2001 Yamaha 90 gremlin.

[fungfumassa]

Main Problem- Missing in low gear idle, up to +/-2000, surging at 3000 rpm-ish when held steady, idles for crap most of the time, then runs great sometimes. random single miss sometimes. Will blast from the dock running great, turn it off and idle like crap.


Alright. So I finally have decided to open a discussion on my problem. Its been a long road but I'll try and give the best representation of what I've done and where I am at.
First off, This is a 2001 Yamaha 90 2 stroke TLRZ motor. got the thing off a bait boat, wouldn't run for s$%t. So to begin with, we fixed that part. Shes got a new lower crankcase seal, fixing pressure problem to begin with. Head was yanked, surfaced and getting a new gasket set, with great compression X 3. Carbs were broke down, cleaned and rebuilt OEM parts, so far twice cleaned. New plugs, new fuel lines, ball, seperator.( non ethanol in a maintained fuel tank) Have gone through 2X new fuel pumps. And even a brand new electric choke selenoid. This is everything to get a good starting point with a motor refurb.

The engine sounds fantastic on the hose. hittin on all 3 usually when you start her at the ramp, by the time you are in gear backing off, shes hittin on 2, missing on the bottom cylinder. As soon as its up on the big jets, runs solid sounds great, like a said a random ping miss every once in a while in the low mid band, but never wot . makes great power when its not running like crap idling.
I've done it all. I will say, everything has been spec'd the best as possible when doing changes, so that means yes, I do sync carbs and adjust jets to within limits after every time messed with etc. same with everything else, not missing the super easy stuff like folks usually tell ya to start with so....
After dealing with my crap idling skiff for a bout a year now, considering i know i have a solid fuel system... I went electrica, pulled the trigger after the stator i have passed ohm test, bought a new stator slapped her on there.
went for a boat ride, and glorious! no problems. Great! next day go fish bait, doing it again. So i know for a fact stators will do some funky stuff, and its always been in the back of my mind that it might be electrical... so back to fuel.
went fishing the other day. got on the hook shut her down, cast look back, i have me a rainbow stream coming from somewhere. im guess carb 3 there on the bottom. burns that out with a nice cloud on the start up, continues to idle like crap. These carbs have been broke down twice, floats set and, have fresh parts, so for the needle to be sticking? i dunno. Dealing with this crap idle issue, left with following fuel for everything. I even thought I had it once, with the electric choke, when it failed a bench test and would get super hot, new one in there got excited, nope still doing it., even a brand new fuel pump at the same time, to rule it out. new gasket behind it too.
Oh and the reeds like fine.
Timing is on the button, no probs with wot any of that, so CDI should be good on pushing the advance, and I've obviously swapped coils around to no avail.

So I got to say, I'm lost now.. I'm thinking id love a set of manual choke carbs that would fit but i just want this stuff right.
So fuel front to back is good that i know of. Electrical is next right? unless you guys solve my rainbow and blue smoke every once in a while prob and that ends up being the whole deal.
OK, a ,little out of order but will update with any more needed info.
Thanks everyone

 

[99yam40]

is the red lever on the prime start system in the auto position?
there is no choke on that motor

 

[fungfumassa]

Roger that, yes I keep checking it to see. But yes I'm thinking about the enrichment system. Miscalling a the primer selenoid a choke. Sorry.
Also, all new little metal reed flap things, New gasket and new selenoid with o ring when rebuilt.
Could I still be missing something at this point ?

 

[fungfumassa]

the valve appears to be functioning when its rotated, it will release fuel. Could fuel be passing by and keeping #3 soaked full?
Its weird, this dead cylinder is within low rpm, and up into 1800 1900. about 2000 you can get it to hit, on and off. You can shut it off, sit for a bit and crank again and might be running well on all 3, get in gear go a ways, back to idle, and miss on 3. So if its fuel related, it should probably have to be in association with the flooded cylinder, correct? new fuel pump that does leak when squeezed, when hooked up, does not create any fluctation when running and forced, so diaphram is good correct? yes, of course it is, or did I get a bad one? lol Fuel is getting sucked in by something, but its doesn't seem to be an every time I'm out problem, with the cloud of smoke. and honestly i've never seen a 2 stroke gas in the water after shut off before, maybe its happened but I'm pretty observant. So was that pouring out of carb 3 overflow, resulting from some random sticking the needle? IS it not adjusted correctly I've got it set right I know that, cause I adjusted it, made it way worse running, went back to spec.
So could there still be a with the enrichement module? like new diaphram installed on that as well. for all known purposes, it functions, cause it takes 2 clicks and she fires up. ohms fine, so know its no resisting somewhere and holding that thing open.
So like I said, I threw a stator on it, because im out of ideas there.

Could these literally be something stuck deeper inside the carb?
ITs done a no power on wot took a long time to spool up thing before, definitely leaving me to think it was electrical. now I'm back to a fuel problem. so
So, Bueller? Bueller?
Anyone?
thanks

 

[99yam40]

to dump gas into #3 the float/needle and seat are not closing off or the fuel pump is dumping fuel into the crankcase
enrichment system would hit all 3 cylinders not just one

 

[fungfumassa]

I'm right there with you. The diagnosis that fuel is infiltrating the 3 cyl from 1 of 2 places. But the for the life of me I can't seem to fix it. Like I said, that's the 2nd new oem fuel pump installed during shake down, and even a known Working used unit was tried to check. The carbs have all been thru twice and can't get it to recreated needle sticking in hand. I'm going to pull just the 3 and break it down for an ubltrasonic bath, ( cause why not clean it some more if it's already apart). I'm almost positive oem kits come with seats so I think I remember installing them along with needles and everything else. Lastly, like I've said rebuilt a few times with some adjustments and can't fix it, what do I do to correct it, as far as I'm aware I'm doing everything correctly