jay_stylz Posted December 9, 2013 Share Posted December 9, 2013 So guys after a horrible first day out on the water with the new boat I am now stuck with fixing some issues with the motor . Before I took the boat out that day I replaced the plugs started it up and ran it on numerous occasions the motor didnt have an issue started first go everytime but it seems now it's running horrible and won't idle down low after the trip out we did notice a hole in the cylinder had which has now been replaced with new gaskets and cylinder head cover but the motor still seems to be acting strange dropping cylinders down low but seems to be ok when the rpm is up high I really have no idea what this could be note I didn't replace the fuel in the tank I just filled it up which could be my undoing not knowing how old it was but as I said idled fine when was on the old fuel Any ideas what this could be ? Link to comment Share on other sites More sharing options...
jay_stylz Posted December 9, 2013 Author Share Posted December 9, 2013 Also it's a yamaha 70 hp (3 cylinder) Link to comment Share on other sites More sharing options...
Testlab Posted December 9, 2013 Share Posted December 9, 2013 A tank of old, stale bad fuel will cause all that. Including blowing a hole through a piston or other damage caused by detonation. I think it's time to clean or replace that tank, remember to purge the fuel line, then strip the fuel system and carbys cleaning everything thoroughly. What kind of hole in the cylinder head? All the way through? Link to comment Share on other sites More sharing options...
Guest Aussie007 Posted December 9, 2013 Share Posted December 9, 2013 i know not everyone is mechanically inclined but u mention there was a hole in the cylinder than u replaced the head gasket and head these are different parts so ill assume u had a blown head gasket, did u do a compression test after u replaced the head gasket and before u used the engine? i suggest u do a compression test now and let us know the readings if the engine wont run at idle speed and its revving up u might have a air leak or lack of fuel flowing into the carbies Link to comment Share on other sites More sharing options...
jay_stylz Posted December 9, 2013 Author Share Posted December 9, 2013 Sorry guys meant to write cylinder head cover my bad and yeh was all the way through never seen such corrosion I'll post up some piks soon Link to comment Share on other sites More sharing options...
Guest Aussie007 Posted December 9, 2013 Share Posted December 9, 2013 Sorry guys meant to write cylinder head cover my bad and yeh was all the way through never seen such corrosion I'll post up some piks soon if it was corrosion good chances are your engine block is toast, the salt eats away at the cylinder wall around where the head bolts on and u end up loosing compression into the cooling system Link to comment Share on other sites More sharing options...
jay_stylz Posted December 9, 2013 Author Share Posted December 9, 2013 yeh thats what im worried about although i did pull the head gasket off and replace it they didnt look to bad which i suppose is a good sign just trying to work out why it wotn idle properly when before i took it out it had no drama :/ Link to comment Share on other sites More sharing options...
jay_stylz Posted December 10, 2013 Author Share Posted December 10, 2013 So I wonder if this could have anything to do with the idle issue the top one is shut while the bottom 2 are still open with a few mm Link to comment Share on other sites More sharing options...
ron.c Posted December 10, 2013 Share Posted December 10, 2013 it wont idle when you got it on full choke like that. Link to comment Share on other sites More sharing options...
Testlab Posted December 11, 2013 Share Posted December 11, 2013 As Ron said, that's the choke you've pushed closed. It doesn't matter if the choke plates don't all sit the same. If you've got carbs full of junk then it's likely you've also got a bad imbalance between them, which won't be doing the engine any good I you try and run it like that. Pull, strip, clean and kit them. New spark plugs. New fuel filters. Clean and purge everything fuel related and try again. Before removing the carbs write down how many turns each individual mixture screw is set to. Link to comment Share on other sites More sharing options...
dunc333 Posted December 12, 2013 Share Posted December 12, 2013 before you throw any cash at it +1 to what gazza said do a comp test or better still a leak down test and let us know what your comp results are and you can then move on to the carbs better to be safe than sorry.cheers dunc333 Link to comment Share on other sites More sharing options...
jay_stylz Posted December 13, 2013 Author Share Posted December 13, 2013 sorry guys out of all the toold i dont have a compression tester lol but my mate is hopefully coming around this weekend strange enough i gave the carbys a bit of a clean changed one seems to be idling a lot better but still coughing and spluttering after it warms up kinda strange if u ask me i cant work it out really starting to anoy me but yeh has new plugs and things in it seems to be starting alot better also so i guess some posotives there hey i really have no idea what could be wrong with it Link to comment Share on other sites More sharing options...
jay_stylz Posted December 14, 2013 Author Share Posted December 14, 2013 We'll some good news guys the motor is now running great after the carby jets were cleaned and adjusted ....... The jets were complelty blocked dunno how the motor was even running but a big thanks to mate Jeff and we now have a perfect running outboard big relief it was nothing to major Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now