magicaltrout Posted August 27, 2019 Share Posted August 27, 2019 Hi folks, I doubt this can be diagnosed by video but I have one any way! Fired the boat up for the first time in a couple of weeks and it's started stalling at low revs and very much when you stick it in neutral. I checked the spark plugs to ensure the seemed connected but this pretty much exhausts my knowledge at this point.. https://photos.app.goo.gl/iirBFMn7fti5YPD1A It's supposed to be getting serviced in a few weeks so I'll probably have to wait until then but worth an ask! Thanks Tom Quote Link to comment Share on other sites More sharing options...
grendel Posted August 27, 2019 Share Posted August 27, 2019 dirt in the fuel?, blocked fuel filter? blocked injectors? Quote Link to comment Share on other sites More sharing options...
Turnoar Posted August 27, 2019 Share Posted August 27, 2019 Bag round the prop? 1 1 Quote Link to comment Share on other sites More sharing options...
magicaltrout Posted August 27, 2019 Author Share Posted August 27, 2019 Thanks @Turnoar, I did get in the water and have a feel around today but didn't find anything. That said, if its in neutral, the prop isn't spinning is it so it shouldn't affect its stall-ability? In gear I could understand it. Thanks @grendel, this is where it gets beyond my limited knowledge, I'll get the service guys to look at it and hopefully they can give me some tips for next time :) Quote Link to comment Share on other sites More sharing options...
scaniaman Posted August 27, 2019 Share Posted August 27, 2019 Could be the idle speed sensor, on some younger model engines they use sensors that regulate the engine revs, which means you cant just turn an idle screw to regulate the tickover speed. If you have the Mercruiser model number it may be possible to get some information to help you. Should be called a throttle position sensor I think. Paul Quote Link to comment Share on other sites More sharing options...
magicaltrout Posted August 27, 2019 Author Share Posted August 27, 2019 Thanks @scaniaman I did have a scan through the manual this afternoon but didn't find anything about adjusting the idle RPM and as you barely get a signal at St Olaves gave up trying to Google it. I will dig out the model number tomorrow, forgot to make a note of it today. That said, as it was working find on each test run we had with the boat and until a week or so ago, I had wondered if I could find a way to adjust the idle RPMs but it also felt like it was probably a fudge as opposed to a fix as it has gone from fine, to not great, to just flat out stalling on a warm engine in 2 cruises. Quote Link to comment Share on other sites More sharing options...
dnks34 Posted August 27, 2019 Share Posted August 27, 2019 Whats the fuel level like, if its been running low it could have picked up some sludge or gunk in the tank. Quote Link to comment Share on other sites More sharing options...
magicaltrout Posted August 27, 2019 Author Share Posted August 27, 2019 Yeah I wondered about fuel, old fuel etc, when we bought it it was basically empty so NYA stuck 40L of fresh fuel in it and I've filled it up a bunch of times and its currently got 70ish Litres in it, so I don't think it should get too sad on 1/4 tank. But yeah fuel supply had crossed my mind. Quote Link to comment Share on other sites More sharing options...
Lastbutnotleast Posted August 27, 2019 Share Posted August 27, 2019 What engine is it? Is it inboard or an outboard. Quote Link to comment Share on other sites More sharing options...
magicaltrout Posted August 27, 2019 Author Share Posted August 27, 2019 Inboard @Lastbutnotleast Quote Link to comment Share on other sites More sharing options...
Lastbutnotleast Posted August 27, 2019 Share Posted August 27, 2019 Yes sorry it's obvious if you watch the video. 1 Quote Link to comment Share on other sites More sharing options...
scaniaman Posted August 28, 2019 Share Posted August 28, 2019 If you give me the model number MT. I can have a ferret around online see if anything pops up. Paul Quote Link to comment Share on other sites More sharing options...
annv Posted August 28, 2019 Share Posted August 28, 2019 Hi check around carb and look at all the little hose connections they often perish and let air into carb giving it a lower fuel mixture at slow tick over engine speeds it is not noticeable at higher higher speeds if all ok, remove air hose on top of carb rev engine up at the same time place your hand NO RAG over the carb inlet at the same time flip the throttle open to increase vacuum and flush petrol through jets, as engine stalls/slow down remove your hand before it stalls and gently rev the engine up this will hopefully suck/clean the residue from the jets that accumulate from petrol when it drys out you should always turn the fuel off and run the engine dry when leaving it for any length of time, if you have a diaphragm fitted it could have a pin hole in it through pershing, which will need replacing, couldn't see what carbs you have but petrol leaves a shellac stain on brass when it drys out and the jets are made of brass. if this doesn't work you will need a engineer to check it over. if you have two engines it is good policy to only run one at a time as they often don't get run fast enough on the broads due to speed restrictions.John Quote Link to comment Share on other sites More sharing options...
