fitting the face plate??
__________________
All hail to Jail Ale
Dan is offline   Reply With Quote
Old 29-04-2006, 09:18 AM   #8
Registered User
 
divertom's Avatar
 
Country: UK
Location: Plymouth
Occupation: Student numptee
Interests: Lots of stuff
Boat name: Rough Rider
Boat make: 21ft ring
Engines: Mercury 275hp

Join Date: Apr 2006
Location: Plymouth
Posts: 130
hi Dan,
I had this problem on a dive boat I was on a few years ago. Cant say its the same problem that your having but the problem I was having was that the pulse line to the fuel pump was clogged up (due to using frikin mineral oil(crappy stuff)), so at high rpm the engine would after a while die down only slightly. Also I am sure yours are fine but I would check the one-way valves in the fuel pumps just to see if there are any tale tale signs there.
Anyways hope you fix it and see you on the water soon
__________________
If practice makes perfect and nobodys perfect then why the hell practice!!!!
divertom is offline   Reply With Quote
Old 29-04-2006, 09:33 AM   #9
Registered User
 
Burty's Avatar
 
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer

Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
Send a message via AIM to Burty
Quote:
Originally posted by Dan
I have cut them out since it was fitted, any millage in cutting a hole in the front and fitting the face plate??
Prolly not then, i only have the side scoops and i dont suffer.
you need someone in the back when this is happening to check to see fuel lines / priming bulb are not getting sucked in. changed your fuel filter lately? charged your battery?
Burty is offline   Reply With Quote
Old 29-04-2006, 09:37 AM   #10
Dan
On a roll
 
Dan's Avatar
 
Country: England
Location: Plymouth
Occupation: Anything in metal
Interests: Bristol Rovers, Cider & Boats
Boat name: Aqua Thunder, Badboy
Boat make: Bernico F2, Phantom 21
Engines: Merc 280efi, Merc 260efi
Cruising area: Worldwide

Join Date: Mar 2004
Location: Plymouth
Posts: 2,189
Quote:
Originally posted by Burty
Prolly not then, i only have the side scoops and i dont suffer.
you need someone in the back when this is happening to check to see fuel lines / priming bulb are not getting sucked in. changed your fuel filter lately? charged your battery?
I`m gunna go and get a new filter and fuel lines today, as for the battery, yep all charged.
Burty, you still coming down tomorrow?
__________________
All hail to Jail Ale
Dan is offline   Reply With Quote
Old 29-04-2006, 11:21 PM   #11
Registered User
 
Burty's Avatar
 
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer

Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
Send a message via AIM to Burty
no mate, they went today instead and i was busy
Burty is offline   Reply With Quote
Old 20-05-2006, 10:01 AM   #12
Dan
On a roll
 
Dan's Avatar
 
Country: England
Location: Plymouth
Occupation: Anything in metal
Interests: Bristol Rovers, Cider & Boats
Boat name: Aqua Thunder, Badboy
Boat make: Bernico F2, Phantom 21
Engines: Merc 280efi, Merc 260efi
Cruising area: Worldwide

Join Date: Mar 2004
Location: Plymouth
Posts: 2,189
Sorry to drag this one open again but, fitted all new fuel lines and filters, when out the other day and thought the problem was fixed until mid air revjust died right down (at WOT) and didnt come back up (which meant a very slow crawl back from the breakwater). So, I`ve got a rectifier (thank you very much ) which I`ll stick on today, I`ve checked the plugs they look ok to the untrained eye had a bit of what looked like oil on them. If its still the same after the rectifier I`ll change the stator (and the plugs & leads just to be on the safe side) after than any sugggestions? The engine is not mis firing at all.
Dont know if its relevant or not but when I fitted the stacks I re-jetted the carbs (couple of sizes I think) and I premix at 30-1.
__________________
All hail to Jail Ale
Dan is offline   Reply With Quote
Old 20-05-2006, 10:06 AM   #13
Registered User
 
Burty's Avatar
 
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer

Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
Send a message via AIM to Burty
30:1 seems a bit much
but prolly not the cause of problem. you can run 40:1 easy which will give you more power.
Burty is offline   Reply With Quote
Old 20-05-2006, 10:28 AM   #14
Dan
On a roll
 
Dan's Avatar
 
Country: England
Location: Plymouth
Occupation: Anything in metal
Interests: Bristol Rovers, Cider & Boats
Boat name: Aqua Thunder, Badboy
Boat make: Bernico F2, Phantom 21
Engines: Merc 280efi, Merc 260efi
Cruising area: Worldwide

Join Date: Mar 2004
Location: Plymouth
Posts: 2,189
Quote:
Originally posted by Burty
30:1 seems a bit much
but prolly not the cause of problem. you can run 40:1 easy which will give you more power.
Ran 30:1 last year so I`m pretty sure its not that.
__________________
All hail to Jail Ale
Dan is offline   Reply With Quote
Old 20-05-2006, 11:17 AM   #15
hello
 

Join Date: Mar 2004
Posts: 2,739
40:1 its might not be the cause of your problem but your just chucking money away by running 30:1.

