8hp Evinrude running poorly.

[dieselfuelonly]

sorry for the previous double-post. I do see you have an aftermarket double coil. in my experience, they are horrible. Ive had 4 just this season go bad in under an hour of running. it still might be ignition related. the sensor coil was tested? one easy thing to do to rule out ignition is get a set of coil extenders from stevens electronics or CDI. hook a dva meter up to it. voltage should be a steady 200-400v. if its dipping/breaking up, you know its probably the pack, ignition coil, or sensor coil. sometimes issues like that are as simple as a bad plug or plug wire as well. all easy to test and will show up with the coil extenders.

Original sensor coil tested good, although the voltage produced was WAY higher than spec when tested with DVA. Replaced it early on in my testing on this motor, although I believe there was no issue with the original sensor.

New aftermarket power pack, still have what I belive is the OEM original which as far as I can tell is good as well.

I did replace the ignition coil as #2 cylinder had a much weaker spark than #1. #1 would jump a 3/4" gap, #2 barely 1/4". Both jump a 3/4" gap now with the aftermarket coil.

99% sure there are no issues with ignition stuff now, although I realize the aftermarket components can fail pretty quick.

I need to find a known good carburetor to put on this thing to test it. But I don't know how or where to find one. Seems I would have to buy another complete running motor to get a known good one. It seems strange to me that the aftermarket never got into making carburetors for these engines. Why? I can get on eBay or Amazon and get an aftermarket carb to fit just about any other small engine out there. Of course quality varies greatly, but they are out there. I have one on my 4HP Yamaha 2-stroke that I got off Amazon for $60 that runs absolutely fantastic now.

This thing is just gonna sit in my garage until I can test it with a good known carb, which will probably never happen because how am I supposed to get one. I'm done spending money on it. This was the first small 2-stroke outboard I bought used, and I learned my lesson.

Here's what I've spent on this thing so far for the engine and parts, shipping and what not included:

$800 for engine (guy I bought it from told me it was a 2000s 9.9 LOL, I didn't know any better and there were no serials/markings on the case)
$46 for new nozzle well
$75 for powerhead gasket set
$60 for fuel pump
$19 for fuel pump rebuild kit
$10 for Amphenol connector removal/installation tools
$38 for ignition coil
$30 for DVA adapter for my multimeter
$30 for sensor coil
$32 for a good carb rebuild kit
$17 for a cheapo carb rebuild kit
$68 for power pack
$75 for used carburetor
$15 for new spark plugs

And who knows how many hours of my time spent testing on this thing trying to diagnose the problem.

So I've got $1315 into this thing. NO MORE throwing parts and money at it. I've gotten way to caught up in "well let me get this to test this component because that HAS to be it!".

So sorry to disappoint anyone who was hoping to see the outcome of this thing. If I can ever get ahold of a known good carb I'll gladly spend the time to throw it on there and see the results. I'd still like to get it running right for my inflatable... my 4HP Yamaha is great but underpowered for trying to get an inflatable up on plane.

I also have a late 60s-early 70s (believe its early 70s) 9.9 Merc 110 I got from someone at work for $200. Needs a water pump and at the very least a carb rebuild. Wonder if I'd have any better luck with that one.

 

[racerone]

Nothing goes wrong with these carburetors that would warrant a complete replacement.----No demand therefor no one is going to set up to make these !!!

 

[dieselfuelonly]

Nothing goes wrong with these carburetors that would warrant a complete replacement.----No demand therefor no one is going to set up to make these !!!

Fair enough. So I know you are very experienced with these engines racerone, what would your thoughts be on this engine if not a carb issue?

 

[racerone]

I usually test stuff and rarely install parts by the guessing method.----When I see the score marks like in your video, the motor comes apart for inspection.-----No hesitation on that.-----I hope to pick up a 1994 long shaft model 8 HP for less than 1/2 of what you have invested.---Not run for over 10 years.----Might need to install a new impeller.-----Test run your motor with a timing light , 1 cylinder at a time.----See if there is an ignition issue.

