Merc 4 stroke 115hp problems

[captadamr]

Hello to all, my first post, I wish it was on a happier note.

I have a 220B Angler 2001. It has twin 2002 115hp 4 stroke EFi's on it. The motors only have 150 hrs on them. They were used and then sat for almost a year, and barely used.
On the test run they got to high 4000rpms, but blamed it on poor propage
(15P Blackmaxes). Took it out and fueled it up, and noticed a drop of rpms, decided to change the filters, and now the motors will not get over 2500rpm @ WOT. Took it to the mechanic today and he said both engines are only running on 2 cylinders. Checked the coils and they were not the problems.
He claims that it is the ignition system (pcm). Is it possible that this same problem can be occuring on both engines. I just find it hard to belive that both motors have an ignition problem at the same time.

If anyone has any insight into this problem, as it is a holiday here (bahamas) and i wont get to talk to mech til wend.

Thanks for you help

Capt Adam R.

 

[Bigjohn1]

Re: Merc 4 stroke 115hp problems

I will have to look in my factory manual tonight as it lists the rpm limits and associated cause(s). If you have access to a Merc factory manual, you can see it there. I do seem to recall the book pointing to the ECM's for this but will check it out. You live in a very harsh environment for anything electrical or electronics to be sitting around unused. Sit tight.

 

[captadamr]

Re: Merc 4 stroke 115hp problems

thanks, I will be intrested in your findings. I do not have the merc manuals, I need to order one, where can I buy them from?

 

[Bigjohn1]

Re: Merc 4 stroke 115hp problems

The following came from chapter 2 of the official factory manual titled,

“Mercury/Mariner/Mercury Service Manual 115 Four Stroke Electronic fuel injection Starting model year 2001 starting serial number OT178500”

From a troubleshooting standpoint, everything is pointing to the ECM saying you have low oil pressure.

When TWO cylinders cut out (#1 and #4) and rpm’s are limited to 2,000, the ECM is getting the message that the engine is overheating. Now, I realize you said you are getting 2,500rpm but there could be a combination of things going on that would make your rpm’s different (Bahamas heat and humidity, tach not 100% accurate, etc).

I was not there with you to hear the mechanic’s exact diagnosis but from the way you describe it, he quickly blames the ECM’s after only testing the coils. If the oil pressure switch was sending faulty signals to the ECM, it could be tricking the computer into placing the engine into safe mode (2 cylinders cut out and 2,000 rpm limit). Could you have a faulty oil pump and/or mechanical damage which truly is giving you low oil pressure? I cannot say for sure but it’s doubtful given the history and light use of these engines.

Actually, for your problem, the book says to check the following (in order):

1. Battery voltage
2. Spark plugs
3. Resistance of spark plug wires

After these easy things have been eliminated, then it’s on to testing the various ignition components under the cowel. The trouble here for the backyard guy is, you need the Mercury factory test adapters which interface between a standard multimeter and the wiring harness. I am not a factory mechanic and it’s quite possible your mechanic could know from experience that in the majority of cases he’s seen with these symptoms, it’s normally the ECM which has gone bad. I agree with you though in that it seems strange both would be bad at the same time. I am wondering if the boat has recently either been struck by lightning or been in close proximity to a location which was struck. This would likely fry both ECM’s at the same time.

I would love to read input from factory mechanics who have worked on this engine. This Yamaha power head/Mercury lower unit hybrid engine seems to have an excellent track record during the 5-6 years they were built. It is very difficult to google anything on the net reporting widespread problems. The worst I have seen is shift clunk and prop rattle at low rpm; you likely have not experienced this since you are running aluminum props though. If you switch to 4-blade ss units (which you probably would benefit from going offshore) just make sure you fit them with Flo-Torq III hubs.

I hope this helps, those ECM’s are expensive so I would talk to the mechanic and ask the process he used to determine the fault lies at the ECM first. He’ll probably be right in the end but it will make you feel better given the potential financial hit to your wallet that you’re up against. I hope for your sake it is some simple problem (like a bad battery).

Good luck

 

[captadamr]

Re: Merc 4 stroke 115hp problems

thanks for the reply,

Both engines are "peeing" extremly well and the water pressure had not been low during runnning, except when we were performing sharp turn with the fuel tank less than 15% full, only then did one engine have a water pressure drop, and upon slowing down, it came back up and no alarms sounded. the engine oil level is at "full".
Its weird that the rpms dropped progressivly from 4000 to 2000, and now wont get over 2000. Almost seems like a fuel issue, but mechanic insists its not.

 

[Bigjohn1]

Re: Merc 4 stroke 115hp problems

Understand, but rememeber, we are talking oil pressure, not water pressure. Even though it's peeing strongly, you "could" have low oil pressure. The oil pressure switch sends a message to the ECM to reduce rpm's to 2,000 when oil pressure is reduced below 21.78 psi. This does not sound fuel-related at all to me the more we talk about it.

 

[captadamr]

Re: Merc 4 stroke 115hp problems

Is there any way to reset the ecm out of the failsafe mode, to rule out total ECM failure.
I will let the mechanic test the oil pressure sender to see if it is giving off a faulty reading.
Is there a more grim senerio that I am making oil, and therefore reducing the viscosity of the oil? Is there anyway for gas to find its way into the engine oil and cause a low pressure reading? (Edit: Isnt the only way gas/oil mixing can occur is with blown piston rings, and wouldnt it be a smoky mess?)

