2005 115 Mercury 4 stroke power loss. HELP!

bluechevyy

Seaman
Joined
Oct 23, 2009
Messages
50
Please anyone that can help! I have a 2005 Mercury 4 stroke optimax (which I am told the power head is a Yamaha). 200hrs on the engine is all.

I am experiencing a major power loss at full throttle. One day it ran great, the next it runs at ~3000rpms max throttle. You can feel it stutter as it's accelerating to the 3000rpms. Also, it starts awesome and ides pretty good. You can feel a little more vibration than you use to at idle.

Here is what I have done so far. I have replace the spark plugs, check the oil level etc. Made sure all electrical connections are plugged in all the way in the engine. I checked spark with an inline checker and also at the output of the plug and all looked good to me. I changed out water separator filter and internal filter. Found nothing. Gas is not old or water contaminated. Also I took it out and separated my fuel system all together by hooking up an external tank and the problem was exactly the same.

Here's where the frustration comes in. I took it in to a local marine dealer and they put it on their so called diagnostics tool and it told them the crank shaft position sensor was bad. So, 3 and a half weeks later I get the boat back with a bill for just short of $700. Still does the same thing. I took it to another marine dealer and they did "extensive diagnostics" and determined it was the #2 & 3 ignition coal. They replaced the part and a week later and $590 later it still does the same thing. I'm into a fix almost $1300 and I have no faith that they know what's wrong. Please help.

Now it's back to the 2nd marine dealer for the total of the 3rd visist and they pulled the injectors to clean the screens. Of course they don't have the orings to put them back! Another week of waiting parts. The guy said he wasn't convinced the injectors were the problem either. HELP HELP please. I truely love my boat and going out on it on a regular basis,but, I'm starting to think I stepped in to deep on this one. Who would expect a motor only 4 yrs old to have this costly of problems. I don't neglect maintinance on it either. I run fuel saver change oil regularily etc.

I'm trying to get my 5, 3, and 2 yr old girls out to fish before winter sets in.:confused:

Thanks in advance for any ideas!!!!

Curt (out of Portland, OR)
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Re: 2005 115 Mercury 4 stroke power loss. HELP!

To get the best answer lets get a better idea of what you have.. a Optimax 115 is a 3 cylinder 2 stroke DFI engine made by Mercury and the older 115 4 cylinder EFI was a 4 stroke made by Yamaha...so is it a 3 or 4 cylinder? Are you checking oil in oil tank or in crankcase? I am thinking you have a EFI since you said you changed oil.
 

sdsaw

Petty Officer 2nd Class
Joined
Aug 19, 2007
Messages
188
Re: 2005 115 Mercury 4 stroke power loss. HELP!

Well, if you do have a 115hp fourstroke, there was no mention of a VST(vapor separating tank) service.
Do a search over on the Yamaha/Suzuki section for "VST Cleaning" and you will find many posts referring to this common problem with the EFI motors

Here's one of the posts:
http://forums.iboats.com/showthread.php?t=352855&highlight=VST+cleaning

Also, check the thermostat

Good luck!
 

bluechevyy

Seaman
Joined
Oct 23, 2009
Messages
50
Re: 2005 115 Mercury 4 stroke power loss. HELP!

I have the 4stroke made by Yamaha. It is a 4 cylendar engine.
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,589
Re: 2005 115 Mercury 4 stroke power loss. HELP!

I went back over your posting and you stated they changed 2 & 3 coil, this is confusing as engine has only 2 coils, and top fires 1 & 3 and 2 & 4 at same time. I have seen only 3 problems on these engines: (A).. injectors (B).. harness where it plugs into ECM (C)..oil pressure switch. Changing the screens in injectors really does nothing but remove any debris in filter, they(injectors) must be flowed ,cleaned and balanced. I suggest you send them to Tony/Linda @ Brucato (Brucatosvs.com) as they will do all the above for about the price of 1 replacment injector. The harness probem is simple as harness unplugs itself at top, engine will run,show no code troubles, and miss like it has plugs fouling in the 3000 rpm range. The oil switch is a simple check, just unplug it and run it , if problem goes away replace it. Is your oil/hot horn working? Another thing it could be is the temp switchas if bad it will retard timing but this wont cause a stutter/miss just lack of power.
 

blackbox

Seaman
Joined
Feb 24, 2009
Messages
74
Re: 2005 115 Mercury 4 stroke power loss. HELP!

faztbullet gave soom great info. sorry for your motor problems. sounds like fuel system issues. hope the repair shop gets you going!
yamaha recomends a 10 micron pre-filter. if you donot have one, it may be a good time to have one installed. a good filter may prevent other fuel problems.
 

bluechevyy

Seaman
Joined
Oct 23, 2009
Messages
50
Re: 2005 115 Mercury 4 stroke power loss. HELP!

