Nissan 9.8 4-cycle won't idle - gas in oil...

[rdthoms]

New to me 9.8hp Nissan 4-stroke electric start on a 25' sailboat. PO had oils and impelller changed last summer and has not had it out much at all since then. He informed me to let it run dry at end of the day. Gas was probably stale, I added 1.5gal (1/2 tank) fresh. Took it out for the first last week absolutely no problems (easy start, good idle). So happy.

Took it out yesterday and it started easy enough but leaving the marina it died when cut back to idle. Quickly raised the sail and was able to get going, got into the middle of the lake and restarted it without too much problem but I could tell when I backed off the throttle it was not happy. Coming back into the marina it died when slowing to idle, got it restarted a couple of times but eventually the wind was too much so we tied off to a close by dock instead of our regular slip.

Today I went back and found that it really will not idle at all without stalling (after warmed up and releasing the choke). I had poked around on iboats last night and saw that besides fuel and carb, excess oil or potentially gas in oil might be a problem so I checked the dipstick and it is very full and I'm pretty sure there is significant gas in the crankcase oil. Does that mean a leaking fuel pump?

What would be the suggested course of action? Before I found the gas in the oil I was sure it was dirty fuel or dirty carb. Now I'm not so sure. I am throwing out the old fuel and willing to have a shop do the carb and fuel pump, does that sound like the best thing to do? Should I first try to change the oil to see if a) it fixes the problem, and b) does the gas return? To be honest I'm not wanting to take risks as I quickly found out how important a working motor is when trying to dock a sailboat in some wind!

Thanks!

 

[Sea Rider]

The engine is making oil, the oil level has risen high, not necessarily due to fuel on oil, but due to environmental issues. Get rid of all oil in crankcase, just fill to middle level, that's between min and max marks on dipstick. Use mineral W 10-30 oil. Paul knows about engine making oil...

Happy Boating

 

[pvanv]

New to me 9.8hp Nissan 4-stroke electric start on a 25' sailboat. PO had oils and impelller changed last summer and has not had it out much at all since then. He informed me to let it run dry at end of the day. Gas was probably stale, I added 1.5gal (1/2 tank) fresh. Took it out for the first last week absolutely no problems (easy start, good idle). So happy.

Took it out yesterday and it started easy enough but leaving the marina it died when cut back to idle. Quickly raised the sail and was able to get going, got into the middle of the lake and restarted it without too much problem but I could tell when I backed off the throttle it was not happy. Coming back into the marina it died when slowing to idle, got it restarted a couple of times but eventually the wind was too much so we tied off to a close by dock instead of our regular slip.

Today I went back and found that it really will not idle at all without stalling (after warmed up and releasing the choke). I had poked around on iboats last night and saw that besides fuel and carb, excess oil or potentially gas in oil might be a problem so I checked the dipstick and it is very full and I'm pretty sure there is significant gas in the crankcase oil. Does that mean a leaking fuel pump?

What would be the suggested course of action? Before I found the gas in the oil I was sure it was dirty fuel or dirty carb. Now I'm not so sure. I am throwing out the old fuel and willing to have a shop do the carb and fuel pump, does that sound like the best thing to do? Should I first try to change the oil to see if a) it fixes the problem, and b) does the gas return? To be honest I'm not wanting to take risks as I quickly found out how important a working motor is when trying to dock a sailboat in some wind!

Thanks!

If "very full" means way over the full mark, and the oil reeks of gas, you could have a blown diaphragm in the fuel pump. Drain the crankcase (5/8 box or socket), refill to 1/2 way on dipstick -- only about 3/4 quart. Use non-synthetic NMMA-certified FC-W oil, SAE 10w-30. Be patient -- easy to overfill. Check plug condition. When priming gas, the bulb should get firm. If it won't, you could have a bad pump, leaking gas into the crankcase. If the oil level rises significantly when running, likely a bad pump.

OTOH, it might just have been overfilled with oil.

 

[rdthoms]

Thanks. I'll drain/refill oil this weekend and check (probably just change) the spark plugs. Also new fresh gas. I'll report back results. Is there a favorite tool for draining the oil from the dipstick tube? Or is it easy enough to do with the drain plug (without removing the motor from the boat/water)?

 

[Sea Rider]

You'll need a vacuum oil remover machine to do it through the dipstick. Use the oil plug, don't let oil plug plunge into the blue. If task is umconfy, remove engie from boat and change oil and filter at terra firme.

Happy Boating

 

[rdthoms]

I was able to drain the oil through the dipstick with a large syringe/tube. Pulled out over 900ml and put back in about 750ml (to half way mark on dipstick). Also drained the fuel tank/hose and replace with fresh non-ethanol. Unfortunately that had no effect on the idle problem. The motor would run with the choke pulled out but a little rough (vibrated alot), push the choke half way in and it would run really nice. Push the choke all the way in and it would die. Today I'll try new plugs and if that does not help, I'll pull the carb and take it home for a good tear-down/cleaning (dip).

 

[rdthoms]

OK so spark plugs did not help. Tore down the carb and soaked it for hours in Gunk dip. Actually soaked the idle jet overnight. Before I could not see light through the idle jet, afterward I could, so I was sure this was the problem. Got everything back together and installed on the motor and still the same problem. Starts on first pull and will idle with choke on but when choke is off it will die. Also will run with choke off but some throttle. I tried to turn up the idle stop maybe half turn but that just caused a too fast idle. I was about to give up and take it to a shop but a dock mate came by to take a look. He started messing with the linkages on the carb and could get it to hold an idle well. It seems there was somtheing wonky with the throttle linkage that runs from the carb to the tiller throttle mechanism. This particular linkage has a slot on the tiller side that allow some "slop" there, I think to allow the choke linkage can open the throttle a little bit. Anyway after a few adjustments on the carb end of the throttle linkage (adjusting the brass slider that the linkage runs through) everything started working fine! Took it out two days in a row with no problems!