Nissan 5hp Starting Issues

[rythmman]

Here's a nice weekend brainteaser:

4-stroke very difficult to start from cold. There IS spark, forced in some gas, so basically left with compression. Tested it COLD and only got 40 psi.

EVENTUALLY used a power drill as an electric start, as my hands were becomming one big blister. Finally started, runs, but starts to stutter at high speeds.

Redid the compression test hot and got 50psi. The sparkplug also had a lot of black carbon on it.

It started more easily when hot.

Any ideas? Thanks.

 

[TOHATSU GURU]

Re: Nissan 5hp Starting Issues

Have the carburetor cleaned correctly and don't worry about the compression at this point.

 

[rythmman]

Re: Nissan 5hp Starting Issues

Seems to start ok now, still stuttering above half throttle and if I leave it at full throttle in neutral, it dies within 2mins.

 

[TOHATSU GURU]

Re: Nissan 5hp Starting Issues

"Have the carburetor cleaned correctly"

 

[rythmman]

Re: Nissan 5hp Starting Issues

Do i need to remove the air/gas screw? If so, what is the easiest way to remove the plug?

 

[TOHATSU GURU]

Re: Nissan 5hp Starting Issues

"Do i need to remove the air/gas screw"

Nope. There is no case where you would need to have access to the screw as the three hour dip in carburetor cleaner will clean that area for you.

 

[rythmman]

Re: Nissan 5hp Starting Issues

Thanks. So you're saying the screw never needs adjustment? I have cleaned it all and will test today.

 

[TOHATSU GURU]

Re: Nissan 5hp Starting Issues

Correct. The air mixture screw never needs to be touched. "Never" means practically never rather than an absolute. Say one out of 2000.

 

[rythmman]

Re: Nissan 5hp Starting Issues

Still very erratic. Idles, but dies in gear. Wandered if there may be a need to remove the 'freeze plug' on the side to further clean and if so, are these readily available as spares and do I need adhesive? I also suspect a float level issue.

 

[TOHATSU GURU]

Re: Nissan 5hp Starting Issues

How are you cleaning the carburetor? No adhesive is needed for anything and if the float is out of adjustment, just adjust it to level.

 

[rythmman]

Re: Nissan 5hp Starting Issues

Acetone. Don't know how to remove plastic bits to use something stronger. Do I need to remove the freeze/access plug on the side?

 

[TOHATSU GURU]

Re: Nissan 5hp Starting Issues

"Have the carburetor cleaned correctly"

"Nope. There is no case where you would need to have access to the screw as the three hour dip in carburetor cleaner will clean that area for you."

"The air mixture screw never needs to be touched"

You don't know what you are doing. Its that simple. Please take your engine into a dealer and let them clean the carburetor for you. I can tell you are determined to get to that air mixture screw in the misguided belief that you can miraculously make your carburetor work correctly. Unfortunately the problem is that you simply do not know how to clean a carburetor. Its nothing to be ashamed of. I don't know how to do a lot of things that other people can do in their sleep.

 

[rythmman]

Re: Nissan 5hp Starting Issues

I'm NOT talking about the air mixture; there is another plug in the center of the body which looks like it's been tampered with on my carb; hence my question. I do appreciate all the advice. Thanks.

 

[TOHATSU GURU]

Re: Nissan 5hp Starting Issues

Can you snap an image of the "plug" and post it or email it to me? There are removal jets inside the body, but they have screw heads and are clearly designed to be removed so I'm not sure if you are referring to a freeze plug that would not be removed or are just being thrown by something else.

 

[rythmman]

Re: Nissan 5hp Starting Issues

I have circled the 'plug' in red. Also, are ALL the plastic bits designed to be removed?

 

[TOHATSU GURU]

Re: Nissan 5hp Starting Issues

That is a non removable plug. The hard plastic bits on the outside of the carb remain on it while you do the three hour soak in carburetor cleaner. Carburetor cleaner is available from any auto parts store in a 1 or 5 gallon pail. Anything other than carburetor cleaner is a waste of time.

 

[rythmman]

Re: Nissan 5hp Starting Issues

I just noticed a small crack on the inlet manifold...you wouldn't have a good used one?

 

[TOHATSU GURU]

Re: Nissan 5hp Starting Issues

Nope. We only sell new ones. They run around $20.00 for the part....$25.00 from a Mercury dealer.

 

[rythmman]

Re: Nissan 5hp Starting Issues

Cleaned the carb, Again. Now I still have 2 issues. The motor started, but still stutters from half to full throttle. Then when off for 1 hour, was VERY difficult to start. I removed the sparkplug, which was wet with gas. Replaced it and started up easily. Is this another electrical issue, perhaps a weak coil?

 

[pvanv]

Re: Nissan 5hp Starting Issues

Anything is possible, but weak spark is rare on these. A wet plug may be a result of too much fuel -- possibly from over-choking when cold.

One technique we use for older, well-worn motors when cold starting is to set the choke, pull once, open the choke, and then pull. That seems to deliver enough enrichment to start on some of the older motors without flooding the plug. Even works on my ancient 4-stroke snow blower, which suffers from low compression due to many thousands of hours of use and no tear-downs.