2013 Suzuki 150 HP Outboard, intermittent degrade in power

[TraceR]

Engine starts fine. Full throttle and I'm up and cruising 30 mph at 5000 RPM. I don't touch anything, and RPM reduces to 2800-3000 and we're plowing along at 10 MPH. I turn off the motor, let it set for 3-5 seconds, and restart it. I'm back up on plane in a matter of seconds and running smoothly, then it repeats itself. I can go anywhere from 2 minutes to 30 minutes in between getting bogged down.
Took it to the shop, the replaced all filters throughout, replaced spark plugs and spark plug wires. And since it was later in the season, I had them change all the fluids also.
Any idea what could be causing the motor to bog down like this?

[Moonlighter]

Did they connect it up to SDS and check for codes?

[TraceR]

Yes they did. No codes came up.

[Moonlighter]

First thing to do is to get the Boats electrical system into tip top condition because these engines are very sensitive to voltage. They do weird stuff including possibly the sorts of things yours is doing if they dont get it. All of this you can do yourself and it should be part of your regular maintenance program too.

So

Check the battery - load test if possible, any doubts, replace it with new one that meets specs for your engine.
Undo, clean and then tighten main battery connections.
check condition of main battery cables for internal corrosion
find the white wire connection (most often at the main battery switch +) undo it, clean, check the fuse and fuse holder for corrosion.
Chexk the connections behind your main switch, clean and tighten.

see how that goes.

[TraceR]

Thanks for the input. I pulled the battery's and had them checked. One was bad, so had it replaced. But it wasn't the one that I was using at the time, so that was kind of odd. I;ve done all the checks and cleaning too. So ran it 4 times over last 2 days and it ran much better, but on 2 of those occasions, it bogged down for 3-4 seconds, and then went back up to 5000 RPM. It's a ton better, but these 2 incidences have me concerned it's still not 100%. Any other advice?
Thank you very much in advance.

[frogbite]

You may still have a fuel flow issue on top of possible electrical issues. When it bogs down can you pump the primer bulb and get it climb back up? Is the primer bulb collapsing when it happens? If it was all the time I would suggest running from another fuel source such as a portable tank to eliminate the primer bulb and and anti-siphon valve on the gas tank.

[TraceR]

I'll have it out tomorrow. I'll check primer ball next time.

Thanks.

[TraceR]

Had it out today and it ran great, until it didn't. Ran 5 miles with no issues, then it sat for 3 hours while I fished, then started it up and it bogged its way back to the dock all the way. Worst it's ever run. The primer ball did not collapse, and I did not try to pump it as I forgot this was one thing you wanted me to do. Sorry for that. I'll do it next time. Then I picked up my father in law and it was turned off for about 5 minutes while I waited for him to get there. Ran great down to the fishing hole with no issues. Fished for an hour, then we had it idling for about 15 minutes as we checked crab pots. Loaded everything up and we headed back to the dock where it bogged down once again about half way home. Turned it off, waited 10 seconds, and it was still bogged down. Turned it off for another 10 seconds and started it up and ran all the way home with no issues. Every time it bogged down, we looked at the primer ball and it was not flat.
Could this be a computer issue with it sensing something and it goes into protect mode? Then out of it when the sensor realizes everything is ok? Not sure why it runs perfectly, or near perfect, once I turn it off. Is it because the sensor/computer resets itself? My father in law thought vapor lock, but is not sure.
Once again, any advice is greatly appreciated.

[Moonlighter]

Did you check that white wire THOROUGHLY? And the fuse in it?? And the fuse holder and wires to/from it?

Any indication at all of corrosion in that wire or its connections means problems.

Also have another close look ath the main battery cables. If they have developed internal corrosion this will also cause issues.

It seems possible to me that your original work on the electricals improved things, so the problem could still be in those electrical componnets and warrants further investigation there.

A wire with corrosion internally has higher resistance and gets hot, which further increases resistance. Turn off, it cools, runs Ok again for a while?? Maybe something like that.

[frogbite]

It sounds like to me that it did not per his last experience. That white wire can be such a pain. Still could be fuel flow as well.

[Moonlighter]

It sounds like to me that it did not per his last experience. That white wire can be such a pain. Still could be fuel flow as well.

I agree.

Next would be to check fuel pressure under running conditions.

[TraceR]

I thought I had checked the right wire, but I was incorrect. The white wire/fuse was hidden behind one of the batteries, my bad. So the fuse was fine, but the fuse box was corroded really bad. The local Suzuki dealer is closed over the holiday so I couldnt get a new one. So I cleaned it as best I could. I didnt have much hope seeing as bad the corrosion was. Took it out yesterday and it still bogged down. I'm going to take the boat to the dealer Tuesday morning and have them replace the white wire completely. I'll report back after that.

If there is anything else I should get done while at the dealer, please let me know. I'll have them do a thorough check on the other electrical components. IMG_9844.jpg

[Moonlighter]

I thought I had checked the right wire, but I was incorrect. The white wire/fuse was hidden behind one of the batteries, my bad. So the fuse was fine, but the fuse box was corroded really bad. The local Suzuki dealer is closed over the holiday so I couldnt get a new one. So I cleaned it as best I could. I didnt have much hope seeing as bad the corrosion was. Took it out yesterday and it still bogged down. I'm going to take the boat to the dealer Tuesday morning and have them replace the white wire completely. I'll report back after that.

If there is anything else I should get done while at the dealer, please let me know. I'll have them do a thorough check on the other electrical components. IMG_9844.jpg

Yikes that certainly doesnt look good!

Get it fixed and see how things work afterwards. Of course it might not be the cause if the issues, but it certainly is worth fixing!

Fingers crossed!

[TraceR]

Ok, brought the boat into the mechanic today and showed him the picture. He changed that part out, along with part of the white wire that he found corroded. He stated the wire fuse holder showed signs of corrossion and replaced that too. He also took apart the fuel pump and cleaned a screen that is the size of your pinky fingernail. He also changed the fuel line from the bulb to the engine. He test drove 2 miles w no issues. Called me to come test drive longer, which I did. After about 3 miles, the engine bogged down again! Only for 3-4 seconds, then back up. Then I idled and went slow (3-4 miles/hour) for about 10 minutes, then I noticed the engine go from 1800 rpm to 1500 rpm (bad news), so I got my video out and recorded me gunning it and it only going up to 3800 rpm and not planning out. I then shut it down and waited 10 seconds, restarted it, and it ran perfectly all the way back to the boat launch.
Mechanic wants me to run gas from my 6 gallon tank straight to engine to see if it does the same thing. I"ll probably get to it early next week.

Any other suggestions?

[Moonlighter]

Earlier you said that you changed all the fuel filters... did that include the metal high pressure filter?

This one, or equivalent on your model?

https://www.boats.net/product/suzuki...06b267aec7cf46