Loses power at 5000 rpms

[TnTommy]

2000 evinrude 50hp 4stroke after engine gets hot when I get up to 5000 rpms or higher about three min I lose power and rpms drop to around 2500 to 3000, I can run it at 4500rpms and it runs fine ,and when I throttle down to around 2500 to 3000rpms for a min I can throttle back up and is ok untill I hit 5000 rpms or more for more than a few min. Is it a fuel problem?
View attachment VID_20260617_142203294.mp4

 

[Crosbyman]

fuel burn is always hot it is not the cause. Lack of proper cooling water circulating inside the powerhead to draw out the heat allows it to build up so check impeller, thermostat, internal cooling channel obtruction (sediments).

POST your mdl#

 

[TnTommy]

E50PL4SS

 

[Crosbyman]

here is one answer from an AI source...
If your E50PL4SSC is a year 2000 Evinrude/Johnson 50 HP 4-stroke, and it overheats mainly at higher RPM, I would check these items in this order:

1. Water pump impeller and housing
   • Most common cause.
   • Even if the telltale stream looks good, the pump may not deliver enough volume under load.
2. Thermostat stuck partially closed
   • Very common on older engines.
   • Remove and test in hot water with a thermometer.
   • A thermostat that opens late can cause overheating at speed.
3. Blocked cooling passages
   • Sand, mud, corrosion, or mineral deposits in the cylinder head or water jacket.
   • More likely on a 26-year-old motor.
4. Pressure relief valve (if equipped)
   • If stuck, cooling flow at higher RPM can be restricted.
5. Weak telltale but normal at idle
   • Check for debris in the telltale hose and outlet.
   • A strong telltale does not always mean adequate block cooling.
6. Temperature switch or wiring fault
   • Verify actual engine temperature with an infrared thermometer before assuming a true overheat.

 

[saltchuckmatt]

Could be that SPECIAL sweet tea...none of that funny stuff in there I hope! Lol....

Get an IR gun and shoot the temp at where the head meets the block. Also shoot around the T-stat area.

Blockage, bad impeller, T-stat, and overheat sensor are all suspect.

Pretty sure that's made by Suzuki.

 

[Crosbyman]

SPECIAL sweet tea ??

 

[TnTommy]

It is made by Suzuki, the over heat alarm never went off, should it have?

 

[saltchuckmatt]

It is made by Suzuki, the over heat alarm never went off, should it have?

Back of the head....sensor coming off the top and typically a tan wire.

Usually there is a rubber cover you slide off to revel a knife connector...I stab a pick in there and ground it to a clean ground. With the key on the alarm horn should blair.

Sender or horn...I find the horn fails the most.

 

[jimmbo]

There is a slight chance it is a Fuel Problem if the Boat has a Built in Fuel tank, and the Tank Vent is restricted, partially plugged. Verify the Overheat Sensor and Horn/Light are working first though

 

[TnTommy]

Both my temp sensor have a black and purple wire going to them

 

[jlh3rd]

if your sensor/horn is working, then there should be an overheat warning.
If it's not overheating:
then I'd jump to a fuel issue as jimmbo states. So...
Don't know your history of ownership, so responding likewise and based on my recent experience with my new 2021 re-power Merc 115 on my pontoon.
I developed a similar experience last year.
What color is your fuel line?

 

[TnTommy]

So I replaced all fuel filters and fuel line before season this year , the line coming from tank was grey

 

[TnTommy]

Ok so just looking around I'm finding little metal shavings all over Stb side of motor they look like there coming from where the starter meets the flywheel the teeth on both look worn and shiny , could this have anything to do with it or just another problem?

 

[Scott Danforth]

that is another problem. appears to be parts of the ring gear teeth being shaved off by the starter bendix and hitting the magnet

looks like your bendix may not be tossing fully. could be bad ground connection at the motor.

 

[racerone]

Test run with another fuel tank ?

 

[jlh3rd]

So I replaced all fuel filters and fuel line before season this year , the line coming from tank was grey

yep
The grey line appears to have been my issue. There's a story.
Your fuel line is the black one now?

 

[TnTommy]

Yes all new black lines including the primer bulb line