Help -1991 115 power loss / bogging down

[The Adventure Pak]

Thank you all in advance for the help on this.

My 1991 115 has been a great motor up until a week ago. I took it out on a Friday night and had no issues. Went out again Saturday morning and she had lost all power. At WOT, I could only get up to about 5mph on my 1991 Nitro 180FS and so the work began. It definitely felt like a fuel starvation issue.

To this point I have completed the following:
-Thoroughly cleaned the carbs - the floats seem to be working just fine, all jets are clear.
-Replaced the fuel lines under the hood
-Replaced the VRO pump with a Non-VRO Fuel Pump (through the guidance of my local shop)
-Replaced all 4 plugs (they all look good and show normal coloring)


Prior to replacing the VRO Pump, I bought a rebuild kit and rebuilt it. It almost seemed to work at idle, but would only run for about 2 min before it died. I could run it just fine as long as somebody was pumping the primer bulb.

I replaced the fuel pump tonight and took it out to the lake. She cranks right up and idles just fine. When I put the throttle into byp*** mode, I can rev it to the moon and it has no issues, doesn't lag, sputter, just runs out fine. But, as soon as you put it in gear, it bogs down and just won't go. I took a quick video and put it at this link: https://youtu.be/mcfbS9zP5j8

Does anyone have some ideas on what I can do next?

Thanks!!

Jeremy

[Joe Reeves]

The engine ran fine on a Friday night... you docked, tied it up, or trailed it home with no problems? Then, hours later, as soon as you put it into gear, it bogs?

Did you or anyone else remove the hood of that engine for any purpose before you walked away from it for that Friday night?

NOTE that a 4 cylinder engine, in neutral, running on two cylinders, will race away rather nicely... BUT... beware that there is no such thing as a "throttle bypa$$ mode... racing any outboard in neutral is risking a runaway engine whereas it turns into a diesel increasing its rpms by the second. Turning the key OFF, closing the throttle, or even yanking the spark plug wires off amounts to nothing... a runaway will stop only when it explodes, runs out of fuel, or has it's fuel/air supply clogged with rags or whatever. Usually it stops by getting rid of its connecting rods. Something to keep in mind.

Did the linkage between the throttle arm and the timer base under the flywheel pop off? If so, it's running in a full retard timing position.

Are all throttle butterflies wide open at the full throttle position... fully closed at the idle position?

Going by your tachometer reading... was/is the idle rpm lower now (Sat) than it was the night before (Fri)? What is the idle rpm (now) as compared to it's normal idle rpm?

Standing in back of the engine, facing the spark plugs, the cylinders are numbered as follows:

2.....1
4.....3

With all spark plugs removed, check the compression. What is the psi reading of all individual cylinders as numbered above.

Spark Test: Still, with all s/plugs removed... using a spark tester whereas you can set a 7/16" gap, the spark should jump that air gap with a strong wide blue lightning like flame... a real SNAP! Does it? Note that the 7/16" air gap is important.

Let us know what you find.

[The Adventure Pak]

Joe Reeves Thank you for the quick and indepth response. I added my answers below:


The engine ran fine on a Friday night... you docked, tied it up, or trailed it home with no problems?Yes sir. She cranked on the 1st attempt, ran out just like normal and got home as per the usual. I didn't notice anything out of the ordinary. Then, hours later, as soon as you put it into gear, it bogs? Yes. When I put in on Saturday, there were a lot of waves coming into the ramp, but I didn't feel anything hit the motor, trailer, etc. It did struggle a bit to start, took 5 attempts or so, but then ran out fine, except for being very low on power.

Did you or anyone else remove the hood of that engine for any purpose before you walked away from it for that Friday night? Negative

NOTE that a 4 cylinder engine, in neutral, running on two cylinders, will race away rather nicely... BUT... beware that there is no such thing as a "throttle bypa$$ mode... racing any outboard in neutral is risking a runaway engine whereas it turns into a diesel increasing its rpms by the second. Turning the key OFF, closing the throttle, or even yanking the spark plug wires off amounts to nothing... a runaway will stop only when it explodes, runs out of fuel, or has it's fuel/air supply clogged with rags or whatever. Usually it stops by getting rid of its connecting rods. Something to keep in mind. Gotcha. Thanks for the education. This is my 1st 2-stroke outboard and I didn't know that.

Did the linkage between the throttle arm and the timer base under the flywheel pop off? If so, it's running in a full retard timing position. Negative. The throttle and shift linkages all appear intact as they should be.