The motor does have an internal fuel filter in addition to the water separating filter (external). Currently I am waiting for the shop. They currently have pulled the injectors and are flushing them, but, waiting for o-rings kits before replacing them. Said they would be in by late this week. Then they are going to have me come down and water test it with me present.

Thanks for all the input so far from everyone!! I am going to follow up on the harness to ECM and checking the oil pressure switch if the fuel injector cleaning doesn't help.

I will keep you posted on the outcome!! It's killing me, I'm a die hard fisherman and I've been without my 20' Northriver in action for over a month now!!!!

Curt
 

BW3D

Recruit
Joined
Oct 26, 2009
Messages
2
Re: 2005 115 Mercury 4 stroke power loss. HELP!

I had the same problem with my Merc. 40hp 4-stroke....Turned out that it was an electricla problem....Cant remember the mane of the part replace but it charges the battery. Turned out that it wasnt charging the battery and in turn the fuel injectors and spark plugs werent getting enough power at higher RPM's. I will try to rmember the name of the part and post it for you.
 

bill and doris

Seaman Apprentice
Joined
Mar 7, 2009
Messages
48
Re: 2005 115 Mercury 4 stroke power loss. HELP!

When my 115 Merc 4 stroke acting like yours I chased everything. After 2 years the fuel pump finally quit completely. The folks here were able to direct me where to get the parts breakdown on the motor and what the part's actual part number was. Took about an hour to get manafold off and home. Fuel pump is hidden behind manifold. Pulled pump and replaced. Had everything reinstalled back on motor in about an hour. Runs perfect now.
 

bluechevyy

Seaman
Joined
Oct 23, 2009
Messages
50
Re: 2005 115 Mercury 4 stroke power loss. HELP!

Well after all the time and $$$$ ($1200), the problem was what I thought it was in the beginning, just needed the injectors cleaned. What a waste. There should be some sort of recourse on these marine stores that are wasting your money on parts that are perfectly good. Well I will for sure pass along to ALL my boat friends not to do business with the company I first dealt with.

Thanks everyone for your great feedback and help. It gave me lots of ideas and things to look at.

I'll chalk it up to a bad experience!!

Bottom line is I'm back on the water and lovin' it!!!

Thanks,

Curt
 

bluechevyy

Seaman
Joined
Oct 23, 2009
Messages
50
Re: 2005 115 Mercury 4 stroke power loss. HELP!

Well I got 1.5 trips out of it at I would say 95%. The problem is back and I only get 3200rpms again. Realy frustrating. I thought by buying a 3yr old motor I wouldn't run into constant problems for quite a long time.
 

rodbolt

Supreme Mariner
Joined
Sep 1, 2003
Messages
20,066
Re: 2005 115 Mercury 4 stroke power loss. HELP!

and I still see no mention of VST cleaning or mechanical fuel pump diaphram inspection.
that debris in the injector screens came from someplace,most likly the VST.
unless they are damaged the injector orings are reusable.
yamaha added a 10 micron inline fuel filter between the lift pump and the VST about 2006, you may wish to add it to your rig.
vst filter cleaning is part of yearly routine maint, its in your owners manual maint guide.
no one even mentioned fuel rail pressure checks.
} rail pressure is absolutly CRITICAL yet not monitored by the ECU.
never seen an ign coil failure on the F115 but like it was pointed out, one coil fires cyl 1&4 the other fires 2&3. actually 1&4 and 2&3 fire simultaeously and if the primary or secondary windings fail you will lose spark on 2 cylinders.
its not a motor issue, sounds more like a dealership lack of training issue.
thats something neither merc nor yamaha can control but yamaha does place a lot of incentive on dealers to train techs.
 

bluechevyy

Seaman
Joined
Oct 23, 2009
Messages
50
Re: 2005 115 Mercury 4 stroke power loss. HELP!

So I now took the VST out (fairly large job for a yearly service)and inspected the high pressure fuel filter and found very little debris in it. Can't amagine what a dealer would charge for all that work to get out the VST. Across the screen I saw maybe 5-10% covered with some fine debris. Cleaned out and replaced. Will take out and test run Thursday. But, my hopes are not up, I didn't see much of a sign that would decrease the power as much as I'm loosing. We'll see.

You metioned the mechanical fuel pump diaphram inspection. What exactly is to be done here. Is this for the low pressure fuel pump? Also, before going any further I will be checking fuel rail pressure. And, yes, I got my firing order wrong on the original post.
 

bluechevyy

Seaman
Joined
Oct 23, 2009
Messages
50
Re: 2005 115 Mercury 4 stroke power loss. HELP!

