GreasePit Posted July 20, 2016 Share Posted July 20, 2016 Hi raiders,Been having a bit of trouble with my motor recently, and i'm currently on uni break so i want to try fix it asap to make the best use of my free time. When i start the motor at home on dry land, she runs completely fine, when i hit wide open throttle, it hits 7k revs no worries.As soon as i launch the boat in the river, it reaches a maximum of 3.5k revs, and often fluctuates by about 0.5k revs and sounds like its bogging out.Every now and again it will just drop out and stall on me.Motor sounds like it may have a slight rattle.I put in a new tank of fuel as previous to this she was not being used, she is spitting water perfectly, the prop is showing for some very very minor bends.Any ideas or tips would be greatly appreciated.Cheers Link to comment Share on other sites More sharing options...
GreasePit Posted July 20, 2016 Author Share Posted July 20, 2016 I might add, the usual top speed is 20 knots, it currently gets to a max of 6.5.I've taken it out on a few trips and it hasn't changed at all, each time i thought i may have done something to fix the problem, i put it in the water and same go. Link to comment Share on other sites More sharing options...
lyons90 Posted July 20, 2016 Share Posted July 20, 2016 Is the fuel tank breather open? Link to comment Share on other sites More sharing options...
steven22512251 Posted July 20, 2016 Share Posted July 20, 2016 When you are testing it at home are you putting it in gear or just revving it in neutral? Sent from my SM-G935F using Tapatalk Link to comment Share on other sites More sharing options...
Guest 4myson Posted July 20, 2016 Share Posted July 20, 2016 Give our site sponsor a call Shire Mobile Marine 0432 840 245 Link to comment Share on other sites More sharing options...
GreasePit Posted July 20, 2016 Author Share Posted July 20, 2016 Yeah the fuel tank vent is open Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
GreasePit Posted July 20, 2016 Author Share Posted July 20, 2016 When you are testing it at home are you putting it in gear or just revving it in neutral? Sent from my SM-G935F using Tapatalk I'm putting it in gear Link to comment Share on other sites More sharing options...
GreasePit Posted July 20, 2016 Author Share Posted July 20, 2016 Give our site sponsor a call Shire Mobile Marine 0432 840 245 If I can't get a fix out of FR, I may do Thanks mate Link to comment Share on other sites More sharing options...
antonywardle Posted July 21, 2016 Share Posted July 21, 2016 Is the engine getting warm? I was having similar problems in a much bigger engine and it turned out that the thermostats were missing meaning that the engine was always cold, so I couldn't go flat out and I couldn't idle very well. I didn't discover this, it was in the shop. Also, my carbs needed to be rebuilt so I think that they were causing some flooding which made for harder starting. Not something that I could have found myself. This was a Looper 120HP Evinrude. Link to comment Share on other sites More sharing options...
jeffb5.8 Posted July 21, 2016 Share Posted July 21, 2016 Has anything changed on the motor or boat since it was last able to do 20 knots, (Different boat, changed prop, had a home service, new parts added, new gear adding weight, hull full of rain water) When you put it in gear is it getting full movement of the throttle, is the throttle stiff When was its last service (Plugs, compression test), the plugs might look ok but maybe under full load they are not performing, cheap test at $10 for 2 new plugs (I prefer NGK) When you go WOT at home is it in a tank or on ear muff What year, size and model is the engine I had a 25hp Mercury do similar things and it turned out to be the fuel line / fuel Bulb was collapsing at high RPM, cause a reduce fuel flow. Link to comment Share on other sites More sharing options...