Are all throttle butterflies wide open at the full throttle position... fully closed at the idle position? Yes. Before I took the carbs off and cleaned them, I did run it with the air box off. All the butterflies opened and closed correctly. And, the linkage between the carbs is attached properly.

Going by your tachometer reading... was/is the idle rpm lower now (Sat) than it was the night before (Fri)? What is the idle rpm (now) as compared to it's normal idle rpm? Well, my tach doesn't work. I know...shame on me I have not heard a noticeable difference at idle RPM. It sounds normal to me. I took a short video of it at idle tonight. https://youtu.be/6kXn-AnCDWI It is not perfectly smooth, but this is about as smooth as it has ever been. I should note that this is my 3rd season with the boat and the power head was replaced 2 weeks before I bought it. I have probably put 150-175 hours on it since I have had it.

Standing in back of the engine, facing the spark plugs, the cylinders are numbered as follows:

2.....1
4.....3

With all spark plugs removed, check the compression. What is the psi reading of all individual cylinders as numbered above. 95, 100, 100, 100 in 2, 1, 4, 3 order.

Spark Test: Still, with all s/plugs removed... using a spark tester whereas you can set a 7/16" gap, the spark should jump that air gap with a strong wide blue lightning like flame... a real SNAP! Does it? Note that the 7/16" air gap is important. I need to pick up a spark tester. Off to the auto parts store I go!!!!


Thanks again!!

[Joe Reeves]

The spark tester.... this may be of interest if you're planing on staying in boating.
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(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4

This can obviously be modified to a 6 or 8 cylinder setup tester.
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The tachometer being faulty could lead to other problems, one of which (loss of power) you may have just encountered, as follows.
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(Testing Tachometer With Water Cooled Regulator/Rectifier)
(J. Reeves)

A quick check is to simply plug in a another new tachometer as a piece of test equipment. If the new tach works properly and the old tach didn't, obviously the old tach is faulty.... but usually boaters don't carry around a spare tach (see below).

A faulty rectifier wouldn't damage the tachometer, the tachometer simply wouldn't work. This is due to the fact that the tachometer operates off of the charging system and the rectifier converts AC voltage to DC voltage, enabling the charging system. A faulty rectifier disables the charging system, and the tachometer simply doesn't register.

However.... those water cooled regulator/rectifiers that are used on the 35 ampere charging systems (and some others) bring into play a different type problem, and as you've probably found out, they are really a pain to troubleshoot via the proper procedure. There's an easier way.

The tachometer sending/receiving setup operates off of the gray wire at the tachometer. That same gray wire exists at the engine wiring harness which is connected to the engine electrical terminal strip. You'll see that there is a gray wire leading from the regulator/rectifier to that terminal strip, and that there is another gray wire attached to it. That other gray wire is the wire leading to the tachometer which is the one you're looking for.

NOTE: For the later models that DO NOT incorporate a wiring terminal strip, splicing into the "Yellow Wire" mentioned will be necessary.

Normally the Gray wire leading from the tachometer is attached at the terminal strip to another Gray wire which leads from the water cooled voltage regulator/rectifier...... remove the gray wire that leads to the tachometer. Now, find the two (2) yellow wires leading from the stator to that terminal strip. Hopefully one of them is either yellow/gray or is connected to a yellow/gray wire at the terminal strip. If so, connect the gray wire you removed previously to that yellow/gray terminal. Start the engine and check the tachometers operation, and if the tachometer operates as it should, then the regulator/rectifier is faulty and will require replacing. If the tachometer is still faulty, replace the tachometer.

If neither of the yellow wires from the stator is yellow/gray, and neither is attached to a yellow/gray wire, then attach that gray tachometer wire to either yellow stator wire, then the other yellow wire, checking the tachometer operation on both connections.