 

[dieselfuelonly]

I usually test stuff and rarely install parts by the guessing method.----When I see the score marks like in your video, the motor comes apart for inspection.-----No hesitation on that.-----I hope to pick up a 1994 long shaft model 8 HP for less than 1/2 of what you have invested.---Not run for over 10 years.----Might need to install a new impeller.-----Test run your motor with a timing light , 1 cylinder at a time.----See if there is an ignition issue.

I have tested with timing light, have not seen any ignition issues. I will tear it down and take pictures. If I cannot find anything wrong will re-assemble with the rest of the new gasket kit for the powerhead, and test run again.

I don't think you are near me (I'm in North Carolina USA), but would you be interested in taking a look at the powerhead if I cannot resolve this myself? I could ship powerhead with carb and anything else you wanted for testing if you are interested. I would of course pay for time and all shipping costs.

I have the head off now and reed valve body off, will take some pictures and upload shortly.

 

[racerone]

Sorry----You are too far away.----Have a 91 model that was given to me.----Bad compression on one cylinder.----I have O/S piston and rings ( listed as NLA ) on hand.----Easy fix for me.

 

[dieselfuelonly]

Sorry----You are too far away.----Have a 91 model that was given to me.----Bad compression on one cylinder.----I have O/S piston and rings ( listed as NLA ) on hand.----Easy fix for me.

Completely understand. I hope you don't mind I pick your brain on here instead. It would be greatly appreciated.

I got the powerhead off again and started disassembly. Got some pictures. Don't have the crankcase split apart yet. I don't want to take off the exhaust port covers as those have my new gaskets and sealant on them, I don't want to destroy the gaskets and have to order another kit.

Reed valve plate, all valves lay nice and flat, nothing proping them open, no warps or bends

Underside of powerhead, curious about the overall dampness towards the fuel pump side. New lower crank seal, so shouldn't be any leaks from there.

Exhaust downpipe removed

Spacer plate removed

Old gaskets

Top of exhaust downpipe assembly

Cylinder head

Carb mounting plate

Looking down in midsection

Head gasket, did not see any issues here

Cylinder walls. Some light scoring, but nothing I can feel with my fingertip. Crosshatching still visible

Here is the one thing I did find interesting:

Looking at the exhaust ports on both cylinders, they appear much rougher than the intake ports. The intake ports are very cleanly cut. Perhaps this is normal from the machining process depending on what direction the tooling enters the block, but there is what appears to be some chipping around the outer edges of the ports and some hand machining marks. What are your thoughts on this, normal? I hope someone didn't take a die grinder to the exhaust ports for some reason...

Thoughts? I'll finish disassembly soon.

 

[racerone]

Pictures of piston skirts will tell the story I think.

 

[dieselfuelonly]

Pictures of piston skirts will tell the story I think.

Got it torn down all the way. Everything looks good to me. Not perfect, but good in my opinion.

Plenty of pictures below to check out. I can finally confidently say I don't think piston skirts is the problem.

Intake side of crankcase

Crank and pistons still in case

Center crank bearing

Crank

Exhaust side of pistons

Intake side of pistsons

Intake ports

Exhaust ports

 

[racerone]

I am surprised at the condition of these parts.----So just a quick hone and reassemble.-----Then more trouble shooting.---Sorry I can not be of more help.

 

[dieselfuelonly]

I am surprised at the condition of these parts.----So just a quick hone and reassemble.-----Then more trouble shooting.---Sorry I can not be of more help.

All good, at least we know the internals seem to be in good shape, and I'll have a freshly sealed up powerhead.

 

[oldboatfixerupper]

It's probably something simple like faulty spark plug wires or a bad ground. I was rewiring my boat and I had everything right. I knew I had everything connected properly and my trim wouldn't work. It was a rusted connector from the relay box to the trim motor.