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brandenjg

mercury 15hp 4 stroke problem :'(

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Hi everyone, finally put the mercury on my boat today. Ran sweet in neutral but cut out when put into gear. Tried a few times and it kept doing the same thing. Now it wont even start in neutral. Have taken the spark plugs out and they were covered in fuel so cleaned then put back in. Still wont start. I've visually inspected prop, fuel lines, drive belt and sparkys and can't see whats wrong.

Must add that it is a great condition outboard that has been fully serviced by the company i bought it from a few weeks ago.

Any help and advice greatly appreciated as need to get the outboard up and running by friday.

Thanks in advance Branden :pirate

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Came from swansea via pallettways. I have a back to base warranty but would have to pay to send it back. Would take longer than a week.

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Checked the sparks and they're doing their job. The reason they were wet is because i was trying the pull start for ages. After cleaning them i left it an hour before trying again.

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Take the plugs out and pull the starter with the throttle held wide open

a few times to clear any excess fuel out of the cylinders.

Put back in and try to start without choke (if a manual one fitted).

When you checked the plug for sparking, was it a bright blue spark?

If yellow(ish), then something wrong with the ignition system.

Hope that helps.

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Aside from the problem of restarting with the wet plugs, and focusing back on the fact that it kept stalling when put in gear:

I would check for any stiffness in the transmission.

Remove both spark plugs, (for safety) then try turning the prop by hand, in neutral, reverse, and forwards.

With the plugs out, it will be stiffer in gear, but should still turn easily by hand.

Also, depending on how long the engine was ticking over, at this time of year with near zero temperatures, the very thick hypoid gear oil in the transmission would be very stiff when first turned, assuming the leg was in the water or a water tank. Until it's been turned a few times it's very heavy to turn, and could stop a slowly ticking over engine.

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I'm wondering if it's something to do with a safety switch of some sort? I'm no expert on outboards, but I think the larger ones tend to have some sort of mechanism to stop them being started in gear (my 8hp 2-stroke has a mechanical device for this so you cant pull the start cord when in gear)? If that was the case and it was faulty, could the mechanism be in the "in gear" position even when in neutral and therefore prevent starting by cutting the ignition, which then caused the flooding by repeated attempts to start..... just a thought.

Other thought is the kill cord switch dodgy?

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Just a stupid thought Brandon,as it is your 1st 4 stroke engine,you did not put mixed petrol in the tank which you would have run your 2 stroke on ,the engine would have probably started using the fuel in the carb,and cut out as the mixture got through.

Another issue could be the air valve is not allowing air into the fuel tank,if you tighten the cap too tight it will cause it to cut out under load,I had a similar problem with my first boat,I felt I right lemon when someone told me,not to tighten the filler cap too tight.

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Just a stupid thought Brandon,as it is your 1st 4 stroke engine,you did not put mixed petrol in the tank which you would have run your 2 stroke on ,the engine would have probably started using the fuel in the carb,and cut out as the mixture got through.

Another issue could be the air valve is not allowing air into the fuel tank,if you tighten the cap too tight it will cause it to cut out under load,I had a similar problem with my first boat,I felt I right lemon when someone told me,not to tighten the filler cap too tight.

I mean filler cap valve

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Thanks for the replies everyone, im heading down the boat for a few hours before work tomorrow so will try each bit of advice 1 by 1 until the darn thing works :grin: I'll let you know what the issue is once i know.

I had a thought that maybe my primer bulb was set the wrong way round so will check that aswell.

Waanty, i filled the new fuel tank with a fresh load of petty from the garage, which was annoying as i had 22l of pre mixed two stroke in the old tank.

Once again thanks forumites :clap

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As you have had it running im sure you havent forgotten it but........ Have you got your 'man over board' safety clip in, usually when a good engine suddenly wont fire its because thats not in! it does not answer your first problem, although the cold oil issue could if your tick over is very low.

