2005 115 Mercury 4 stroke power loss. HELP!

[sdsaw]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Excellent!

...And yes, some of us can imagine how happy you are about fixing your problem, having gone through a 3 month, intermittent problem myself

Kudos to you for posting back with the cure.
With the good description of the symptoms and the attempted fixes, to finally the cure, this post will be very helpful to others in the future.

Well done!
Scott

 

[Really Old Guy]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Sorry to hear your pain!
Good to know, I am thinking about one of these.
Your problems are giving me second thoughts.

 

[BadMerc]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Hello Bluechevyy (Curt):
I am up river from you about 5 hours (Tri-Cities,WA) and am fighting the same 115 4 stroke issue you had. It has now been 2 months since you last posted and I wanted to be sure that your motor is still "fixed". Can I assume that you checked the fuel pressure by hooking up to the valve stem located in the high pressure fuel line between the in-line filter and the Injectors? Also, you say that the motor has to be running at 1500 RPM. Is that in neutral or in gear?
Be sure and keep your address at the ready so I can send you $20 when this is over.
Thanks!
Bill

 

[bluechevyy]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Sorry for the dalay in response as I have just got back online to read over some other posts.

My motor has run very well for some time after I changed out the fuel pump. And as a follow up I checked the fuel rail pressure just the other day at 1500 RPM's as the manual instructs (in nuetral) and got about 42psi. That's good fuel pump still working.

Unfortunately, this motor has started to show signs again of the same type of issue. I was springer fishing the other day and as I took off it shot out the hole at 5500 rpms great, then decresed slowly to approxiamately 4500rpms and wouldn't go above this again. It I ease off the throttle a little bit and then slam to WOT again it will go to about 5000 rpms after that. Then again will slowly die off to 4500rpms. I'm lacking about 10mph on top end?

I'm starting to loose confidence in this engine and Mercury (or Yamaha with a black dress on) quickly! I rely on this engine to run me out 30 miles or so off shore for halibut/tuna etc. I've done it all, changed filters, new hp fuel pump, cleaned fuel rail, spark plugs new, coil new,vst filter cleaned, run with external fuel tank, taken out the anti siphon valve on the fuel tank, ~$1600.00 in shop fees. I just don't understand how they sell these engines with all these unknown issues that can't be fixed by certified mechanics at shops???? Also, I never have stale gas as I run this several times every week and go through a lot of fuel, so it's always fresh.

Unfortunately, I've never been more disappointed in a Mercury than this engine. I know it's a yamaha, but, Mercury put their name on the engine so to me the disappointment falls to them.

I don't know what to do with this engine?????? Anymore help would be greatly appreciated.

 

[bluechevyy]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Well, I think once again I found my issue this time. I found that the mechanic I took the motor to drained the fuel rail, but, didn't actually clean the injectors. I took the injectors out and took them to a local injector cleaner and for $25 each he flow tested them, ultrasonically cleaned them, replaced the orings pintle and screens and then flow tested again. The before readings were:

57, 59, 58, and 40.

After cleaning they are:

61, 61, 61 and 61.

He told me he doesn't do a lot of marine injectors, but, this was the most clogged he had ever seen one. Taking it out tomorrow and pretty sure this will fix my problem!!!! Can't wait to WOT it!!!!

 

[Doublebull127]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

bluechevy,

I have the exact same issue as you with the power surge/rpm variation. Hits 5200 r's followed by decrease to 42-4500 r's. Frustrating and loss of 10 mph.

Did the injector cleaning work for you or do you still have issues. The walleyes are biting and I'm missing the action.

THanks

 

[ron delaware]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

I am encouraged by your post do to the fact that i am having the same issues you had. I drained and removed the fuel tank,soaked injectors in Lucas fuel treatment and it now runs a little better. I couldnt go over 2200 rpm without being bogged down, now that i have soaked inj i get up to 3500 rpms but still only at 21 mph. I am leaning towards changing the fuel pump. Do i need the fuel pump, or fuel injection pump? As you know they are $ 160 difference in price. I have 2005 115 EFI 4 stroke on a 2005 Searay 185 outboard sport. I am getting discouraged. What do you think?

 

[ron delaware]

Re: 2005 115 Mercury 4 stroke fuel problems

Re: 2005 115 Mercury 4 stroke fuel problems

help

 

[rodbolt]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

and I still see shots in the dark and pokin and a hopen.
not a good way to repair this engine.
fuel rail pressure at the problem RPM and load is CRITICAL and must be checked at the problem RPM and load.
testing at 1500 RPM in nuetral is worthless unless its just clogged solid.
find a yamaha or a merc dealer with test wheel part number YB1624, now you can test the entire system at the rated RPM and load with the hull still on the trailer.
its a very very simple EFI motor,heck doesnt even have knock sensors or O2 sensors.
with YB1624 that engine should turn 5600 to 5800 RPM.
if it cant its broke.
dirty fuel is NOT a yamaha or merc issue.
with no load at 1500 RPM fuel requirement is low.
at full load and 5700 RPM fuel requirement is rather high.
loss of rail pressure will reduce RPM due to a lean air fuel ratio as will a clogged or restricted injector screen.
the above flow test is far from the worst I have seen.
so you can buy or rent the test equipment or pay an untrained tech to toss parts at it and pray.
I prefer a methodical plan with the proper test equipment so I can do it once,do it right, and I dont have to look at it again.
I dont know about mercury but the yamaha master tech program usually insures decently trained and motivated techs.
find a yamaha dealer in your area with a master tech and the proper diagnostic tools and beg them to look at this black sheep.
about the biggest issue we have with the F115 is dirty VST screens and dirty injector screens.