GreasePit Posted July 21, 2016 Author Share Posted July 21, 2016 (edited) Is the engine getting warm? I was having similar problems in a much bigger engine and it turned out that the thermostats were missing meaning that the engine was always cold, so I couldn't go flat out and I couldn't idle very well. I didn't discover this, it was in the shop. Also, my carbs needed to be rebuilt so I think that they were causing some flooding which made for harder starting. Not something that I could have found myself. This was a Looper 120HP Evinrude. Engine runs warm, yeah the more and more i look into it by checking off all the easy fixes, the more it looks like its going to be a bigger problem unfortunately. B.O.A.T - Bust Out Another Thousand Has anything changed on the motor or boat since it was last able to do 20 knots, (Different boat, changed prop, had a home service, new parts added, new gear adding weight, hull full of rain water) When you put it in gear is it getting full movement of the throttle, is the throttle stiff When was its last service (Plugs, compression test), the plugs might look ok but maybe under full load they are not performing, cheap test at $10 for 2 new plugs (I prefer NGK) When you go WOT at home is it in a tank or on ear muff What year, size and model is the engine I had a 25hp Mercury do similar things and it turned out to be the fuel line / fuel Bulb was collapsing at high RPM, cause a reduce fuel flow. So about 6 months ago, dad hooked the boat up and ran the motor at home, one of our naughty dogs decided it would be fun to take the earmuffs off while dad was away from the boat, cooked all the internals. Only got it fixed a month ago, my first launch since was maybe 3 weeks ago, it revved past 3.5k no worries for about 2 minutes, and all of a sudden dropped out and since then it has been the same. I found that when the mechanic was tampering around the engine he had accidentally placed the fuel filter in a spot which made a kink in the line, i moved that and unkinked it, thinking that would be the problem. Went back out again later, still the same. No water in the hull. Everything else is the same on the boat except for the service it had on the motor. Throttle moves all the way, i checked the throttle and shifter linkages and they all seem to be moving as they should. Yeah i might go buy some new plugs this arvo. Not 100% on last service, ill have to ask the old man. With an ear muff at home. Its a BF30 from either 2004 or 2005 That would make sense to be honest, next time i run it ill check the fuel line/bulb to make sure its not collapsing. Cheers for your replies guys, really appreciate it Edited July 21, 2016 by Laborgatory Link to comment Share on other sites More sharing options...
antonywardle Posted July 21, 2016 Share Posted July 21, 2016 Ok, so I would take it back to the person that fixed it, as I'm guessing that you've got some warranty. If it was a mate or a friend of a friend then I guess you'll have to think of something else. Any idea what work was done to fix it after the over heating? Link to comment Share on other sites More sharing options...
GreasePit Posted July 21, 2016 Author Share Posted July 21, 2016 Yeah it was done by a mechanic. He installed a new impeller and water pump Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
jeffb5.8 Posted July 21, 2016 Share Posted July 21, 2016 I think first stop would be a compression test as the overheating could have damaged the rings or head. Link to comment Share on other sites More sharing options...
recurve Posted July 22, 2016 Share Posted July 22, 2016 (edited) So he installed a new impeller and water pump..... I had a similar issue with my motor and it stumped me and the mechanics. Mainly as the alarm had been disconnected...don't ask. The cause was corrosion in the cooling chambers had restricted the water flow. The Engine was self preserving and lowered the revs so it did not overheat. The fix was to open the thermostat permanently to increase the flow. I only wanted a temp fix as wanted a new motor. I have a new motor now so happy days. The other think the marine mechanics thought it could be was either bad fuel, water in the carbs or gunked up nozzles due to using fuel with Ethanol. Which I have never done! If he replaced your water pump maybe you have an issue with water flow or you have restricted fuel flow due to gunk. Edited July 22, 2016 by recurve Link to comment Share on other sites More sharing options...
Cargo05 Posted July 22, 2016 Share Posted July 22, 2016 Is the impellor the same as the last one? Sometimes this can make a big difference. Link to comment Share on other sites More sharing options...
