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2003 NSF99A Nissan shuts down at high speeds

T

teeitup007

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"Hey guys and gals, got a 9.9

"Hey guys and gals, got a 9.9 horse nissan that runs great while going slow in the marina but when I try to get it up to speed on the lake it quits after about 10 seconds. The primer bulb seems to lose its firmness no matter the speed but only quits when trying to go faster than no wake speeds. Changed the oil, oil filter, fuel filter, plugs (which were original to the motor and pretty black), running clean gas, etc... Would you start at the fuel pump or let me guess clean the carb? Thanks"
 
"In this case the prime bulb i

"In this case the prime bulb is telling you something. If it is going soft, theory tells you that the problem is between the fuel pump and fuel tank:

Bad bulb
Bad gas line
Bad fuel connector
Bad fuel pump

IE. You are sucking air into the line.

That's theory....It's probably going to be the carb though
"
 
"not saying that this wouldn&#

"not saying that this wouldn't be the problem but the tank, line, bulb, and connectors are all brand spankin new. the pump is original to the motor. at what connection point would I be sucking air... after the bulb most likely or before it? or would it go soft either way? also, is teflon tape necessary on the connectors? my "west marine" guy told me it was a good idea."
 
"New only means new, it doesn&

"New only means new, it doesn't mean not bad. There is a one way valve in the bulb that can be bad, any pin hole, loose connection point or a bad fuel pump diaphragm. If the bulb is 100% perfect the problem would lie between the bulb and the carb....Again, that's theory. Reality has a habit of not fitting theoretical models. Teflon tape is unnecessary 999 out of 1000 times, but it doesn't hurt a thing to use it."
 
"Tried a completely different

"Tried a completely different tank, hose, and bulb with the same results. Weak bulb after a minute or so of cruising. Changing out the fuel pump today."
 
Worked fine for a day with new

Worked fine for a day with new fuel pump... Then nothing. Wouldn't even start. Took the carb off but am not sure what gets cleaned and what to take off. All rubber parts I removed but not sure about the float or any other small parts. Anyone got a suggestion? Any carb cleaner better than the other.
 
""Worked fine for a day wi

""Worked fine for a day with new fuel pump"

Clean the carb in any one gallon can of carburetor cleaner. The float is plastic so you would not put it in carb cleaner.

Your symptoms, what you have done to correct it, and what the results have been, don't add up. That happens all the time. Unfortunately outboard repair is only 50% what makes sense. The other 50% is guess work and experience and blind luck, so I would suggest you start over again. Take a hard look at the fuel line and its connection points as well as the fuel itself."
 
"Ok, cleaned the caen for abou

"Ok, cleaned the caen for about 6 hours Sunday. Today, started right up but didn't have time to run it under load at high speeds. So the next question is... I ran the fuel out before leaving it at the dock and I noticed that the in line fuel filter is still full of fuel after the engine shuts down. Is it supposed to be? And also the new bulb on the gas line didn't stay hard while I ran it.it was firm but not hard and I could squeeze it every couple of minutes to get it full again. Is that normal?"
 
"Yes on the first one and the

"Yes on the first one and the second is a yes/no/maybe. Some bulbs stay rock hard, some get fairly soft, but the majority seem to settle in at a firmness level that I would describe as unripened banana"
 
"ok, I am really close to sell

"ok, I am really close to selling this thing while I can still tank test it. Back to square one. Bulb goes limp while running in gear and I have to keep pumping it to kep it firm but I am afraid I am flooding the engine.?. Engine shuts down under load about 10-15 seconds after acceleration. Won't start for about ten minutes after while floating and cursing on the lake about how Nissan sucks. Cleaned the carb AGAIN and got the same result. Once it dried and I got it restarted and while it was running at idle speed I pulled each one of the plugs off of the engine just to see what would happen. The top plug after I pulled it off made the engine run a little different not much but a noticeable difference. As for the bottom plug...once I pulled it out the engine ran for 3-5 seconds then shut down. tried it again and again with the same results. Not sure if that means anything. I am almost out of options other than sell it off to make it someone elses problem. I would rather be boating than wrenching."
 
I think you have reached the e

I think you have reached the end of what your ability allows you to do. It's time to take it into a dealer and let them determine what is wrong.
 
"Nope. That means that the bot

"Nope. That means that the bottom cylinder is the only one that is working. At this point you need a service manual to get the test procedures for the ignition system to eliminate that system as the source of the problem....Or, take it into a dealer. I would urge you to do the latter as I think we have reached the limit of what a novice can do in a cost effective manner."
 
"Don't know if this will h

"Don't know if this will help in your situation, but, I cleaned the carb on my 9.9 a dozen times, and still had shut down problems. What worked, and I don't see mentioned here is: after soaking in carb cleaner for 10 minutes to soften grime, I poked every hole (some are very small) I could see with a wire (small 4" piece of guitar string works),continued to soak, then blew it out with an air compressor. This, after I threatened to throw the motor overboard, or use it as an anchor.Now, I wouldn't part with the heavy sucker. Hope this helps somebody.

Steve"
 
"the electric choke is stuck c

"the electric choke is stuck closed, that is why it stalls when given
gas, my 15 hp is doing the same thing. I can see that the choke
is closed but I do not want to force it open until I find out how
so I don't damage it'"
 
"tim, taking off the cover of

"tim, taking off the cover of the motor you will see the carb. if like
mine you will see wire going to the top of the carb. To look
at the choke you must take apart the plastic intake of the carb.
then you can look at the flapper on the intake of the carb.if it
is closed or mostly closed that is your problem.
and right now I am trying to find out how to open the chock with
out hurting anything."
 
is that the circular brass pie

is that the circular brass piece that has a silver bar through it to regulate the amount of air going into the engine? If so mine moves freely. I have taken my carb off before and the plastic inntake attached to the carb is just that... a plastic piece that has a screen on it. Not sure if yours has something else associated with the plastic air intake.
 
The choke operates via the aut

The choke operates via the auto-by-pass sender located on the top of the carb...It wouldn't have anything to do with an engine running on one cylinder.
 
"When I went back up to our ca

"When I went back up to our cabin I took the carb abart and looked
at where the choke should be and saw that it was injection, but it
back together. I tapped on the bottom of the carb like I had done
several times before, and the engine started running normal at
high speeds."
 
"My motor started not running

"My motor started not running at full throttle again, I took off the carb
took off the float cover, I saw that a rubber plug was hanging
loose, then it dropped off. I tightly put it back in the port hole
it came out of, put carb back on. And it now runs perfectly.
Why would Nissan put a rubber plug in a chamber where gasoline
exists. I hope this will help solve other peoples problems. Roly"
 
"They have done for it over 30

"They have done for it over 30 years without a problem. I can't think of any case, other than yours, where the plug was improperly put in and then came back out."
 
"Dont know if this will help o

"Dont know if this will help or even if it applies but, my 25 hp nissan was doing something similar to this and what i found was the plastic intake air ram (not sure of term) where it bolts to the carb had broken around the bolt hole and a piece of the plastic was sticking into the throat and catching the choke butterfly and not letting it open. bought a new one and the new one was cracked and starting to warp also. returned it and got another one that was fine and that fixed that problem."
 
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