Outboard trouble

Hi there,
I hope someone can help me. I have a 2 stroke 40hp Yamaha engine on the back of our boat. We were out at the weekend and it was running fine. Went out last night and the only thing different was that we put in new fuel. The mix was right. The problem is the power has dropped to about 50% of what it should be. Coming back from the Rockabill at the weekend, we were hitting 22mph, last night it was 10mph. The odd time the engine will kind of jump or thump. Could there be sand clogging the prop, clogged filters? Any ideas anyone??!!
JD.

Ok, Simple stuff first and I dont mean to sound insulting either with any of these suggestions for you as I have discovered most of these the hard way myself....

First off, have you opened the valve on the fuel tank?

Check the actual fuel line and connections from Tank to outboard, was there anything resting on it, any kinks or anything else that would restrict fuel flow?

Check your fuel filter and clean if necessary.

Are your leads from distributor to Spark plugs firmly and securely on?

Check your plugs, if they are overly sooty or oily, your mix could have too much oil in it. Clean them, check the gap on them and try again. If you have a spare set, try them.

Has any water made its way into the tank at all? Empty that mix out, make sure tank is thoroughly clean and dry, put in some fresh stuff and try again.

If your operating with remote controls, make sure that your throttle lever inside the engine is not sticking and that your cables are secured properly at the outboard and at your remote box. Sometimes, depending on the setup, they can jump out from their housing and you cant get the full "push pull" action on them.

After that my limited knowledge is exhausted and its time for the pros.... :D Hopefully its something simple like a loose lead onto one of the plugs. It sounds like you're off a cylinder and that jump or thump is a backfire or something going on. Start off with the plugs and leads and see how you go. If its not that, you may need a new coil or worst case scenario, you've blown a cylinder (unlikely....thankfully) Is she pumping water etc OK?

Hi PeteKD,
Many thanks for your reply. I'm a complete novice here, so no insult taken to any of your suggestions, keep them coming!

Its pumping water fine, no issues there. Checked the leads and no blockages or kinks etc. The only thing I did notice that after sitting with the engine off after running, there was still a bit of squeeza left in the fuel bulb. No water has got into the tank and I did open the valve on the fuel tank. Remote controls are fine.

I will change/clean the plugs and see how I get on. Is the air/fuel filter change/clean an easy enough job on an outboard?
Thanks again,
JD.

It depends on the outboard to be honest Jay, follow the fuel line from where you attach it to the engine and you should come across, a glass bubble type thingie with a filter inside it or attached to it. Have a look at that. Definitely sounds like you're off a plug though from what you were saying and I'd be more inclined to concentrate around that area. I'm no expert, but thats what it sounds like. I wouldnt put too much store in there still being a bit of squeeze left in the bulb on the fuel line, thats normal. How old is your Yam?

You know what I'm going to say............ :lol:

No seriously, try it. A quick squirt will solve many evils on your outboard. :D

Aye, WD40 and cable ties, wouldnt go to sea without them. A blast around the plugs, into the leads etc will do no harm at all either.

Pete/Tanglerat,

Many thanks for this. I'm going to replace the plugs. You reckon its ok to WD40 everywhere? So undo all cables and pipes and WD40 them? What about filters?

I'm not too sure of the exact age of the engine but I reckon is about 15 years old.

JD.

So undo all cables and pipes and WD40 them

Noooooooooo!!!!!! Just the ends of the leads that go onto your plugs and anything else electrical looking around there. Dont start dismantling your fuel pipes and squirting WD40 down them and definitely dont start squirting your fuel filter full of WD40 either! WD40 displaces moisture and if their is any residual moisture lurking around there, it may be causing electrical problems resulting in one of your cylinders not firing properly etc.

Ok Pete! I will try what you have said. The weather is supposed to be good this weekend so there is no way I won't be out on the water!!
Will let you know how I got on.
JD.

Best of luck mate.

Just coming accross this thread now.... Sound advice Pete...... I would be looking at the plugs as well.

After replacing the plugs Jay, check them after your first outing. If there is a lot of fouling on one of them you might have done a piston ring and are loosing some compression in the cylinder. This is a fairly simple fix, but could cost you a few quid.

Kev

Dear All,

You will be glad to know that we replaced the plugs, used WD40 on the leads and did some general clean up on the engine of "Draiocht Beag" and she was firing on all cylinders yesterday! We clocked ourselves doing 25mph across not calm but not overly choppy water yesterday. It took us about 12 minutes to get to the Rockabill from Skerries. Just need to improve the fishing skills now!!!

Many thanks to all and sundry for your help.

JD.

Job's a good'un. WD40, don't leave home without it! :D