Mercury 60hp 4 stroke EFI Bigfoot issues

RPM22

Recruit
Joined
Dec 23, 2014
Messages
5
I have recently purchased a 2007 Mercury 60 hp 4-stroke EFI, and it is unable to get over 4000rpm - although out of gear it can easily get to 6000. I know that it has some kind of protection system, perhaps this has triggered? How best to untrigger this? It will need a full overhaul, new impeller etc perhaps its is overheating slightly? I have ordered a manual, but thought I'd get ahead on my research.
Richard in Los Angeles
 

1nebel0

Chief Petty Officer
Joined
Nov 28, 2005
Messages
512
Any motor can rev up in neutral....when you put a load on motors it is a different story....Many tests to do but the first question is what size and weight boat and what size prop are you runninng...... First one is compression always....can't tune a motor with a low cylinder..Your motor is fairly new in the year it was made however I always want to know that compression is good and within 10% of the lowest to the highest... Next, check for spark on all cylinders...That requires a qood spark testor... I use the same one the shops use..Stephens...They are expensive but that is what I use....Next comes testing trigger, and stator using a DVM with a Peak Voltage Adapter....Fuel Pressure needs to be checked given it being an EFI...These tests are what I would do....CDI on line has all the spec's but you need to have the correct tools to do the work....Like any trade tools are importantan and the shop manual is just as important...let other chime in on their thoughts...
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Wow, you "think" it needs an overhaul, you "think" it has a protection system (actually it does), you "think" it needs an impeller, you "think" it is overheating and yet you think the protection system is at fault and want to disable it. This is not getting ahead on your research -- it is grasping at straws. Just so you know, the protection system is a multi-part system that monitors engine oil pressure, engine temperature, and engine rpm just to name a few of the really important features. The over speed part of the system prevents the engine from being over reved which you nearly did when you put it in neutral and spun it up to 6000 rpm with no load. That constitutes engine abuse. So with the importance of this "protection system" why would you want to disable it. If the engine is really in that bad a shape, do you think it wise to disable this system or even think it is the root cause of the problem. What does overheating slightly mean? It is either overheating or it is not. This is like your wife or girl friend being a little bit pregnant. Why not wait until you get your service manual to ask unanswerable questions like this. You need to actually know what problems the engine has. Compression numbers are needed as are oil pressure and actual water temperature readings. Have you pulled the spark plugs and checked them? Spark intensity on all cylinders must be up to spec. Fuel pump and line pressures are needed. Fuel injector cleaning may be necessary. Finally, unless you have the computer software and other equipment required to work on a four-stroke fuel injected engine there is not much "electrical" diagnosing you can do.
 

RPM22

Recruit
Joined
Dec 23, 2014
Messages
5
Dear 'Silver tip' - thank you for your thoughts, perhaps a little 'heavier' than required or needed. This is a new engine to me, I normally run and maintain two 7.4 lt Mercrusier I/O, which don't have all these bells and whistles, having carburettors. I already know that this engine has a guardian protection system, I'm trying to learn about it from those who have had experience with it, as I can't find any Mercury literature on it. I already know that the impeller needs to be replaced, (six years old) I was merely asking if anyone thought that this was likely to be what set off the Guardian system? I don't want to 'disable' the system, the word i used was 'untrigger'. I imagine it's overheating because of the impeller being old, but did not realise that making this conclusion was a crime to some? I have only owned the Boston Whaler Montauk 150 for six days, and driven it in the water for fifteen minutes, so obviously there is a lot I have to do, including all the things you mentioned.
 

RPM22

Recruit
Joined
Dec 23, 2014
Messages
5
To 1nebe10 - thank you for your interest, the engine is on a Boston Whaler Montauk 15 foot, and the prop is a Mercruiser 14-pitch Veneance. The boat has hardly been used since it was first bought, so I realise I will be doing a full overhaul - but thanks for your suggestions, they are on my to-do list.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Its not in Guardian or protection mode..... Check items as posted earlier, spark,spark plug for fouling,compression and then fuel pressure and check injectors,all will be in manual.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Sorry you took my comments as being overly tough on you. The word "wow" can, and does in this case, mean surprise rather than a "dig" at you. As I mentioned in my previous post, everything you mentioned as an issue was stated as a "possibility". The term "full overhaul" would likely draw a surprise reaction from any mechanic since you have no evidence whatsoever that this is necessary. Not understanding how the protection system works is understandable but the mere fact you wanted to reset/untrigger/disable it is surprising since you didn't mention anything about any alarms from it. Then you tell us you run and maintain big block I/O's which makes the fact you ran the outboard at 6000 rpm in neutral a surprise as well. Running any engine at high rpm in neutral is not a good thing. So -- I do apologize if you took this a little but too much to heart. The fact remains however that to get meaningful help with engine issues the answers to those questions depend on details since we cannot see, hear or diagnose your engine. Four stroke outboards are no different than an auto-based inboard or I/O engine in that they suck, squeeze, bang and blow and utilize many of the same components.
 

RPM22

Recruit
Joined
Dec 23, 2014
Messages
5
Thanks Silvertip, from my experience, any outboard that has hardly been used, and has been grossly neglected is likely to need a full overhaul, plugs, lower unit oil, impeller and or water pump body, to me that would just be routine to catch up for seven years neglect. I did not give you the full info which made me think the gauardian system had triggered, twice underway at 4000 the alarm went off and the revs dived to about 2000. I gave it alittle time then slowly went back up to 4000, fortunately the trip was only fifteen minutes long before being hauled. I understand your concern about 6000 revs, but this was only once for a brief second, to see if it was a gearbox problem or not. I have since discovered that the vent was not cracked open on the portable fuel tank, so that may have starved the engine of fuel, but then it wouldn't have carried on after slowing down? As you see i have much to learn, and the Mercury manual should be here soon. Talking of checking the plugs, there is so much stuff attached to this engine, I can't even get a finger in to pull off the plug leads, is there a secret to this, or a special tool?
Thanks in advance ...
 
Top