I've found this method to be a quick and efficient way of finding out which component is faulty.... the tachometer or the regulator/rectifier. It sounds drawn out but really only takes a very short time to run through. If the water cooled regulator/rectifier proves to be faulty, don't put off replacing it as they have been known to catch on fire with disastrous consequences.
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Compression = That's very good, just 5 psi difference on #2 cylinder.... However, although you said "replaced" powerhead, you did not say "rebuilt" or "new" powerhead. If rebuilt, it is odd for a engine to show a difference between cylinders even though 5 psi is normally nothing to be upset about. However, check that compression occasionally for radically changes. Differences like that are usually contributed to a carburetor jet becoming slightly clogged, fouled, gummed.
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I appreciate the manner in which you answered my questions. Many boaters reply with answers that are confusing generalities such as some women (and politicians) that talk for hours and say nothing.
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Frankly, you have pretty well covered all the bases excepting the spark test and I will await that. Even if at the launch site, water had managed to enter the engine via a exhaust port (wave breaking over the hood), it would have worked its way out over a days outing. At the present, that leaves me with the thought that since the voltage regulator/rectifier is apparently faulty (tach not working), battery charging voltage would not be going where it belongs but would rather be backing up at the stator which would add to the overheating it faces continually which in turn would result in what we call a meltdown of the stator. A meltdown can be seen easily, visually,... just look closely under the flywheel for a sticky looking substance to be dripping down from the stator upon the timer-base and powerhead area. <-- Look closely for this meltdown scenario as boaters have sworn that this had affected their engine's ignition system.

A reminder.... Use the recommended Champion spark plugs.

Let us know what you find.

[The Adventure Pak]

Ok, Joe Reeves Thanks for all your help! I am beyond my scope of knowledge so learning through this is great. Bummer is I'm not fishing lol.

Back to business. I picked up a spark tester and per the mfg instructions on the package I did one cylinder at a time with the spark plugs in. Long story short, each cylinder tested out well, fired right up and had good spark.

One thing I noticed is that idle rpms were a tad higher while doing this test. Not sure if that is coincidence or yet another symptom to chase down.

Regarding the tach, it is new, just not hooked up. I am learning a good lesson that I should have taken the time to complete the task when I installed the new gauges. I got the speedo and water pressure all good. Trim and Tach not so much. Guess what I'll be doing tomorrow night? Yup, you got it...completing the gauge wiring.

Oh, I also took some time and inspected around the motor looking for any signs of abnormality like the melting or sticky substance that you mention above. To me, this motor is very clean and I don't see anything that looks wrong.

Last thing, so as not to babble on like a woman, or politician or worse a woman politician...the plugs are brand new Champions. At least I am doing one thing right!

Thanks
Jeremy

[Joe Reeves]

Originally posted by The Adventure Pak View Post

Ok, Joe Reeves

1 - I picked up a spark tester and per the mfg instructions on the package I did one cylinder at a time with the spark plugs in. Long story short, each cylinder tested out well, fired right up and had good spark.

2 - One thing I noticed is that idle rpms were a tad higher while doing this test. Not sure if that is coincidence or yet another symptom to chase down.

3 - Oh, I also took some time and inspected around the motor looking for any signs of abnormality like the melting or sticky substance that you mention above. To me, this motor is very clean and I don't see anything that looks wrong.Jeremy

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1 - Is that spark tester one whereas a 7/16" gap can be set? "Good Spark" is a generality... we need to know if the spark is actually jumping a 7/16" air gap with a strong blue lightning like flame... a real SNAP!

1 - "Fired Up"? Are you having that engine running while doing the spark test? If so, that's a no no. Spark test is to be done at cranking speed. Spark plugs are to be out so as to obtain the highest cranking speed.

2 - "rpms a tad higher"... Yeah, sounds like you're running the engine.

3 - The meltdown scenario of the stator (under the flywheel)... this is not a case of "if", it is a case of "when" as that flywheel area runs hot enough normally to take the skin off your hand. The two coils that throw approximately 300 AC volts to the powerpack capacitor, needed to energize the pack, are located within the stator... one at the immediate front of the stator, the other at the immediate rear portion. When they fail, the stator will crack slightly, and that sticky looking stuff that drips down on the timer base and powerhead is a dead giveaway of a power loss to come... hence my harping on it. Don't just glance at that area... get out your flashlight and look at it closely.

I'm leaning on not overlooking anything pertaining to the stator dripping scenario due to the fact that the engine ran fine at shutdown time, then a few hours later... immediate problems! At "shutdown time", the water drains down out of the powerhead and all of the heat rises to the flywheel area that contains the stator, adding to the present heat... and this is the manner in which it finally fails. It may be in new condition... I just want to be sure of it.
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(Drop Test)
To obtain a general idea of the engine's performance at a idle rpm, do a drop test... engine running... with insulated pliers, remove the spark plug boot from each spark plug, one at a time. The drop in rpm should be the same on all cylinders. Is it?

[The Adventure Pak]

Joe Reeves Thank you again for all of your help! At this point, I have given in and taken the boat to the shop. I am out of town for a bit, so I don't have the time to work on it, but I need it back. So, I went ahead and dropped it off.

Will be curious to see what he says!!

Jeremy