Yammy 40 issues

[Craig cK]

Hi guys, I've recently aquired a Yamaha 40 Autolube (approx 10 - 15 years old) and have a few questions:<br />I took the boat for a long trip (3 hours motoring) and burnt 30-40 litres of petrol. However, only burnt 30ml of oil. <br />The first question therefore is how much oil should the pre-mix use? (what ratio?) The second is how to check it's working. I mixed up some 50:1 on the way back (1.5 hours running) to be on the safe side.<br /><br />Secondly, out last night with 4 divers and 4 sets of gear and was getting 20 knots - I was stoked! Until all of a sudden the revs started dropping and we dropped to 15 / 16 knots. Any clues what could cause this? The fuel filter is clear. I havn't stripped the carbs as yet.<br /><br />Thirdly, a minor one, my tick over is a bit low. How do I tweak this? There is a threaded hole at the top which would crack the throttle open, but there is no bolt - is this it? or else there are little turn screws at the top, side of each carb - what are these?<br /><br />I'm sorry its such a long one...but I'm obviously worried about my poor little engine!<br /><br />Your help last time for setting up the gear shift was spot on! Thank you for that! Saved me hours of playing about!<br /><br />Kindest of regards,<br /><br />Craig K.

 

[Craig cK]

Re: Yammy 40 issues

Another thing!!<br /><br />Occasionally when I go to start it there is a high pitch squeel / squeek for half a second - is this mechanical or could this be some sort of alarm tring to activate? It is pretty loud!

 

[coleman kayak1]

Re: Yammy 40 issues

Secondly, out last night with 4 divers and 4 sets of gear and was getting 20 knots - I was stoked! Until all of a sudden the revs started dropping and we dropped to 15 / 16 knots. Any clues what could cause this? The fuel filter is clear. I havn't stripped the carbs as yet.

Try double-checking the vent on the gas tank

 

[Craig cK]

Re: Yammy 40 issues

No joy I'm afraid! There isn't one! (It's been completely removed)<br /><br />Thanks all the same though!

 

[Dr Jizm]

Re: Yammy 40 issues

sounds like your tickover screw may have fallen out, and I thought you would use more oil than that, the ratio is 100:1 I believe

 

[Biggles]

Re: Yammy 40 issues

I think the squeak is common on that engine. My mates does it and we believe its something to do with the autolube.<br /><br />You get lots of squeaking when its running low on oil.<br /><br />Good thing I suppose...

 

[Craig cK]

Re: Yammy 40 issues

Thank you,<br />100:1 ... so I'm not a million miles out then...still think that I am short though. Does anyone know how to check precisely?<br />So the tick over screw is the one on the top then?<br />Interesting about the squeak! Glad someone else's does it - makes me feel a bit better! I'd love to know why it does it though!

 

[Biggles]

Re: Yammy 40 issues

Craig,<br /><br />My mates does it a lot. You can hear it when you start it quite loudly. Doesn't seem to be a problem.<br /><br />Just keep the oil topped up and it should be okay. <br /><br />Last week he said to me that it seemed to use very little oil and then he ran low 5 miles off shore, with no spare so i had to tow him in.<br /><br />i shall ask him over the weekend how much it uses.<br /><br />What he does do tho is use the proper Yamaha stuff. Which isn't that easy to get over here and costs a bomb....<br /><br />Hope that helps...

 

[Craig cK]

Re: Yammy 40 issues

Thank you,<br /><br />I think that there is some way of holding the engine at say 3000 revs and measuring how much oil comes out the pump (while running on pre-mix).<br /><br />It's scaring me at the moment....so I'm putting a little in with the fuel to be sure! I think it sounds smoother too - although that could be my imagination!<br /><br />I'm surprised if the squeek on mine is oil level related as my little lights at the front don't work so I assume that the level sender unit is faulty.<br /><br />Thanks for the help!

 

[stan_deezy]

Re: Yammy 40 issues

Hi Craig, I thought I'd drop in with a few suggestions based upon experience of a very similar engine (Mariner 40 Autolube). Right from the start I'd say; remember I'm talking about a different engine, but knowing how close some engines are (yam made mercs etc) then it might help.<br /><br />The high pitched squeak was normal on a Mariner and happens when you turn the key and before you start the engine: that is the self test for the autolube low oil alarm. <br /><br />The oil ration varied during running hence it was lower consumption at lower revs and higher at WOT. Over the course of a few hours running at 3000rpm you could see a visual drop in the level but if you were just pottering around it would look like you hadn't used any oil at all.<br /><br />The dropping revs might be several things: fuel (try pumping the primer bulb the next time it happens), ignition (stop and check each plug to see if one isn't firing).<br /><br />Hope this helps?

 

[Craig cK]

Re: Yammy 40 issues

Thanks Bro!<br />That helps, yes I did try pumping the bulb when it happened, but it didn't seem to help. My fuel plug to the engine isn't perfect and has an air leak so I'll replace that and see if that helps.<br /><br />As for the oil consumption...I don't have a tacho, but would guess I was running at 1/2 throttle for 3 hours - 12 / 14 knots on 16 ft boat - capable of 25 with the load on board that day.<br /><br />The high pitch squeal only happens occasionally, but it does sound like it meant to happen - i.e. it's a buzzer rather than mechanical - phew!<br /><br />Unfortunataly when the revs dropped there were four of us aboard and it was dark so didn't really seem to be the ideal time to start playing engines! <br /><br />Thanks for the help again!<br /><br />Can I just confirm that the idle is adjusted by cracking open the throttle and not by advancing the timing or something silly like on Force engines?

 

[Craig cK]

Re: Yammy 40 issues

More questions! Sorry!<br />Can anyone confirm what the horizontal screws are on the starboard side of the engine? Are these the mixture screws?<br /><br />Is there any way of getting more umph (revs) in reverse? This thing is gutless! I fear an impact with a stationary object coming on at this rate!<br /><br />Thanks!

 

[rodbolt]

Re: Yammy 40 issues

quit poking and hoping and buy the factory service manual. the oil consumption test is there someplace. if its a precis motor and not the merc style auto lube its a variable ratio pump. a link from the lower carb goes to a lever on the pump. to test the alarm remove the pink wire from the bullet connector at the temp sender on the head, ground the harness side of the connector to a good engine ground with the key on. if the alarm does not sound repair it. this is only applicable if you have remote controls.<br /> an engine model number may actually help us figgure out what motor ya have,but with 4 people with dive gear your most likly not running the correct prop. ya need to check wot rpm with the load your pulling.the horizontal scews are idle mix scews kind of. the actual mix is done with idle air and fuel jets the screws allow more or less of the mix to enter at idle.