Please, still looking for further help on this! Again a recap to what I've done so far:
-New water separating filter
-new inline 10um filter.
-Taken out the VST and checked/cleaned the filter on the bottom of the fuel pump.Didn't find much debris at all.
-new plugs (2x's me once and shop again)
-Run boat on external fuel tank (did not change sympoms)
-Marine shop changed the crank shaft position sensor (didn't help)
-Marine shop changed one of the coils (didn't help)

How would I know if the fuel pump was failing? Any further suggestions on where to proceed next?? Help still??
 

sdsaw

Petty Officer 2nd Class
Joined
Aug 19, 2007
Messages
188
Re: 2005 115 Mercury 4 stroke power loss. HELP!

That marine shop is sure throwing a lot of new parts trying to track down your problem :eek:
IMO, you are wasting your $$$ throwing new parts at it.

Since it sounds as if it ran good right after you had the injectors cleaned but the problem returned in a few trips, I'm thinking that once again you have a dirty injector(s).
Here's a DIY procedure that I would be trying next:
http://forums.iboats.com/showthread.php?t=344859
 

shadowcrest5

Cadet
Joined
Sep 24, 2009
Messages
14
Re: 2005 115 Mercury 4 stroke power loss. HELP!

Hey Bluechevyy,
Welcome to OUR pain and suffering.Yes I said OUR. I also have the same exact motor.Make , year, model ,115 hp efi. I started my thread last summer ....Sept.24th to be exact. Feel free to look it up. We have 2 others that I know of ...MJP, and Bigjohn1. You can read there nightmare stories as well.
I MAY have GOOD NEWS. First I too wasted money at a marine dealer and tech. If you read MJP's post on Oct 27th 2009 he too spent lots of time and money. He finally went with a last resort (PIECE of his puzzle) and tried what someone said was there fix........THE THERMOSTAT. This makes 2 people now with OUR problem. And yet a un-likely fix. BUT IT WORKED .......PERIOD!!!!!
As of your last post you just re-capped what you had done.You did not mention if cleaning the VST box had ANY change. If so .......what??
I live in Wisconsin ....so I will wait until early spring to start changing parts ....MYSELF. AT NO TIME have I heard that ANY Marine Dealer "FIXED" our problem . And you can bet there are "LOTS OF US" out there. Don't hold your breath to receive a "re-call" letter from Merc. on this GROWING issue.
Good Luck.....please post ANY positive feedback on this issue...........................Shadowcrest5
 

shadowcrest5

Cadet
Joined
Sep 24, 2009
Messages
14
Re: 2005 115 Mercury 4 stroke power loss. HELP!

Hello again Bluechevyy,
You stated that you placed a 10um inline filter.WHERE EXACTLY did you place it, or between what existing components is it. I take it this is a fuel/water filter and it is installed.....IN ADDITION TO.....the existing factory filter.Not in place of factory filter.Please be specific.Purchased from what location,or company??
Thanks Shadowcrest5
 

bluechevyy

Seaman
Joined
Oct 23, 2009
Messages
50
Re: 2005 115 Mercury 4 stroke power loss. HELP!

Well, I think I may have the problem dialed in. Thanks by the way to the last few posts. Shadowcrest5 my boat has the water separating filter and then folowed by an internal 10um filter just prior to the low pressure fuel pump. I also checked the thermostat and tested it externally in a pot of water and it is functioning fine.

HERE IS THE GOOD NEWS! I think I solved my problem. I have an intermittent problem with my high pressure fuel pump (same as "bill and Doris" said they had). I tested it and it measure approximately 36psi. Then I read further in the service manual and it says to test at 1500rpms. So I did this again. This time I could only get 12psi. Retested 6-7 times and it was exactly the same. I have a new fuel pump on order and 2nd day air. Will install this coming weekend!

I will report back to if this is the problem after install and test run!!

Thank you truely to everyone with suggestions and this is an expensive hobby and FRUSTRATING as all heck!!!

Curt
 

bluechevyy

Seaman
Joined
Oct 23, 2009
Messages
50
Re: 2005 115 Mercury 4 stroke power loss. HELP!

Well, after all this time I finally found the problem!!!! I wanted to make sure and return to the post and let you all know what I found in hopes it helps someone else again!

My fuel pump was intermittently failing. I replaced it and ran it for about 45 minutes yesterday on the Willamette and it ran better than ever. Averaged about 5700.

You have no idea how happy I am!!!:) And to add to the great fealing of having a fixed boat my Dad caught a 42" keeper sturgeon as well while we were out.

Thanks again to all you on iboats forums for helping people out with there problems. I have learned a great deal from all the help you have given me and will try and return the favor to some others!!! :)
 

NFA

Petty Officer 2nd Class
Joined
Nov 26, 2003
Messages
158
Re: 2005 115 Mercury 4 stroke power loss. HELP!

What a great read. Here's to many more outings Chevy!

Well done.
 
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