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Old 03-02-2014, 12:56   #16
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Re: HELP: Yamaha 4hp outboard engine

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Originally Posted by beneteau-500 View Post
I have the same 4hp engine one thing with these engines for some unknown reason is the float valve jams fully open indicating fuel bowel chamber is full i found by slightly moving the float pin over the one that the float swings on one way fixed the prob and the second prob it might be is the kill switch one way of testing this is to disconnect the white wire near spark plug and see if she starts
I would second this and from what you were describing.

When you remove the drain on the bottom of the bowl, you should get more than a little bit of gas coming out, especially if the fuel line is still attached.

If you carefully remove the float bowl, you can check the needle valve goes in and out when you raise the float up and down. blow in the fuel intake and lower the float down and you should hear air come through. Spray with B12 or other carb and choke cleaner while the bowl is in the down position and put back together.

Put your hand over the intake and pull once in order to pull gas into the bowl. Next choke it and start.

Use Seafoam in your tank. It does a good job at liquefying gunk.
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Old 03-02-2014, 14:21   #17
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Re: HELP: Yamaha 4hp outboard engine

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Thanks for all your hints!!
Yes, it was very old fuel, but I don't think with Ethanol. Anyway I have replaced it by new fuel and the engine still won't run.
I found that the carbs 'cup' did not even get wet anymore.
I found a nice guy here in the bay, boatbuilder, who knows a lot about engines and he helped me to get this solved: The inlet valve into the card which gets actuated by the float was blocked by a little tiny black piece dirt. This must have ended up there after the reassembly of the engine in the service.
Now its all up and running again and - may be even more important - I will have no problems to solve such issues by my own in future because I have learned a lot!
Congratulations!! I'm glad you got that one solved and I'll bet you're happy it is pushing you around again.

That's all it takes is just a little bit of dirt in there.

Be certain you don't let any ethanol fuel stay in your carb. It'll gum it up much worse than the little spec of dirt.
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Old 22-02-2014, 14:02   #18
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Re: HELP: Yamaha 4hp outboard engine

Be very careful with the gas and tank. I have a 8 hp 4 stroke, every spring I have to get the carb cleaned, a small piece of dirt or hose gets in, and the low speed jet is VERY tiny. It plugs just from thinking of it. I have double in-line filters, still plugging. Took extra precautions last fall, will see in a few months if prudent.
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Old 22-02-2014, 20:57   #19
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Re: HELP: Yamaha 4hp outboard engine

That black piece of dirt, you saw could very possibly not be black dirt. The ethanol in the gasoline breaks down the inside of the hose and it begins to fall apart in little pieces. Those pieces flow downstream. That might be what you found, which means you need a new hose.
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Old 23-02-2014, 11:36   #20
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Re: HELP: Yamaha 4hp outboard engine

Oh, interesting input! Thanks!
Right now it works fine! I had already exchanged some hose sections as they broke so easily.
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Old 24-07-2019, 01:08   #21
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Re: HELP: Yamaha 4hp outboard engine

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Originally Posted by beneteau-500 View Post
I have the same 4hp engine one thing with these engines for some unknown reason is the float valve jams fully open indicating fuel bowel chamber is full i found by slightly moving the float pin over the one that the float swings on one way fixed the prob and the second prob it might be is the kill switch one way of testing this is to disconnect the white wire near spark plug and see if she starts
Hi, I believe I have a sticking float, can you go into more detail on how you fixed the problem,

Thanks
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Old 08-08-2019, 21:26   #22
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Re: HELP: Yamaha 4hp outboard engine

After spending $100’s on it, I fixed it by buying a Lehr propane 5HP. Jets get clogged even with non-ethanol fuel.
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Old 11-08-2019, 10:27   #23
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Re: HELP: Yamaha 4hp outboard engine

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After spending $100’s on it, I fixed it by buying a Lehr propane 5HP. Jets get clogged even with non-ethanol fuel.
I'll take it.
If you happen to come to FL. bring it along.
If not, on the way to Utah in late Sept. (maybe) I can stop by and pick it up.
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Old 11-08-2019, 13:46   #24
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Re: HELP: Yamaha 4hp outboard engine

Got rid of it in 2014. Was a great engine up until,the gas changed, after that, couldn’t keep it running. If I still had it, it would be yous
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Old 11-08-2019, 14:03   #25
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Re: HELP: Yamaha 4hp outboard engine

Heh.
I had no idea the thread was that old.
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Old 11-08-2019, 15:27   #26
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HELP: Yamaha 4hp outboard engine

Thread isn’t that old, but I bought my Yamaha 4 HP, 4 stroke winter of 2004 at the boat show">Miami Boat Show along with an Avon dinghy., after I bought my new H356 in March of 2003, commissioned in May 2003. It was a great engine for several years, then the gas went south when gas regulations screwed it up. We took our boat to Florida on a six month cruise from Kentucky Lake in 2013-14. I had it serviced two weeks before I left. Worked at mile 76 on the Tenn-Tom the. A week later at Big Lagoon while anchored there, wouldn’t run. Got the carburetor cleaned with Ultrsound by established dealer in in Panama City. He’s the one that alerted me to,the gas issue. He said it was the gas. Put fresh gas in, fresh gas in 2 gallon tank and crossed the gulf, 1 week later at Gulfport Marina on GICW, wouldn’t startAfter that I had carbs cleaned, replaced twice - once went less than a month while cruising. Nothing worse than a dinghy motor that won’t run when you are cruising. The jets are small as hairs. Used non- ethanol gas - still wouldn’t run. Got to Punta Gorda, went to large Yamaha Dealer in Port Charlotte and put new carb on, then took it and left on consignment where I bought a 5hp Lehr propane and after a few initial tuning problems, started every time. No comparison in the reliability.

Consigned had it two weeks, guy walked In to buy it and it would ‘t start - lost the sale. Put a new fuel pump on it never sold it. Left in Fla and saved hundreds since.

I wish you luck if you buy one, but I had nothing but bad luck with mine. The jets are too small as the gas crystallizes in the jets. You can run it til it quits - which I did every time - still has enough residual to crystallize. The larger over 8 hp Yamahas have larger carb jets and don’t have as much of a problem, but all the small 4 strokes do.
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