 

[pies1212]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Bluecevyy let us know if you fixed this problem. There are alot of postings on numerous sites with this same issue but no fixes...
I am in the same boat... we have a 2001 Mercury 115 4 stroke that we purchased from a Missouri Dealership just a few weeks ago. The water test was great 5400rpms. Now just after 3 time out the motor will not even reach 4000rpms and continues to back off and lose rpms. Mercury tech says coil wire???
I have discussed this thread with the tech.

 

[nova23zz502]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Don't do this in the water. Remove engine hood and remove intake plenum from port side of motor. Access V.S.T. assembly. Remove and disassemble. Throw the screen out from bottom of pump & install new. Clean tank very well. Must have 10 micron fuel water seperator right off of fuel tank in hull. Change small filter on back of motor. Reinstall everything and retry. Been thru this similar scenario with others. I will send you a private message with my cell #. I highly recomend end of season, remove sender and get rid of all ethenol fuel. Leave tank empty to lo. Go ahead and treat what ever is left over.

 

[mjp]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Anyone have any fix for this yet? Reading this post is exactlly what happens to me. I think I have it figured out, then it screws me. The only thing different about my 115efi 4-stroke is if I keep running it for about ten minutes, it will seem to fix itself and run better. Funny, even though it runs like crap, it still starts up every single time.

 

[pies1212]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

the merc tech that I took our 115 efi 4 stroke to called mercury to discuss the problem. He removed the fuel injectors and cycled the fuel pump with injectors out to remove any "bad gas". we're now running at 5800 rpm's again. He and Mercury blamed it on fuel that sat all winter long and varnish build up. We have removed and cleaned the tank also.
Mercury told him that in this particular motor they "see" this problem quite a bit and are blaming it on poor gas quality. It sounds like I will need to learn this "fix" so that I'm not paying 300-500 bucks every couple months... doesn't seem right!
Any updates Bluechevyy????

 

[185searay]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

I have purchased a low hour 05 SeaRay 185 with Mercury 115 EFI 4 stroke in Delaware last fall. The engine was running fine. The max rpm allowed dropped to about 3000 rpm early this season. Oil level was checked ok. I swapped interternal and external filters . I don't see any sign of water. I have tried Yamaha 10 micron, Merc 25 micron and have now another Yamaha 10 micron. A mechanic at the Yamaha dealer advised me to drain the VST tank. This engine starts perfectly and idles/runs up to 3000 rpm without issue. Then starts to shutter and won't accelerate any further. If I pump the throttle it will accelerate to 4000+ rpm. Since I am experiancing the same issues as the rest of you I wonder what to do before laying out $$$ to do this or anything else.

 

[pies1212]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

that is exactly the issue with ours, we still have the same problem after just a couple of hours runtime on the lake. pumping the throttle helps but still max rpms are 4200. i"ve had the fuel injectors cleaned twice but this doesn't "fix" the problem.???????

 

[mjp]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

On my engine, I notice that pumping the throttle helps also. I wonder if it could be the Throttle Position Sensor? I bought a manual for this motor. Still cant figure it. I think its a sensor, NOT Fuel issue. Just my thoughts at the moment. If I ever figure this out, I will post.
Mike

 

[pies1212]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Bluechevy and others-

if you boil this down to what worked, albeit for a short time, you always end up with fuel injectors clogged... what is clogging? Bad gas, water in the gas? Water could rust the fuel pump???? and we're having to "pump" due to rust build up on the injector screens?
Has anyone diagnosed this problem?

 

[185searay]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Well, we just got back from the lake. We had the boat out the other night and it ran all night at 3800 rpm. About sunset we began to cruise at 1500 rpm for a while. Just before we went to the dock we gave it a shot of gas to see if we could get the boat on plane. It wouldn't make 2200 rpm and we barely got back to the dock. The motor was spitting and sputtering.

The next morning I got in the boat, it started fine, idled at 750, and in neutral reved cleanly and freely up to 6000. I took the boat for a spin and it reved to 4000 cleanly. If I trim the engine up, so that the prop cavitates, it would spin to 6000 rpm. But with only me in the boat 3800-4000 max is all it will do under load.

Tried to take the kids tubing yesterday. With 3 adults (500 lbs) I could barely tow a 65lb kid on a tube. 3000-3200 rpms with load. I dropped off the passengers at the dock and the boat would go to 4000 again.

Towed the boat to the shop today and dropped it off..... Our local shop has no experiance with these symptoms.

If I understand this right, it sounds like the fuel pressure at the high pressure fuel pump need to be tested and if it is low the injectors need to be removed, tested for flow and cleaned. The VST needs to be cleaned and the filter replaced, The Yamaha 10 micron filter needs to be relaced as well as the Merc fuel filter on the motor. The fuel in the tank (and fuel lines) needs to be removed and the tank cleaned.

I will advise what occurs next. If you are reading this and have had the same problem as the issues described here and your problem was cured, please advise. Thanks

 

[bluechevyy]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Just a follow up for everyone, my 115 is running great. Haven't had a problem again. The only thing good to come of all of this is I think I can do just about any repair short of a motor rebuild myself. Supprisingly easy to work on outboards!! And best of all, they are clean inside!!

 

[pies1212]

Re: 2005 115 Mercury 4 stroke power loss. HELP!

Bluechevyy-

Thanks for the update! glad to hear your pain free in 2010! this thread really helped me focus on the problem and dial in the Fuelpump and injectors.
Our fuel pump had developed rust and was clogging the injectors after a very short time running.
I hope searay and others will find this helpful!

Best to you!