Doza48 Posted July 24, 2018 Share Posted July 24, 2018 Hey Guys, Hope someone can help me, I bought my first boat about 8 months ago and apart from not being able to catch many fish i have been loving it so far, Its a Quintrex 420 with a 2 stroke Yamaha 40HP CV on it, I had a slight problem where if i took it to full throttle after a few mins it would conk out and i would spend the next 10 mins getting going again, but once i did it took off like nothing was wrong, I didn't think too much of it and just though it didn't like to go full on so for the last 6 months i have only gone at about 75% and all has seemed fine with that, Until the last 2 time i took the boat out and i got going no problems motored along for 15 mins at 75% throttle but as soon as i powered down it cut out again and took 10 mins to get going, and every time i stopped from then on it takes so work get it running again. All i want to know is if i am doing something wrong i don't know about, I don't wanna keep doing it especially if its just something simple? or do i just need to get a service? Link to comment Share on other sites More sharing options...
rozza_b Posted July 24, 2018 Share Posted July 24, 2018 There's a whole number of things that could possibly cause what your describing and by the sounds of it I don't think many of them would be caused by what your doing, when the engine last serviced ? If not recently I would probably be looking at getting that done first, discuss the issue with your mechanic as well and see what they think 1 Link to comment Share on other sites More sharing options...
kingie chaser Posted July 24, 2018 Share Posted July 24, 2018 Is it under warranty? Can you take it back to the dealer?? Breather opened enough on the tank?? Yeh you could throw a dart as the what the problem is but sounds like a fuel issue but that's a guess of course & it could be something as trivial as a faulty kill switch? For piece of mind just take it in for a service & explain the problems so the tech can test it under similar conditions. 1 Link to comment Share on other sites More sharing options...
GoingFishing Posted July 24, 2018 Share Posted July 24, 2018 If the motor is conking out while running then my guess is a problem with the fuel supply. Perhaps a blockage in the fuel line somewhere that has progressively gotten worse. Fuel filter? 1 Link to comment Share on other sites More sharing options...
Hill373737 Posted July 24, 2018 Share Posted July 24, 2018 I agree with the suggestions re having it serviced, if its not due for a service, find a mechanic who is happy to go out with you in the boat to ensure you can show him the problem. I had a weird issue with my 50hp 4 stroke where it ran perfectly up to 4200 rpm then would alarm and go to limp mode. No codes showed up in the workshop but 20 minutes on the water and the mechanic had it sussed. 1 Link to comment Share on other sites More sharing options...
Doza48 Posted July 24, 2018 Author Share Posted July 24, 2018 Thanks guys. I thought that might be the suggestion, just wanted to know if I was doing something simple wrong. Much appreciated Link to comment Share on other sites More sharing options...
JonD Posted July 24, 2018 Share Posted July 24, 2018 (edited) Is the fuel under floor or simply in a plastic removable tank ? Often the issue you describe happens when the air breather on the portable tanks isn't fully open as kings chaser mentioned. ( the exact thing you describe ). Edited July 24, 2018 by JonD 1 Link to comment Share on other sites More sharing options...
jeffb5.8 Posted July 24, 2018 Share Posted July 24, 2018 What is the fuel bulb like on the fuel hose, my Mercury did the same thing, 80% throttle no problems but 100% throttle and it ran for about 500m then dies, primer bulb felt hard and look like new. i found the inside of the bulb was collapsing at high revs and it would reduce the fuel flow. Very cheap to buy a new hose and fuel bulb, so I did that and it fixed it. the other things to check are the fuel tank vent, if it’s a portable tank, see if the tank is compressing or suck in when running. check the fuel filter and spark plugs when you are going flat out try pumping the primer bulb on the tank and see if that fixes it as it maybe the fuel pump is weak. 1 Link to comment Share on other sites More sharing options...
JonD Posted July 24, 2018 Share Posted July 24, 2018 If you have checked the things mentioned and found no problem, could you possibly borrow a plastic fuel tank with Yamaha connector hose to test on your boat. If you can borrow from a mate be sure to use all the fuel before giving it back ? 1 Link to comment Share on other sites More sharing options...
rickmarlin62 Posted July 25, 2018 Share Posted July 25, 2018 definetly starving for fuel..either blocked breather ..or sucking air at joins of line to tank or bulb or connector at engine...if hose feels hard and not pliable replace fuel ine and bulb...rick Link to comment Share on other sites More sharing options...
Fishop Posted July 25, 2018 Share Posted July 25, 2018 18 hours ago, Hill373737 said: I agree with the suggestions re having it serviced, if its not due for a service, find a mechanic who is happy to go out with you in the boat to ensure you can show him the problem. I had a weird issue with my 50hp 4 stroke where it ran perfectly up to 4200 rpm then would alarm and go to limp mode. No codes showed up in the workshop but 20 minutes on the water and the mechanic had it sussed. What was the issue in that case? Link to comment Share on other sites More sharing options...
back cruncher Posted July 25, 2018 Share Posted July 25, 2018 Hi all...sounds like fuel.to be sure,next time it happens take a spark pluug out and see if its wet with fuel,or dry.if the plug is dry,its fuel.if its wet its spark. Or,you could earth the plug out on the motor with the spark plug cap on,crank the engine over and see if you have spark. Link to comment Share on other sites More sharing options...
Fishop Posted July 25, 2018 Share Posted July 25, 2018 Just curious could a mechanic replicate this issue in his shop or would he have to take it out on the water to get the revs up past 75%? Or do they just take the prop off and put it in a bucket? Link to comment Share on other sites More sharing options...
PaddyT Posted July 25, 2018 Share Posted July 25, 2018 Am guessing fuel, could be perished bulb/fuel lines collapsing in as fuel demand increases, make sure breather on tank is fully open should be a simple fix Link to comment Share on other sites More sharing options...
Hill373737 Posted July 25, 2018 Share Posted July 25, 2018 3 hours ago, Fishop said: What was the issue in that case? Dodgy thermostat. 1 Link to comment Share on other sites More sharing options...
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