Oh and i spotted a nice old Mercury on Gumtree, seller has same name as you, what are the chances?!

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UPDATE: Tried all the suggested things and none worked. Phoned the company i got the outboard from and after telling them what i tried they suggested that it must be fuel starvation and that it shouldn't be the pipes or filter as they all worked when they packed it for shipping. So they suggested that the pin in the carb must of jammed in transit. Sounds very likely as the engine was on it's side for a while and was layed on the other side by accident went put in the car to take down the boat. So the plan is to get my lazy brother to have a look as he's the carb man in the family. Hopefully he'll be awake when i finish work tonight at 7 :?

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UPDATE: Tried all the suggested things and none worked. Phoned the company i got the outboard from and after telling them what i tried they suggested that it must be fuel starvation and that it shouldn't be the pipes or filter as they all worked when they packed it for shipping. So they suggested that the pin in the carb must of jammed in transit. Sounds very likely as the engine was on it's side for a while and was layed on the other side by accident went put in the car to take down the boat. So the plan is to get my lazy brother to have a look as he's the carb man in the family. Hopefully he'll be awake when i finish work tonight at 7 :?

Did you lay it Carb side down? if so you may have filled it with oil, 4 strokes do not run too well if you do that!

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Hi everyone, finally put the mercury on my boat today. Ran sweet in neutral but cut out when put into gear. Tried a few times and it kept doing the same thing. Now it wont even start in neutral.

Sorry to sound pessimistic, but I can't see that it's a jammed throttle needle or carb float valve, if it "ran sweet in neutral - a few times".

You wouldn't have got a peep out of it if the needle was jammed.

Likewise if it had been laid on the wrong side and filled the carb with oil.

Fuel starvation seems much more likely.

Did you check if the primer bulb was the right way round, as you suspected ?

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Hallejuaha she runs :party2: Still unsure what the issue was. My dad and bro went down to try and get it running and did the same procedure i did, but where i gave the carb a little tap with a hammer, they hammered it for about 15seconds. Wd40 in the sparky holes and they got it up and running. After sitting in neutral for 20 mins they did a quick test of the gears while tied to land and they say it runs a dream. Tomorrow i'll be taking it for a lap around the island so hopefully it'll be all good.

Once again thanks for all the advice forumites :clap Branden

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A lap round the island ?

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A lap round the island ?
I took her out for a lap/spin/drive/ride/boat moving through water, around the island yesterday. Was great fun but very fast (idle set a bit high meaning mooring was interesting with the lowest speed being around 3mph). I opened the throttle for a few seconds to find the front of the boat lifting out of the water two guns which means planing could be a real possibility if it wern't for the speed limits.

Only issue was while attempting a 3 point turn for the first time in this boat, i went too slow into reverse and the engine cut out, one pull to get her up and running again though.

Incredibly quiet so much so that when it cut out i didn't hear any difference.

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Thanks, hopefully it'll be a trouble free season. Off to reedham tomorrow night so should be a fun trip :pirate

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The problem is back. Had about 60 miles use out of it, left it for a week and a half without running it. Yesterday went to take her out and it just would not start. Got the cowling off and when pumping the primer, fuel was squirting out of the top of the carb. Took it off, drained it, checked the float valve, tightened the rubber valve on top (which stopped the leak), put it all back together and it still won't start. I'm stuck as to what else to do. The only strange thing i noticed is that the steering doesn't sit straight so im wondering whether something or someone could of hit the outboard and thats why it won't start. The prop is all good in that free in neutral and stiff in gear.

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Sounds like it may be that the needle valve isn't seating properly which results in flooding the cylinders and squirting out the loose chamber when you primed.

Many of these valves have a small rubber skirt on the seal taper and they do wear. It could also be some muck in the fuel stopping it sealing.

Be very careful in tighening the chamber bowls as these carbs are very lightweight ali. Overtighening can easily strip the threads.

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