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Old 19 August 2010, 11:22   #1
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problem with Yamaha 4 hp fourstroke

I have a problem just developed when the tank ran dry , the engine will start but when I push in the choke it cuts out. I dont know my way around an engine , does anyone have an idea what the problem might be?
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Old 19 August 2010, 12:33   #2
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Start by stripping and cleaning the carb, may have sucked up some crap when you ran dry...
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Old 19 August 2010, 18:08   #3
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Start by stripping and cleaning the carb, may have sucked up some crap when you ran dry...
Yep, sounds like you've got a blocked jet.

It's worth putting a fuel filter in if it doesn't have one.
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Old 19 August 2010, 21:50   #4
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I had a similar problem with my old Johnson aux, see here Johnson 6hp problems as above, poo in the fuel which is probably what your problem is as the bottom of the tank will have got stirred up.

As I found out after a bit of head-scratching there are usually several jets in the carb not necessarily all going in from the same direction, the obvious one on mine was not the blocked one.
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Old 20 August 2010, 02:41   #5
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4hp

is your VENT on top of the tank unscrewed
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Old 20 August 2010, 04:55   #6
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Engine fault

Blocked idle jet.

An easy job to repair if you are confident with stripping the carb, otherwise take it in to a dealer. When was it last serviced? Might be an idea to get it serviced at the same time, it's not much on these small engines, I was quoted 45.
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Old 20 August 2010, 06:51   #7
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Thanks for the replies , I was having a look on youtube to see how it was done has anyone any step by step pictures or diagrams, I would like to learn to do it so if it happens again I could sort it
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Old 20 August 2010, 14:15   #8
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Just to let you know , I had a go at taking the carb off and cleaning it out, then re assembly , started the engine and its running fine now. Im glad I didnt bring it to a mechanic now and have learned how to fix it again. I could do with replacing the impellor on my main engine and was wondering if I could handle it, do I need to change the thermostat at the same time, has anyone any diagrams?
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Old 20 August 2010, 14:22   #9
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Isn't a Yam 4 a re-badged Jetmarine?
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Old 20 August 2010, 20:27   #10
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Just to let you know , I had a go at taking the carb off and cleaning it out, then re assembly , started the engine and its running fine now. Im glad I didnt bring it to a mechanic now and have learned how to fix it again.
It's one of those things that sounds quite daunting until you try it and you then find that with a few tools, some compressed air and a bit of common sense it is actually quite easy to do and you feel dead chuffed when you sort it out
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