 

[Bigjohn1]

Re: Merc 4 stroke 115hp problems

No way to reset ECM that I know of, it is sealed un-repairable unit. This particular engine cannot be "read" on a computer. Rather, a simple 1-bulb diagnostic light is hooked up to the engine wiring harness. The "pattern" of light flashes is compared to a table in the factory manual to tell the mechanic what is going on. I bought my manual at my Merc dealer (around $60), I am not sure if they are available online or not.

One more thing on the oil pressure switch - to "test" the switch, he will be looking for continuity on a multimeter below 21.78 psi. He will need to remove the switch and pressurize it with a hand pump FYI.

Good luck

 

[captadamr]

Re: Merc 4 stroke 115hp problems

im sure they will do it bahamian style, take the old one out and try a brand new one to see if it works

 

[captadamr]

Re: Merc 4 stroke 115hp problems

Does the manual say what voltage it goes into safe mode at? The mechanic didnt come today (not suprised), and I would like to check the voltage.

Thanks

 

[Bigjohn1]

Re: Merc 4 stroke 115hp problems

It is not a voltage value that causes it to go into safe mode (#1 and #4 cut and rpm's limited to 2,000). It is rather a temperature value; if the engine reaches 194 degrees, that is what causes it. Assuming your plugs and wires are good, I think your ECM is getting tricked into thinking the engine is overheated. Are you 1000% sure the plugs are good?

I have read of a few reports by owners who claim all was well out there on the water then all of the sudden a plug just fouled and went bad out of nowhere. I have over 500 hours on mine though and this has never happened to me.

I still think given the fact that the exact same symptom is occurring in both engines points to the "possibility" that stray voltage or a near miss lightning strike might have damaged both ECM's.

 

[captadamr]

Re: Merc 4 stroke 115hp problems

thanks,

I appreciate all the help you have given me. If your ever in my part of the world i'll buy you a few. I will have to jump all over my mechanic to get to work on the boat, Ive fixed all the things that needed to be, so i have a boat with all systems go except motors

 

[Bigjohn1]

Re: Merc 4 stroke 115hp problems

No problem and glad to help. I feel your pain regarding living in a remote area with limited support - been there, done that. If you don?t mind, please report back after the repair so we can all learn what happened and the root cause.

 

[captadamr]

Re: Merc 4 stroke 115hp problems

So here it goes:

Worked on the motor til 8:30, and after 3 test runs got it all sorted.
1. ECM was finished on port motor, but now the tach works and its running great
2. Stbd Motor, burnt #3 plug, Plugged in the light, and it said Shift position sensor, found out someone didnt put a pin in that allowed the asselbly to slip.
Took on final test run, and got 4800rpm with the Aluminuim props.

Thanks for your help bigjohn

 

[Bigjohn1]

Re: Merc 4 stroke 115hp problems

I'm glad it all got sorted. The shift position sensor and crank position sensor are both down the column in the troubleshooting procedure AFTER the other checks are all done. I feel bad now that I never mentioned them but the troubleshooting sequence said to do the other checks first to eliminate them.

On your props and the current rpm - your actual redline rpm is 6250 (at which time the ECM begins to shut down cylinders to save your motor). The redline WOT figure Mercury says to use is 6,000rpm where props are concerned. This means you really ought to think about changing props soon if you are confident the motors are back restored to full working order.

Assuming the engines are now good, the perfect prop for you would be Stiletto Bay Pro I in 13 pitch. I still have some misgivings about the fact that you are only getting 4,800 rpm with 15 pitch props (even though they are the el cheapo Black Max units in 15 pitch). I would think even Mercury's low end props (in 15 pitch) would be getting you in the mid 5,000 rpm range. If your tach is accurate and the motors completely check out good, you should not continue to run the current props becuase you are lugging the engine. Mercury made these engines with a high forward gear ratio and most people who run them with heavy loads need to run 13-15 pitch props. I personally run a 17P Trophy Plus but I am only getting around 5,600 WOT rpm's so I should buy a new prop myself.

 

[captadamr]

Re: Merc 4 stroke 115hp problems

We made a run today to a calm bay to do some knee-boarding, everything was fine, ran to the beach, ran @ 4000rpms into a 3ft chop, all was good. On the way home with my brother, we got it up to 5000rpms but there is limited uptrim, before they begin to slip. That was with 100gal of fuel on board.

The only issue is during idle the #4 injector is not spraying or, that the plug isnt getting juice, once over 1500rpms the engine runs fine, just below that rpm it runs rough.The spark plug is fine. I am thinking its the coil or plug wire not delivering the spark @ the low rmp. Makes any sense?? It only happens when it gets warm, can the being at OTemp, cause the coil to not spark effectivly??

Would the stainless 4blades allow to uptrim higher, as well as allow them to spin up. The dealer was showing me some honda 4-blade, but i dont remember the pitch.

thanks
adam

 

[Bigjohn1]

Re: Merc 4 stroke 115hp problems

Without question, a 4-blade stainless prop will allow the engines to "bite" the water MUCH better with less prop slippage. Honda makes fine outboards but I have no personal experience with what props they manufacture. You are using a boat with engines geared rather high and will require a speciality prop for best performance. If Mercury made a Trophy Plus 4-blade prop in 15 pitch, that would likely be the perfect prop but alas, the lowest pitch they make is 17 (the one I am currently using).

The Bay Pro I by Stiletto is a 4-blade ss unit and is made in both 13 and 15 pitch sizes. I feel this prop is likely the closest thing to perfect either of us is going to come.