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2005 Yamaha F150 surges at 2500 rpms

210ChaosOwner

210ChaosOwner

Participating Member
State
NJ
Hello, has anyone experienced a surge at around 2500 rpms?

Took the boat out for the 1st time and it runs great until I get up over 2500 rpms, actually runs ok for a bit then starts dropping rpms and then increases again. If I back down below 2000 it runs perfect.

Any suggestions? Thank you.
 
Had a similar issue last year on a 135 volvo i/o. Have your water impeller checked. Could be a “limp home” mode because of bad impeller so low rpm is ok but not high.
unfortunately I repaired then immediately sold the boat.
 
  1. Check and clean all the engine and other grounds. Make sure all battery and battery switch connections, are clean and secure and advise installing lock washers on battery switch connections.
  2. Check the resistance on all the plug wires, if any are over 10 ohms, replace.
  3. Check / Drain off or replace the Fuel water separator.
  4. Check all the connections on the fuel line including the bulb for leaks
  5. Put some Startron into the fuel take to help move the water off of the bottom of it.
Something (usually simple) is starving the engine for fuel / causing a cylinder off to drop under load once the engine is at FOT (Full Operational Temp)

Let us know which of the 5 (or other item) corrected the condition.

Dave
 
So appears no water in the fuel, added Startron to the fuel anyway but my battery cables were very loose....tightened them up. Once the weather clears we'll give her another sea trial. I bet it was those battery cables. We'll see. Thanks Dave.
 
The one time my Yamaha 4s went into limp mode it was due to one of the wires for the tilt/trim getting chaffed and grounding near the binnacle. Shortly after it started happening I would start blowing fuses when trying to tilt the engine and that revealed the problem. Not that this is what’s happening in your situation, but I’m just putting one of my lessons learned out there since it’s related.
 
Most Welcome!
Voltage drop for any engine that is controlled via a ECU (which most are) can create all kinds of Havoc and strange operational issues... Once they get below 10.5 VDC, they simply cannot operate and make the needed engine adjustments no matter if it is a Yamaha or a Porsche for that matter ;)

Another good read on the subject which is why I made mention of it on #1 above...

https://www.performanceoutdoors.net/threads/sudden-power-lost.6837/

Keep up in the loop on this one :cool:
 
Yes Sir, this was the level at idle. Low? Normal?

My battery cables were loose, quite a bit, Tighten them and changed the spark plugs and filters. Changed the bulb. Checked all other connections.

Test run coming on Tuesday.
 
At idle that might provide plenty of fuel, if it was not enough (naturally) she would stumble and die.

Might be helpful to either replace it and or drain it off and reinstall. Who knows how long that one has been in place, even though (pending the type) it is as much of a water is present sensor, than a actual filter.
 
Then it should be fine, the engine is simply not developing a lot of fuel pressure at idle and doubt that filter is ever totally full and suspect it has a lot of turbulence as the fuel is going through it as it is... ;)
 
Had the same problem last year with my Suzuki 4 stroke. Spoke with a mechanic and he said to change the spark plugs, so I did and it ran normal again.
 
Ok Folks, here's the update. I did what Dave said (above checklist) except check the ohms everywhere. The filters I replaced were new but I replaced them anyway. I also replaced the spark plugs, taking out new ones as well. The most glaring problem of all was that my battery cables were quite loose. I tightened them all, check all other connections, they were good. I replaced the bulb and added Startron.

Yesterday we took her for a nice ride and she ran beautifully. Such a great feeling. I believe it was as simple as the battery cables being loose.

Dave, thank you!!! and thank you to this forum for again helping me. Beers are on me!!!
 
Last edited:
210ChaosOwner said:
Ok Folks, here's the update. I did what Dave said (above checklist) except check the ohms everywhere. The filters I replaced were new but I replaced them anyway. I also replaced the spark plugs, taking out new ones as well. The most glaring problem of all was that my battery cables were quite loose. I tightened them all, check all other connections, they were good. I replaced the bulb and added Startron.

Yesterday we took her for a nice ride and she ran beautifully. Such a great feeling. I believe it was as simple as the battery cables being loose.

Dave, thank you!!! and thank you to this forum for again helping me. Beers are on me!!!
Click to expand...
Awesome, and Most Welcome! Glad that the KISS system worked again ;)

Voltage drops are always an issue with Computer controller (anything) much less engines. And the Marine environment much the the pounding, makes that an even greater possibility and needs attention and solid PM (Preventative Maintenance) to help keep such issues in check.

Another reason why I run high quality Odyssey Batteries and keep them charged so not only does it start when I put the Key to it, but keeps running no matter the Sea States. Trust me, the loss of power in heavy seas thus getting all "sick and and sideways on a wave" can be a killer :oops:

Enjoy!
Dave
 
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