If it was rich due to re jetting the carbs it would lose revs on top all the time not spuradically. Check all the wiring around the switch boxxes rectifier stator etc. Look for bad connections, damaged insulation etc. A wire might have rubbed through and be shorting on the block.

Does the tach jump around at all? If it does I would look at the rectifier.

Could also be the stator!!!
JamesM is offline   Reply With Quote
Old 20-05-2006, 11:28 AM   #16
Registered User
 
Burty's Avatar
 
Country: UK
Location: Weston Super Mare
Occupation: Electrical Engineer

Join Date: Mar 2004
Location: Weston Super Mare
Posts: 6,351
Send a message via AIM to Burty
Quote:
Originally posted by Johnny Boat Dude
40:1 its might not be the cause of your problem but your just chucking money away by running 30:1.
and losing power dude
Burty is offline   Reply With Quote
Old 20-05-2006, 03:40 PM   #17
Dan
On a roll
 
Dan's Avatar
 
Country: England
Location: Plymouth
Occupation: Anything in metal
Interests: Bristol Rovers, Cider & Boats
Boat name: Aqua Thunder, Badboy
Boat make: Bernico F2, Phantom 21
Engines: Merc 280efi, Merc 260efi
Cruising area: Worldwide

Join Date: Mar 2004
Location: Plymouth
Posts: 2,189
Quote:
Originally posted by Johnny Boat Dude
40:1 its might not be the cause of your problem but your just chucking money away by running 30:1.

If it was rich due to re jetting the carbs it would lose revs on top all the time not spuradically. Check all the wiring around the switch boxxes rectifier stator etc. Look for bad connections, damaged insulation etc. A wire might have rubbed through and be shorting on the block.

Does the tach jump around at all? If it does I would look at the rectifier.

Could also be the stator!!!
No tachs fine no jumping at all. Is there any way of testing the stator or is it a case of trying a new one?
__________________
All hail to Jail Ale
Dan is offline   Reply With Quote
Old 20-05-2006, 05:44 PM   #18
Registered User
 
Maxim Gibson's Avatar
 
Country: England
Location: Cowes, Isle of Wight
Occupation: Marine engineer/electrician
Interests: Boat, Landy, and other toys :)
Boat name: Mad Max/Master Fiddler
Boat make: Phantom 18/Fletcher Bravo
Engines: Merc XR2
Cruising area: Solent/IOW

Join Date: Dec 2005
Location: Cowes, Isle of Wight
Posts: 935
Quote:
Originally posted by Dan
I`ve checked the plugs they look ok to the untrained eye had a bit of what looked like oil on them.
As long as they're not cracked anywhere, rusty or badly soiled and the gap in the top should be about the thicknes of the card a fag packet's made of....
Attached Images
 
__________________
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, grinning from ear to ear, overdosing on adrenaline and proclaiming “KINNEL!! WHAT A RIDE!!”
Maxim Gibson is offline   Reply With Quote
Old 20-05-2006, 06:41 PM   #19
Registered User
 
scottyboy's Avatar
 
Country: United kingdom
Location: West Sussex
Occupation: Grease Monkey
Interests: Makin my boat faster!
Boat name: S.B Racing
Boat make: Ocke mannerfelt canopied B23 / Zapcat
Engines: Merc 200XS Gen 2 / Tohatsu 50
Cruising area: littlehampton/Southampton

Join Date: Jan 2005
Location: West Sussex
Posts: 2,652
Dan,

Does it rev fine out of gear and when you put it in gear it dies?
__________________
Class 3C Mono EPA National speed record holder 95.35 mph Avg!
scottyboy is offline   Reply With Quote
Old 20-05-2006, 06:48 PM   #20
hello
 

Join Date: Mar 2004
Posts: 2,739
Quote:
Originally posted by Dan
No tachs fine no jumping at all. Is there any way of testing the stator or is it a case of trying a new one?
Trouble is it mite only be breaking down when hot or due to vibration.

If you knew which wires went to each coil I supose you could check the DC resistance of each one to see if there's an odd one out, maybe!!!
__________________

JamesM is offline   Reply With Quote
Reply

Thread Tools
Display Modes

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 Off
Pingbacks are Off
Refbacks are Off


Powered by vBadvanced CMPS v3.2.3

All times are GMT +1. The time now is 05:15 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
×