Nissan outboard loses power after operating at full power after about a minute

[hurricane1983]

40hp 2 stroke 3 cylinder Nissan loses power after running full throttle after about a minute. I have cleaned all 3 carbs twice, put in kits, replaced fuel hoses on the engine and from the tank along with the bulb, changed filter screen and replaced the fuel pump. This is what happens, it will idle all day, run at medium throttle till the cows come home but at full throttle it will bogg down, I can squeeze the bulb one time and it will pick back up, I have a firm bulb when I squeeze it, it will run for a while and bogg down agian. I have checked the vent as well and the pickup tube in the tank. any suggestions

 

[Jake Windemere]

Re: Nissan outboard loses power after operating at full power after about a minute

My guess, bad tank or bad fuel line. Swap 'em out with good ones first.

Try this thread:

http://forums.iboats.com/showthread.php?t=329782

 

[rogerwa]

Re: Nissan outboard loses power after operating at full power after about a minute

Not to be too obvious but your symptoms indicate a fuel starvation problem. You are either sucking air, have a fuel pump that connot keep up, have a restriction (collapsing hose, sucking junk into the fileter screen/dirty tank), or even a carb float problem.

Can you try a different tank and hose? That would eliminate one portion of the system.

 

[hurricane1983]

Re: Nissan outboard loses power after operating at full power after about a minute

I have replaced the tank and hose and fuel pump, also replaced fuel lines on the motor. What else can it be?

 

[pvanv]

Re: Nissan outboard loses power after operating at full power after about a minute

Definitely sounds like a fuel starvation issue. Either you are drawing air, or not drawing fuel. Seems you have changed out all sorts of stuff without actual troubleshooting -- a rather expensive way to do a repair.

Verify or replace the filter. Confirm good fuel quality. You can mount or hold the tank above the motor for testing, to let gravity assist in fuel delivery.

 

[qwackhead]

Re: Nissan outboard loses power after operating at full power after about a minute

are you sure you dont have a galded piston i had a 25 do the same thing and it had a galded piston the tattle tale will still pee on a nissan but you may have a cooling passage stoped up it took three times before we found mine lots of compressed air blow through all the head ports good.

 

[redfish1940]

Re: Nissan outboard loses power after operating at full power after about a minute

Did you ever find out what your problem was?. I have the same motor and having the same problem . Mine will stall out alltogerher when I push in the choke .I think it a electrical problem.
O ya I done everything you done including draining the fual tank.
thanks

 

[TOHATSU GURU]

Re: Nissan outboard loses power after operating at full power after about a minute

"I can squeeze the bulb one time and it will pick back up"

If you have the same symptom as him, then you probably have the same problem....A fuel system issue. You will have to troubleshoot the system to determine the problem or you can randomly replace parts until you guess right. First guess would the fuel pump on # 3 carburetor.

 

[redfish1940]

Re: Nissan outboard loses power after operating at full power after about a minute

When i squeaze the ball nothing happens . When I pull off #1 or 2 pug wires the motor changes. If I pulll off #3 plug wire nothing happens. I swaped coils around and still # 3 nothing changes it seems to run only two cylinders.1&2 and the # 3 plug Is wet. there is only one fuel pump to all three carbs. Right.?
Is there any way for a shop check the CDI.
thanks

 

[TOHATSU GURU]

Re: Nissan outboard loses power after operating at full power after about a minute

Yes and the test procedures can be found in your service manual.

 

[redfish1940]

Re: Nissan outboard loses power after operating at full power after about a minute

Thanks I have one on the way

 

[redfish1940]

Re: Nissan outboard loses power after operating at full power after about a minute

Im back.with another question. before my servise manual comes Darn hallidays have slowed it down.
I just noticed on the back cylinder head cover there is a plug missing (not spark plug) it screws in and the parts digram just call it a pug.
I was woundering whats it for and does it need to be in.
maybe thats problem?

 

[pvanv]

Re: Nissan outboard loses power after operating at full power after about a minute

redfish,

Your problem seems different than what hurricane's was. Honestly, this should be in a new post, but since it has already been hijacked, let's proceed.

Please describe the precise model of your motor (haven't seen it listed in any of the posts), and maybe we can look at our copies of the parts catalogs to identify what you are talking about. THEN, after making sure we're all onthe same page, we can probably help.

