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Evinrude 9.9 E10RCNS power issues

jbird17

New member
Hey everyone, I need HELP.

After pulling this motor out of storage from my father-in-law. I put a fuel pump kit on it as it would not run well. So summer of 2021 it ran fantastic most of the summer until the next to last outing we had late summer 2021. After just putting the boat in the water and running about 10-15min at full throttle, it bogged down to probably 20-30% power at open throttle. It would run with no issues but not get above that 20% power. Adjusting the choke does not seem to change anything. Though it would only idle unless I opened the throttle while not in gear. So I was thinking trash in the lines or carb. I cleaned the tank, checked the Carb and it was clean. Fuel pump was pumping normally. Changed the plugs. Oh, it runs fine on land with the muffs.

So I took it back out for a test run and again, it runs great for about 10-15min then it bogs down. If I shut it down and let it sit for 10 minutes it will run great for 10-15min then bogs down. So my next thought it may be a coil. So I changed the coils and got a new tank and tested on the muffs and ran just fine. We took it out today for test run and again it ran great for 10-15min open throttle then bogs down again! Then it would not idle after that. I will still run fine but only get to that 20% or so power with full open throttle. I shut it down and could barely get it started again. Then it ran for about 10min full throttle then bogged down again.

I am stuck as to what is the problem. It seems to be fuel related. Has anyone had this issue or know what to do!
 
Yes I put a new impeller in when I got it out of storage and I checked it again after these issues. I have not done a compression test. I assumed it was fuel/carb since it runs great for the first 10-15min after cold start. If I let it sit after it acts up then it will run good for a few minutes then act up again.

I will try to get a compression test done.


You have installed a new impeller ?-----Post your compression test values.
 
Check fuel tank venting.-----Does spark on your motor jump a gap of 3/8" ( 1 cm ) on both leads , yes or no ?------Or run with a timing light hooked up to 1 cylinder at a time to see how spark behaves when it falters.-----How does motor respond if you operate the manual fuel pump ?
 
Update: I just test ran it on the stand and it cranks up perfectly. I pulled one spark plug wire off at a time and it ran really rough on each plug at idle. Which is normal right? I then let it run for about 5 min and revved it up a few times to let it get warm. It then started to cough and sputter at higher RPM after letting it get warm. Changing the mixture did not do much.

Before I changed the coils I did this procedure to check the coils after they became hot. Pull each plug wire with it at a mid RPM.

So today I decided to check it again. I pulled the top plug wire off with it in forward gear and slightly high RPM. It did not change the RPM at all when I pulled the top plug wire off. I put the plug wire back on and then pulled off the bottom plug wire. It cough sputtered and tried to die out. I put the plug back on before it could quit and it went back to original RPM. I pulled the top plug again and no change. I pulled the bottom plug wire and it tried to die out. So it seems when it gets warm the top plug is not firing right?

I have two new coils on the engine so what could be causing the new coil to not fire after it runs for 5-10min?

Check fuel tank venting.-----Does spark on your motor jump a gap of 3/8" ( 1 cm ) on both leads , yes or no ?------Or run with a timing light hooked up to 1 cylinder at a time to see how spark behaves when it falters.-----How does motor respond if you operate the manual fuel pump ?
 
They all sound good on a stand.----They bark and roar all day long !!---- IF you answer questions you can help yourself.----Does spark jump a gap of 3/8" ( 1 cm ) , yes or no?
 
Just trying to say I have no spark on the top plug now. Yes....I had 3/8 spark on both plugs on cold start but once I ran it today I have 0 spark on the top plug.

They all sound good on a stand.----They bark and roar all day long !!---- IF you answer questions you can help yourself.----Does spark jump a gap of 3/8" ( 1 cm ) , yes or no?
 
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