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1990 Evinrude 25HP - Stutter / Pulsing / Spud

M

mdoraty

New member
Hi All-

I have a 1990 Evinrude 25hp(E25ELES). It seems to be stuttering / pulsing / spudding. I am posting some videos of the stuttering / pulsing. I haven't been able to get anything recorded on the spudding quite yet but its been about a week since I've seen that behavior.

What I have done:
--carb rebuild at Carb Rebuild local shop
--new Fuel pump
--new spark plugs
--new spark plug wires
--new internal fuel lines
--new fuel tank
--new fuel hose/primer bulb

What I’m planning on doing next in the near future:
--compression test
--replace lower gear unit oil
--replace water pump impeller

Videos Below:
[video]https://sidecargps.blob.core.windows.net/transfer/video-1625025548.mp4[/video]
[video]https://sidecargps.blob.core.windows.net/transfer/video-1625025584.mp4[/video]


I'll make updates once I complete the other items on my to-do list. If anyone has any ideas/suggestions before then please let me know.

Thank you for your time,
Mitch
 
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Hi All,

I forgot to mention that the issues only seem to occur once the engine is warmed up. Running it WOT for 60-90 seconds.
 
What happens when you pump the primer ball? Have you checked for spark when that happens? Do a link and sync and get the idle lower before you wreck the lower unit.
 
I was able to do compression test today.

Tested each cylinder twice
Top-- 110/108
Bottom-- 105/106

flyingscott - Pumping the primer ball seems to have no effect once in that state. I have not checked for spark when it happens but have checked that spark is there when I installed the spark plugs. I will try checking for spark this weekend once/if it goes back into this state.

racerone - It could be. I checked the Exhaust Relief Cover about a week or two ago. All the channels on the underneath are melted and deformed. With that being said this motor is new to me in 2019 and unsure of maintenance or history from the previous owner.

This weekend I am going to put the new impeller on, replace lower unit gear oil, and link/sync to idle lower.

Also had someone suggest that it could be a coil pack or power pack going bad. Would this make sense for the issue at hand?
 
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Hi All,

Just replaced the water pump impeller tonight. Going back in the morning to tighten a few more bolts and try it out.

Here is a picture of the old impeller... I think it was time :)
IMG_5966.jpg
 
Hi there,

I am fully convinced this is an overheating issue at this point.

I have been tracking the water cooling system for any blockages or areas that need some help.

I have taken the exhaust cover off and it seems like all the seals are dry rotted and brittle so I am going to replace those when putting it back together. It seems like the internal exahst cover is a little worn on the gas flow shaper which is the black thing that helps the gas evaporate down and out the exhaust(not sure of actual term).

Is this inner exhaust cover still ok?
IMG_5973.jpgIMG_5975.jpg
 
What do you mean when you say-----" helps the gas evaporate down and out the exhaust "----Please explain what you think is happening here !-----------Clean those covers and re-install with new gaskets.
 
Sounds good - waiting on the new gaskets now. Committed to figuring this things out!

From what I researched/heard its to deflect the exhaust gases to prevent/avoid turbulence but not exactly sure as I am still learning a lot.

Video at 1:55 is where I heard it...
 
mdoraty said:
Hi there,

I am fully convinced this is an overheating issue at this point.

I have been tracking the water cooling system for any blockages or areas that need some help.

I have taken the exhaust cover off and it seems like all the seals are dry rotted and brittle so I am going to replace those when putting it back together. It seems like the internal exahst cover is a little worn on the gas flow shaper which is the black thing that helps the gas evaporate down and out the exhaust(not sure of actual term).

Is this inner exhaust cover still ok?
View attachment 27287View attachment 27288
Click to expand...
I had this same problem on an 87 Johnson 25. Happens when motor is hot. I was able to narrow it down to the top cylinder losing spark intermittently. I changed coils, power pack and spark plugs trying to fix it. I carried a spark plug cleaning kit in my tool box. That always got me running smoothly again -BUT- the motor could have just been cooling sufficiently while I dinked around with the plug. I ended up selling the boat before I got to the bottom of it all but your post has thinking about it again... I am wondering if it is an overheating issue? Spark plugs are designed to work in certain temp ranges. If the cylinder that is intermittently losing spark is getting too hot that could be the problem. Perhaps an obstruction in water flow somewhere near the cylinder head? After you get it put back together, if the problem persists, try to see if you can feel a temperature difference between the two cylinder heads. I think you may be onto something here. I'll be on pins and needles waiting to hear how this turns out for you..Goood luck! Peace
 
Hi All,

Just updating back here with my results.

Since my last post I have completed replacing the whole water pump assembly, water tube washer, drive shaft impeller spacer(mine was melted/malformed), lower gear unit oil, both exhaust cover gaskets(inner/outer), telltale hose, and head gasket.

After completing the repairs/replacements I performed another compression test. This one came back around 118-120 on both cylinders. After I confirmed this I took the boat back out on the water to run some initial tests. Once I was able to confirm the engine was back in working order I tested for 30mins at WOT without issue.

It has now been a little over 2 weeks since the boat has been back in the water with about 10-12 different uses. The ol' girl has totally come back to life and is running better than ever before.

At the end of the day I truly do believe this was an overheating issue which was causing the intermittent issue in the coil packs described by BoatDope. Appreciate y'all for the tips and recommendations - I know where I'm coming for any outboard help moving forward!

Cheers!
Mitch
 
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