magicaltrout Posted August 28, 2019 Author Share Posted August 28, 2019 Thanks for the hints, tips and advice folks, @scaniaman's tip wins! :). I went back through the manual today and found the idle RPM screw and gave it a tweak which solved the issue for now. I also got a pretty detailed explanation from Peter at Northgate Marine who explained the whole transmission, ignition setup and explained how this is a reasonably common problem especially for sticky cables. Anyway! Back up and running for now and its going to get serviced soon anyway, so I'll get them to clean it up and get it running well again in a few weeks. Tom 1 Quote Link to comment Share on other sites More sharing options...
Smoggy Posted August 28, 2019 Share Posted August 28, 2019 Easiest way to check for air leaks is to run at idle and spray wd40 or brake cleaner round the carb and Inlet manifold, if rpm picks up you have an air leak. Quote Link to comment Share on other sites More sharing options...
annv Posted August 29, 2019 Share Posted August 29, 2019 Hi Tom As you have just bought it i would check the fuel tank for water that collects in the bottom from condensation, more so on petrol as people don't tend to keep petrol fuel tanks full over winter unlike diesel. petrol tanks don't have a drain of tap to purge water from bottom of tank like diesel one's do, weight/tip the boat over to the fuel filler side leave for a while then with a 1/4 inch length of hose insert to lowest corner of tank through filler and suck/pump out into clear container you will see the difference between petrol and water, you my well find that the bottom of tank has water in it this is from condensation that accumulates over time, and when it gets high enough to reach the fuel outlet pipe level then collects in bottom of carburetor bowls affecting the slow speed running fuel mixture. John Quote Link to comment Share on other sites More sharing options...
magicaltrout Posted August 29, 2019 Author Share Posted August 29, 2019 Thanks John, thats handy advice I'll take a look! Quote Link to comment Share on other sites More sharing options...
Gretzky Posted August 29, 2019 Share Posted August 29, 2019 Mercrusier 5.7 by the looks of it. Basically a marinized small block Chevy. Check the auto choke is not sticking, also they don’t like running cold, does it idle once its warmed up? There should be a water separating fuel filter in the fuel line, worth a check, just take it off an pour the contents into a glass jar and let it settle out, any water will sit on the bottom. Other than that could be a blockage in the idle circuit in the carb, they are not too complicated to strip and clean blow the jets out with a can of carb cleaner. Once warm it should idle about 650-700 rpm. If it is stalling going into gear there is an interrupter micro switch on the gear shifter, this intentionally stalls the engine for a fraction of a second while going in to gear, may need adjusting. After all that I guess it probably an electric fuel pump, so check the connections for any corrosion. (been there done that :D) Quote Link to comment Share on other sites More sharing options...
MauriceMynah Posted August 29, 2019 Share Posted August 29, 2019 Help!! I've been looking on the maps for Idle but can't find it. There are several bits and bobs I want to buy for Nyx, and good boat stalls are hard to find. Please advise! Quote Link to comment Share on other sites More sharing options...
grendel Posted August 29, 2019 Share Posted August 29, 2019 Near Bradford MM 1 Quote Link to comment Share on other sites More sharing options...
MauriceMynah Posted August 29, 2019 Share Posted August 29, 2019 That figures. Idle and North country do seem to go together. Thinks, Time to go hide. :-) 1 Quote Link to comment Share on other sites More sharing options...
grendel Posted August 29, 2019 Share Posted August 29, 2019 2 hours ago, MauriceMynah said: That figures. Idle and North country do seem to go together. Thinks, Time to go hide. :-) you could even idle moor. Quote Link to comment Share on other sites More sharing options...
MauriceMynah Posted August 29, 2019 Share Posted August 29, 2019 6 minutes ago, grendel said: you could even idle moor. Bet I couldn't.......... though I will try Quote Link to comment Share on other sites More sharing options...
VetChugger Posted August 29, 2019 Share Posted August 29, 2019 Idle near Bradford was the home of the well regarded hifi manufacturers Leak! No doubt about the humour possibilities there! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.