What more can I do?? 70hp Mercury starting/running problems

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Diver503562

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I have a 1982 Mercury 70hp outboard enginge, regnr 9046840. For some time I had to be gentle on speeding up, otherwise the engine would die. Some weeks ago, it stoped even when I took it slow.. Now I can only start it using some kind of starting spray in the carburators. I have new gasoline on it, put in new plugs, and I have cleaned the carburators. Now I don't know what more to do. Also: When I get it startet, it runs pretty fine in neutral, but when placed in gear, it stops when given throttle.
 

JB

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Re: What more can I do?? 70hp Mercury starting/running problems

Howdy, Diver.<br /><br />Go to www.outboardrepairs.com and look up power loss.<br /><br />Good advice there.<br /><br />Good luck. :)
 

Diver503562

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Re: What more can I do?? 70hp Mercury starting/running problems

Thanks for your reply JB! <br /><br />Have tried that web-site already.. That is were I got the tip of cleaning the carburatores and put in new gas.<br />But I will keep on reading thru all of them..<br /><br />I have talked to a Mercury shop here in Norway, and they told me to check the carburators again. When I mentioned I have problems starting it without starting spray they didn't now what advice to give me... And they don't have time to take a look at it untill the start of August..
 

sharkcat

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Re: What more can I do?? 70hp Mercury starting/running problems

sounds like its not getting fuel.check fuel lines,pick up in tank,tank breather,filters for blockages & replace or clean as reqd.GET A MANUAL it will pay for itself in no time.Strip carbs ,clean & reset float levels etc(the manual will show you how)reassemble & while you are at it it wouldnt hurt to replace the plugs.Then do a link & synch & adjust carbs as per the manual & Ill bet your troubles will be gone.I know you have already cleaned the carbs but if you have a dirty fuel system the carbs may be dirty again.Hope this helps. :)
 

Diver503562

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Re: What more can I do?? 70hp Mercury starting/running problems

Now I have changed the diaphragm in the fuelpump, I've put in fresh fuel, changed gas tank, primer pump, fuel hose, cleaned the carbs again, changed inlet needle seat, adjustet carbs as pr manual, and still the engine will not run in gear! <br /><br />It almost worked one day?! For maybe five minutes I had it running at full speed in forward gear. Then it would slow down, and die. When trying to start it again right away, I could hardly get it to turn. The flyweel was almost stuck for a little while.. <br /><br />When it started again, it would only go very slow in forward gear. When giving some more throttle, it would die out again..<br /><br />Now it won't go fast forward at all...<br /><br />I know it isn't overheating, because there is a steady line coming out of the so called "****-hole" (Can anyone also tell me the correct name for this? )<br /><br />Any more help would be highly appreciated!
 

Diver503562

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Re: What more can I do?? 70hp Mercury starting/running problems

Ops.. forgot this:<br />I tried to spray starting gas in the carbs when it almost dies in forward gear.. That didn't help at all, just made it go even poorer..
 

Fouled Plug

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Re: What more can I do?? 70hp Mercury starting/running problems

Are you getting good spark on all plugs? What compression readings do you have? Almost sounds like not all cylinders are firing.
 

Diver503562

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Re: What more can I do?? 70hp Mercury starting/running problems

I haven't checked compression.. But I'm getting sparks on all plugs..
 

Diver503562

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Re: What more can I do?? 70hp Mercury starting/running problems

Any suggestions to what I might try?<br />I have described my problem to two mechanics here in Norway, and they told me I had done what they would do.. Pluss they would charge me about 85 US$ pr/hour for doing it...
 

sharkcat

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Re: What more can I do?? 70hp Mercury starting/running problems

Have you checked the reed valves if they are failing/leaking they can cause all sorts of problems.Also check the compression you may have one or more cylinders with low compression.
 

Diver503562

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Re: What more can I do?? 70hp Mercury starting/running problems

I'm not sure what the reed valves are.. Are those the ones adjusting idle mixture in the carbs?
 

sharkcat

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Re: What more can I do?? 70hp Mercury starting/running problems

Hi Diver reed valves are between the carbs & the crankcase they open & close with the change in pressure in the crankcase caused by the pistons going up & down.However I have been reading old posts about problems like yours one obscure cause was the low speed windings in the stator had gone legs up.Worth checking,your manual will tell you how. :)
 

Diver503562

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Re: What more can I do?? 70hp Mercury starting/running problems

Thanks for the tips, Sharkcat. I will try to get some work done this weekend. I'm going to check the stator(s?) and compression. I read about the reed valves last night.. Seems like a difficult job checking them? Need to disassemble the entire power head? If the stator checks out ok, I will take a look at the reed valves. Hope this helps, because I want to go water skiing! :) Have been looking forward to that the entire winter season!
 

Diver503562

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Re: What more can I do?? 70hp Mercury starting/running problems

I checked the stator now, and it seems to be working fine, according to the manual. I also checked the rectifier but the ohmmeter readings are not as specified in the manual, and also the stator lead connected to terminal C on the rectifier was melted.. Could this be why I'm having trouble? <br /><br />And also: Can I just replace the rectifier, or is there something else that is wrong, since the wire melted?
 

Diver503562

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Re: What more can I do?? 70hp Mercury starting/running problems

Okey.. I changed the rectifier (I had to pay 125 US$ for that little thing! Would it be cheaper to have items sent from the US maybe??) but it didn't help.. I checked the compression, and the readings were as follows from top to bottom: 0, 125, 115... This means I have to rebuild the entire engine? Does anyone know if this is a difficult thing to do, or does it just take some time? <br /><br />OR can I fix this without a total rebuild?
 

Yepblaze

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Re: What more can I do?? 70hp Mercury starting/running problems

Pull number one piston out and inspect for damage.
 

Diver503562

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Re: What more can I do?? 70hp Mercury starting/running problems

But what about the compression readings? The upper cylinder had zero, while the middle had 125 and the lower 115..
 
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Re: What more can I do?? 70hp Mercury starting/running problems

Diver;<br /><br />If you have one cylinder with 0 compression you will need to rebuild. You may have burnt a hole in a piston. You will also need to find out why the cylinder went bad (i.e. was it running lean from carburetor/jet being blocked) otherwise the same thing is likely to happen again after the rebuild.<br /><br />Make sure you clean out all the old gas and crud from ALL the fuel lines. This includes; fuel tank to motor line, and line/lines to and from fuel pump and the fuel pump screen itself.<br /><br />Good luck
 

sharkcat

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Re: What more can I do?? 70hp Mercury starting/running problems

Hi Diver sorry I havent been able to get on line for a couple of days have been busy at work,it looks like you have found a problem.I would hazard a guess & say that youll find a broken reed on no.1 cylinder & probably a hole in the piston or broken rings hopefully it wont have damaged the bore.Two strokes dont like running lean.Strip the powerhead & let us know what you find.Dont be in too much of a hurry to solve problems by buying replacement parts as it will cost you alot of money.The rectifier has nothing to do with the ignition on your motor.Possibly there was a problem with it but it wouldnt have caused the problems you were having.GET A MANUAL.good luck :)
 
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