 

[redfish1940]

Re: Nissan outboard loses power after operating at full power after about a minute

You are righi I should have started a new post. I started off just wanting to know I hurricane ever found out what his problem was. But I never heard back from him.
I sure wish my manual would come.

I motor is a 2005 tohatsu M40D2 I was told the are same motor parts. the pug I was talking about # is 3b70140 found it online.

thank you and everybody else for responding. I tinker with mine and other friends motors.
but the one got me stumped. Thanks again

 

[pvanv]

Re: Nissan outboard loses power after operating at full power after about a minute

OK, cool, M40D2...

If you're talking about that 3B7-01046-0 plug on page 8 of the scanned parts catalog from Elvin's Internet Outboards site, that should not affect the spark to any cylinder.

If you don't notice any RPM drop when disconnecting the plug wire from #3 cylinder, that of course points to the faulty cylinder... if that spark plug comes up wet, it's likely it isn't getting spark (though it would also be possible to be getting tons of fuel, which won't ignite)...

If you have an old-school pencil-style inductive spark checker (with neon light in it), or for that matter, even an old style timing light, that would tell you if power is being delivered to that plug wire... since you changed coils, that seems to rule out the coil for #3... so one might suspect, all else being equal -- good compression, proper air/fuel mix, etc, that you either have a shorted plug, or are not getting a trigger to the #3 coil...

I would try a new plug (if you have one handy), or at least dry out the present plug, and maybe swap that plug to a known-working cylinder. Also see if you can test for spark... and see if maybe the float/needle in that carb is jammed open, dumping tons of fuel to that cylinder, which can't burn, as it's way too rich. Naturally, if that cylinder doesn't have compression, all bets are off.

Of course, once you get your service manual, you can pinpoint problems better, and see if the coil is being triggered by the CD.

Best in the New Year...

 

[redfish1940]

Re: Nissan outboard loses power after operating at full power after about a minute

The compression in all cylinders is good. I swapped pugs around also. no difference.I got three new ones orderd a Autozone they don't stock the ones I need. iI am going to buy a spark tester from them . I guess it would be better to test in the dark . to see the color of the flame I am getting spark it will shock me . I just dont know if its week or strong

I guess Ill pull the bottom carb. off again and check it .I haven't checked the bottom wreeds . I might have to do that If all else fails.

I never said In my post but this motor was taken to two differn't certified tohatsu shops.
First one put new fuel pump on .then had to take it back. then they took off the water seperator off and put on a little in line filter. That was baloney.
I put a water seperator back on. it was taken to another tohatsu shop they said it was the carb. linkage. baloney again. they dont water test it like I can.

 

[redfish1940]

Re: Nissan outboard loses power after operating at full power after about a minute

Well I gave up and took it to a dealer. lhey did everything I did over cost me alot of money. they had it three weeks and was as stumped as I was. fist they said it would only take a couple of days.same Ballony. finally called and said I had a blown head gaskit and was getting water in two cyinders.
So if anybody has the same problem check that first befor they spend your money for nothing
I had great commpression so I didn't think it was that

 

[pvanv]

Re: Nissan outboard loses power after operating at full power after about a minute

A water leak into a cylinder will typically "steam clean" that plug completely white, and is usually detected easily by that symptom. You didn't mention that symptom, and had good compression, so I can see why the shop didn't find that problem right away. Glad they got it fixed for you though.

 

[redfish1940]

Re: Nissan outboard loses power after operating at full power after about a minute

no none of the plugs were like you said they were all the same. alittle. wet and looked good
I thought it was rich fual. could have been water.??? .I try to fix them myself and do most of the time I do . I thought they would have the right testing equipment that I dont have. but they just guess like I do
thanks
certified mechanic ballona. Give me some old schooled had Knock mechanic.

 

[xanderman]

Re: Nissan outboard loses power after operating at full power after about a minute

A water leak into a cylinder will typically "steam clean" that plug completely white, and is usually detected easily by that symptom. You didn't mention that symptom, and had good compression, so I can see why the shop didn't find that problem right away. Glad they got it fixed for you though.

The OP mentioned he had swapped out the plugs and tested the cylinder with no change. This would have put the steam cleaned plug in a working cylinder and fouled it somewhat, and the plug with normal wear may have been in the other cylinder for a short duration due to it being only a test run.
Also, the leaking gasket might not have allowed water into the cylinders until it was under high pressure, so idling at the test time may not have cleaned it.