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Idle problem

Regardles of the carb age, it sounds like you are lean when accelerating. See if it squirts raw fuel into the airstream when opening the throttle. If not, the accelerator pump is not doing its thing. You can only do this once or twice before the accelerator pump reservoir is dry... then when running, it should refill.
 
Got it. I'm not sure how to do that. Do I remove the carburetor but leave it attached to the fuel line? Or if I am supposed to leave it attached how do I observe whether the raw fuel is squirting into the airstream?
 
Inshore22 said:
Got it. I'm not sure how to do that. Do I remove the carburetor but leave it attached to the fuel line? Or if I am supposed to leave it attached how do I observe whether the raw fuel is squirting into the airstream?
Click to expand...
Take off the air box and look down the throat. Then cycle the throttle.
 
Checked the accelerator pump and it was delivering a fuel spray. I replaced a fuel pipe and unscrewed and rescrewed in the water separating filter.

Took it back out and it seemed better actually but still delayed accelerating. Then after being out for a while couldn't get it to electric start. When I pressed the button I'd just get a click. Started immediately with the pull cord.

Wondered whether I was overheating so I checked the impeller and one of the arms was ripped off (https://drive.google.com/open?id=1jBMgWUjzHRGCXnG5Z6UUiIV3ISsJy2bO). A new one is coming tomorrow. Could this conceivably be related to the accelerating issue?

Also, I can't find the arm that ripped off the impeller. I looked down in the lower unit and its not there, not at the thermostat, and I sprayed the hose in the thermostat opening and flushed really well and nothing came out. Also did weed whacker coil in the tell tale. Is there a particular place I should be looking?
 
The old impeller could have been dry rotted with time. The missing vane probably pumped out through the motor with the cooling water. If wondering about temperatures, get a cheap IR thermometer at the hardware store. Crankcase and head should be around 150F. Running too hot might make it seem a little rich. Yoursymptoms are of being too lean. Are both base gaskets there and OK, separated by the plastic thermal spacer?

Check whether your starter motor or the solenoid are causing the electric start to fail.
 
The base gaskets are okay, I think. I replaced them both recently.

One thing about the motor not starting on the lake is that after I got it home and tried it in the driveway it started right up with electric start. Does that indicate anything as to whether it might be the starter motor or solenoid?
 
When I'm measuring temp with the IR thermometer should I be checking on the cylinder head cover next to where you put the oil? (#8 on this diagram https://www.boats.net/catalog/nissan/2007/nsf18b2-4-stroke-nissan/cylinder-head)?

On the cylinder head cover I got up to about 158 but when I checked on the side of the cylinder head it got up to about 165. This is idling in the driveway.

Also, what ballpark RPM should I be idling at in neutral in my driveway?
 
The book says 950-1000 in N, 900 in gear. I usually for a little higher. Your temp is a hair high, but OK.
 
I found the impeller fin right above number 12 on this diagram: https://www.boats.net/catalog/nissan/2007/nsf18b2-4-stroke-nissan/drive-shaft-housing

I think it was prob up higher in the motor and it backflushed down when I took out the thermostat and sprayed the hose in there.

Now the engine is running about 15 degrees cooler.

So my new working theory is that there was nothing wrong with the carburetor and I've been overheating off and on as that little fin worked its way through the cooling system and found itself restricting flow more at times and less at other times.

Checked the oil and it is showing as over the top end of the fill range whereas it was about 3/4 of the way up when I last checked it. So maybe water got in?

My plan is to change the oil and then do a compression test and see if I am in range. I will be looking for water in the oil when I drain it.

Is there anything else I should look for or any gaskets or anything that would definitely need to be replaced if there is a little water in there?
 
Yeah; sounds like that broken-off vane was causing intermittent slight overheating. If you had water in the oil, it would look like a milkshake. If under 50 hours since the last chasnge, just lower the oil level back to 1/2 or 3/4 on the stick. Seldom ever a gasket leak causing oil gain. If so, likely the base gasket under the motor. I have one in stock.
 
So I got the impeller vane out, put in new water pump, oil change and filter, and gear oil. Took it out today and it was running great. After I ran at or around WOT for about 10-15 minutes I took off the cover and my IR thermometer got about 170 degrees on the cylinder head near the oil filler cap on the back of the motor.

In a previous reply you had said it should be about 150 degrees (and it is 150 after idling for 20 min in my driveway). Is 170 reasonable after running WOT 10-15 minutes?
 
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