Evinrude 90HP won’t go over 2000RPM

[Cameron119]

Evening everyone. Short back story. Had my 90 evinrude (E90eleuc) serviced last year was purring like a kitten. We were out tubing and all of a sudden after going in neutral to switch riders we can only go 2000rpm. I noticed one of the sides of the engine feels very hot to the touch, the other side is good.

Things I’ve checked
-throttle response seems fine, at full throttle the RPM is limited.
-spark is good on all 4 cylinders.
-Disconnected the thermostat wires and ran engine, same problem.
-removed the thermostat on the hot side put in bowl with boiling water and it opened. Cool water closed it.

I’ve read something about a neutral switch is that inside the actual OEM throttle beside the seat?

Any suggestions would be great

 

[jimmbo]

All the Cylinders getting fuel? If not, they aren't getting Oil. What do the Plugs look like?
As for Good Spark, is it good enough to jump a 3/8" gap?
Have you tested the Compression?

 

[Cameron119]

When I pulled the plugs they were only slightly discoloured and had a very light brown coating, not hard carbon. We tested all 4 plugs one at a time and looked for spark and it looked good, the plug gap seemed quite wide, I’d say around 3/8.

As far as compression I won’t be able to check until I get back home on Monday.

 

[Berdink]

When I pulled the plugs ...clip... the plug gap seemed quite wide, I’d say around 3/8.

Are you saying the plugs had a gap of around 3/8?
Or that you used an adjustable spark tester and the spark jumped the 3/8 gap on the spark tester?

 

[Cameron119]

Roughly 3/8” gap. I did not use a spark tester we pulled the plug and re attached the wire with it grounded on the power head to test spark.

 

[saltchuckmatt]

You said one side was hot...old school method, warmed up and fast idling...touch the top of the head where it meets the block, it should not be scalding. Port a few degrees cooler but not noticable to the human hand. Port side head have a two wire sensor? Tan wire and a white wire? Could be "slow mode"

 

[jimmbo]

Roughly 3/8” gap. I did not use a spark tester we pulled the plug and re attached the wire with it grounded on the power head to test spark.

What was approx 3/8" gap? A regular spark plug has a gap of 0.030", 3/8" is 0.375", almost 13 times wider

 

[Cameron119]

You said one side was hot...old school method, warmed up and fast idling...touch the top of the head where it meets the block, it should not be scalding. Port a few degrees cooler but not noticable to the human hand. Port side head have a two wire sensor? Tan wire and a white wire? Could be "slow mode"

So it was on the driver side (port) where there is only one wire(tan) and that side was nearly scalding to the touch while the other side was just warm.

I’m not worried about the spark plug gaps because the engine was running perfect for days then suddenly stuck at 2000rpm. I find it hard to believe the plug gap would be the issue.

How do I get the motor out of SLOW mode?

 

[jimmbo]

A 3/8" Gap is for testing the Ignition System's capacity to supply a Spark strong enough to jump a gap of 0.030" when the Spark Plug is subjected to the Conditions inside the Combustion Chamber on the Compression Stroke

Something has happened to cause a loss of more than 50% of the Engine's Rpm at WOT. Loss of Spark to at least one of the cylinders can do that, as can other things. Some diagnostics are in order

 

[racerone]

Install a new water pump impeller.----The 3/8" spark jump test has nothing to do with the gap on the plugs.----It is a standard method to check ignition maximum / proper spark intensity!

 

[Cameron119]

A 3/8" Gap is for testing the Ignition System's capacity to supply a Spark strong enough to jump a gap of 0.030" when the Spark Plug is subjected to the Conditions inside the Combustion Chamber on the Compression Stroke

Something has happened to cause a loss of more than 50% of the Engine's Rpm at WOT. Loss of Spark to at least one of the cylinders can do that, as can other things. Some diagnostics are in order

Ok perfect this is one thing I will take a look at when I get back home. Does anyone know where I can download a copy of the service maintenance manual for this motor?

 

[Cameron119]

Install a new water pump impeller.----The 3/8" spark jump test has nothing to do with the gap on the plugs.----It is a standard method to check ignition maximum / proper spark intensity!

I will try the impeller. From what I remember I will need to drop the lower unit for this.

 

[Berdink]

... clip.... Does anyone know where I can download a copy of the service maintenance manual for this motor?

I tried searching for an electronic copy for my 1994 90hp Johnson.
I never found one, and I didn't want to pay for a subscription one.
I ended up buying a used physical one on eBay.

 

[Crosbyman]

your mdl# E90ELEUC should be a 1997 not a 1994

https://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1997&hp=90&model=E90ELEUC

this place had easy PDF downloadable books and I have used it for the Johnson Evinrude oldies manual .... 450 pages 20$$

1997 Evinrude 90HP-175HP 507268 Outboard Service Manual

1997 Evinrude 90 HP thru 175 HP 4/6 Cylinder 60° Loop V Outboard Motor Service and Repair Manual # 507268 covers 90HP 105HP 115HP 150HP 150HP 175HP .pdf download

watercraftmanuals.com

 

[jimmbo]

That is a completely different engine, than what a 1994 engine would be.

 

[Crosbyman]

so is it a 94 or a 97 for my info ?

 

[racerone]

The ----EU----makes it a 1997 model.

 

[Cameron119]

Hey guys just a thought I didn’t have time to do all that troubleshooting you guys suggested yet, but I remember just before it happend I asked my daughter to put the boat into neutral from a slow forward and I think she did it without depressing the red grip switch on the shifter. Could that in any way cause an issue related to what I stated above?

 

[saltchuckmatt]

Hey guys just a thought I didn’t have time to do all that troubleshooting you guys suggested yet, but I remember just before it happend I asked my daughter to put the boat into neutral from a slow forward and I think she did it without depressing the red grip switch on the shifter. Could that in any way cause an issue related to what I stated above?

You only need to pull up on the red handle to get it "out" of neutral....not in.

 

[Berdink]

Hey guys just a thought I didn’t have time to do all that troubleshooting you guys suggested yet, but I remember just before it happend I asked my daughter to put the boat into neutral from a slow forward and I think she did it without depressing the red grip switch on the shifter. Could that in any way cause an issue related to what I stated above?

Yep, time is limited.
If you could though, if you find the solution to the issue, please post what you figured out.
It makes it helpful for others with similar issues.
Thanks