GreasePit Posted July 22, 2016 Author Share Posted July 22, 2016 Cheers for all the replies fellas, puts a twinkle in my eyeAn update on the situation:I found another forum in which another bloke had a similar problem which has shed some light on the situation (or should i say antonywardle found it)I think the cause may be a clogged up jet in the carby. I took each spark plug cable off whilst idling, bottom two the revs dropped, top one the revs stayed the same (it also didn't zap me).Switched the plugs to make sure the spark plug wasn't the issue, and still when i took the cable off, top one didn't drop the revs. There's a youtube tutorial on how to clean the carby out for the Honda BF30, depending on if i have some extra time to fiddle around with it for a day, may do that, or to be safe may take it to a mechanic. Link to comment Share on other sites More sharing options...
jeffb5.8 Posted July 22, 2016 Share Posted July 22, 2016 If you have a spare spark plug (any will do) take the top ignition lead off and put the spare plug in it and start the motor and see if it's sparking, if it's sparking the it will be either fuel or compression in that cylinder. Try some carby clean sprayed into carby and carby cleaner in the fuel tank with fresh fuel and run it. Link to comment Share on other sites More sharing options...
tackleberry Posted July 22, 2016 Share Posted July 22, 2016 you said it didn't zap you so it's a spark issue not fuel Link to comment Share on other sites More sharing options...
recurve Posted July 23, 2016 Share Posted July 23, 2016 Carbs are not hard to take apart and put together. If you have blocked Nozzles/Jets then you are better replacing them so need to buy a Carb Kit. Putting back together is not hard but I found getting the Carbys tuned up again required the dab hand of an expert. Good luck. Nothing more frustrating than a dicky motor Link to comment Share on other sites More sharing options...
GreasePit Posted July 23, 2016 Author Share Posted July 23, 2016 you said it didn't zap you so it's a spark issue not fuel I swapped some sparks around, The spark plugs themselves are not the issue Maybe the top cable, but the top plug worked fine in the middle port Link to comment Share on other sites More sharing options...
GreasePit Posted July 23, 2016 Author Share Posted July 23, 2016 If you have a spare spark plug (any will do) take the top ignition lead off and put the spare plug in it and start the motor and see if it's sparking, if it's sparking the it will be either fuel or compression in that cylinder. Try some carby clean sprayed into carby and carby cleaner in the fuel tank with fresh fuel and run it. Yeah I'll pop down to the local and grab some carby cleaner, see if that works Cheers mate Link to comment Share on other sites More sharing options...
GreasePit Posted July 23, 2016 Author Share Posted July 23, 2016 Carbs are not hard to take apart and put together. If you have blocked Nozzles/Jets then you are better replacing them so need to buy a Carb Kit. Putting back together is not hard but I found getting the Carbys tuned up again required the dab hand of an expert. Good luck. Nothing more frustrating than a dicky motor I'm not very mechanically minded, trying to learn so I know what's going on with my motor if something plays up though. I'll rewatch the tutorial on how to clean the carbs on the bf30 a few times and give it a crack It's a temperamental little thing Likes to play up when I have free time Link to comment Share on other sites More sharing options...
jeffb5.8 Posted July 23, 2016 Share Posted July 23, 2016 (edited) I swapped some sparks around, The spark plugs themselves are not the issue Maybe the top cable, but the top plug worked fine in the middle port The plug is fine I think the issue is the cable or the coil for that top cylinder, that's why I suggest putting a spare spark plug on that cylinder to test if it is sparking. If it doesn't spark then that is your issue, you then need to find out if it's the lead or the coil. If the coils are the same you could swap and then do the running test and see if the dead cylinder has moved. Just remember you cannot just swap the cable as the leads spark at different times for engine timing. If it was a fuel issue it would affect all cylinders not just one unless it was a injected motor. Edited July 23, 2016 by jeffb5.8 Link to comment Share on other sites More sharing options...
jeffb5.8 Posted July 31, 2016 Share Posted July 31, 2016 Hi mate did you get a chance to play with your motor? Link to comment Share on other sites More sharing options...
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