40 Horse Nissan has no power, sputters

jason389

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Joined
May 15, 2005
Messages
27
40 Horse Nissan (about 10 years old) idles fine, but won't plane off and lacks power. Not too sure about the carb on this one. It has an idle adjust and what appears to be the main jet adjustment. I turned it all the way in and worked out, no luck. I even adjusted the carb while my brother drove the boat, still now power. It appears to be getting too much fuel (spark plugs black). Any suggestions? I don't have a manual for this engine.
 

TOHATSU GURU

Admiral
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Jul 22, 2004
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6,164
Re: 40 Horse Nissan has no power, sputters

Check for fire, compression, replace the spark plugs and plan on cleaning the carb.
 

jason389

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May 15, 2005
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Re: 40 Horse Nissan has no power, sputters

Has fire, has compression, already cleaned the carb.
 

TOHATSU GURU

Admiral
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Re: 40 Horse Nissan has no power, sputters

If you have fire and compression that only leaves the fuel system as the problem. Anything from the fuel itself to a chipped reed could be the problem. You are just going to have to check everything from the fuel tank back.
 

jason389

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Re: 40 Horse Nissan has no power, sputters

Motor getting plenty of fuel, I'm thinking that ignition system is breaking down under a load. Is there any way to test this?
 

jason389

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May 15, 2005
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Re: 40 Horse Nissan has no power, sputters

Rebuilt the carb, float set, reed valves look good, new fuel lines/ tank. Motor still stumbles and lacks power, sputters, won't plane off, spark plugs black/ wet with gas. The main jet screw is out 1/4 turn. Has anyone else had this problem with this motor? I understand it's common.
 

TOHATSU GURU

Admiral
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Jul 22, 2004
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6,164
Re: 40 Horse Nissan has no power, sputters

You need a service manual to get the trouble shooting procedure for the ignition system. The problem you are having is common to all internal combustion engines.
 

ziemann

Chief Petty Officer
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Apr 28, 2004
Messages
584
Re: 40 Horse Nissan has no power, sputters

Jason, as Elvin said this is common to all outboards. There is nothing in the Nissan 40 that predisposes it to this kind of problem. In fact, quite the opposite is true. It is a pretty forgiving engine. <br /><br />Altho it is certainly possible that you have an ignition issue, I still am leaning toward crud in the carbs even though you cleaned them. I would be willing to place money that they need to be pulled and soaked some more then blown out. As you know, old fuel sitting in the bowl or any piece of crap can create this problem. And it only takes a tiny piece of crud to drive you nuts. <br /><br />If the reeds are fine and there are new fuel lines (I am guessing you replaced them for a reason) we are down to the pickup in the fuel tank or something with the carbs, or bad fuel. Sorry to state the obvious......and you already knew the answer. <br /><br />Compression you checked. Spark you checked. So odds are, we know where to narrow this down. <br /><br />Contact Elvin for a service manual. They are only about $20 and he will be able to get one to you in just a few days. A service manual since it is so cheap, is an invaluable tool. <br /><br />Good luck and let us know how it turns out!
 

crab bait

Captain
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Feb 5, 2002
Messages
3,831
Re: 40 Horse Nissan has no power, sputters

there's this gas additive that's an enzyme.. it's buy a major brand name that escapes me..<br /><br />drain the carbs again ... take a yogurt container ..scissor the side walls down so you have a one inch cup..<br /><br />hold under drain plug an look for crud.. ( the bottom you can't .. just let it drain.)<br /><br />then somehow fill the carbs with the enzyme an let sit for days.. <br /><br />drain .. an add enzyme to gas an run..
 

jason389

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May 15, 2005
Messages
27
Re: 40 Horse Nissan has no power, sputters

Got the manual, will check carb again tomorrow.
 
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