Trying to narrow down starting issues ('97 Evinrude 25HP 3cyl)

[WhiteRice]

Was wondering if anyone had ever experienced hard starting issues as a result of a clogged or obstructed exhaust port(s)...?

I am still having intermittent issues with starting (rope start) this thing after trying virtually everything I have read and the advice I have been given. The other day I was pulling the plugs just to double check compression again after I ran the motor and I am still getting a solid 120, 121 and 119 across all three cylinders. Something I couldn't help but notice is how similar the resistance felt while pulling the rope with the plugs out vs. when the motor actually wants to turn over. I would say there is about a 50% difference in the effort it takes to pull the rope with the plugs out vs. when they are in. I know that there will be some difference since I basically have zero compression with them out but I can't help but notice the similarity between when it won't turn over compared to how it feels when it will. It is possible to have too much back pressure from my prop or mid section exhaust as a result of an obstruction? I know the motor was running VERY rich when I was struggling with the carbs and since I premix... could there be residue that has accumulated there that I cannot see that's keeping the motor from having an easy start?

 

[racerone]

With plugs out there will still be compression in the crankcase.-----Do you have spark that will jump a gap of 3/8" or more, yes or no ?

 

[WhiteRice]

I have a clean, blue spark at nearly 1/2" (had my wife record it while I was pulling it a month or so ago). I guess I shouldn't have said "zero compression" but there is an obvious difference when pulling it with the plugs out.

 

[racerone]

???------Yes it should be easier to pull when plugs are out !!---And have you checked condition of the lower unit ?----And if ports were plugged you would not get full throttle power and performance.----How does it run once started ?------I have seen issues with the wee plastic crankshaft / crankcase seals.----That is not easy for a novice to check.-----Took one of these motors apart last month and someone ( club fisted ) had assembled it without putting bearings onto the dowels.----Block is now scrap.

 

[WhiteRice]

I understand it will be easier to pull with the plugs out. But my observation is that when the motor does want to turn over, the resistance feels similar to when I am pulling it with the plugs out. I have not inspected the lower unit beyond a gear oil change. I would revert back to my original question about the exhaust ports and can hard starting be a result of a clogged port(s)? If so, is there a procedure for cleaning them?


***response to the edit***

The motor has not been running at full power for about a month. I would say at about 80%. It will still plane out my boat quickly but I was getting 27mph with two people 2 months ago and now I max out at about 19-20mph

 

[racerone]

I doubt posts will be plugged.----Maybe someone with a fancy cellphone and camera probe can inspect for you.----Or just pull the head off to look.

 

[WhiteRice]

Out of curiosity... What should I look for in regards to the lower unit that would prevent a normal start?

 

[racerone]

Oil was changed.----No mention made of water.----Then I assume after that bit of info was posted that there are no lower unit issues !

 

[WhiteRice]

Oil came out of lower unit clean from what I could tell. No streaks of grey as it was draining

 

[racerone]

You mentioned / asked about the effort required in pulling the motor over !----That is why I asked about condition of the lower unit !----Good luck with your trouble shooting.

 

[WhiteRice]

***EDIT*** Or if anyone knows the steps for this


racerone... In another post you mentioned adding a primer to this unit vs. using the choke. I have done some searching but can't seem to find much info on adding a primer to this motor. Any insight on where I can find this info? I just want to make sure I cover all bases when trying to solve this issue.

 

[WhiteRice]

***edit***