Outboard still rough after usual suspects

[GreenWave]

Originally Posted by jim King

Sometimes it can be a simple solution often overlooked:
I had a similar problem with a dingy motor on a chartered boat in the Bahamas,
After working on it for about an hour I discovered that the kill switch gap had narrowed causing it to run rough especially when reved up. I adjusted the kill switch to sit at a wider gap and it ran fine.

How did you make that adjustment?

[Rumrace]

It’s kinda a copy of the Merc. My first thought is fuel starvation. So inner membrane of fuel pump tear.

Second neutral safety switch which cuts out the engine when you shift.

Both are easy repairs and common problems

[Rumrace]

I’m looking at diagrams for the 3.5 and the 15. Identifying the engine would help. If the inner membrane gets a tiny tear the pump still works but won’t keep up with the float bowel demands. In car say Chevy V8 there is weep hole and immediate gas stink. Same engine in a boat the the weep hole is sealed and the search for fuel starvation begins.
I’ve found red crystals in Yamaha and Merc fuel pumps. I think their shape little edges finished off the inner membrane. Suzuki uses a rotating pump they swell and rip on the bottom.
Some time winter oil is not cleaned out properly and solid resin jams in idle passages in carbs and fuel pumps.
Found Yamaha Honda, and Merc fuel pump kits and impeller kits at a local Canadian Tire with a large dedicated boat parts area. Was shocked and price was perfect

[Rumrace]

All Canadian gas is required to have 10% ethanol and many have 15%
If an engine destined for North America is not designed to handle this it has no market.
In the mid 90’s BMW shipped 530 and 540 with new V8’s and a nicklesilver coating of some type. At 100,000 miles if treated perfect the coating was gone and the car a wreck with an 8500 dead motor. BMW had a secret warranty to cover clients but it was a huge set back for them. The previous 535 I6 being famous for a million kilometres. A reputation damaged by ethanol.

[Be Free]

Originally Posted by soopad00pa

Pulled the plug so I can try and get a replacement. It's pretty gunky again after about a minute of running. It's not wet and smells like the shooting range so I'm going with carbon instead of oil.

I'm guess this is my issue. So, uh, what's my issue..?

It looks like classic carbon fouling. Weak spark or too much fuel are the common causes. Since you mention cleaning the jets with a wire I'd suspect that one or more of the jets is too large now. It does not take much to damage them.


Other possibilities to check are float valve leaking, float misadjusted, improperly adjusted air/fuel mixture, and sticking choke.

[rslifkin]

Originally Posted by Rumrace

All Canadian gas is required to have 10% ethanol and many have 15%
If an engine destined for North America is not designed to handle this it has no market.
In the mid 90’s BMW shipped 530 and 540 with new V8’s and a nicklesilver coating of some type. At 100,000 miles if treated perfect the coating was gone and the car a wreck with an 8500 dead motor. BMW had a secret warranty to cover clients but it was a huge set back for them. The previous 535 I6 being famous for a million kilometres. A reputation damaged by ethanol.

Ethanol had nothing to do with the BMW Nikasil coating issues. It was sulfur content in gas. Ones sold in Germany and other places with low sulfur content gas held up fine (and the coating proved quite durable). In the US, sulfur levels hadn't been limited as tightly yet, so the coatings degraded and failed. BMW replaced a lot of engines under warranty with a new version with a different coating.

[soopad00pa]

Hmm. The jets are tiny so the wire I used was a single copper wire from a brush. About hair thick, but obviously stiffer. If that damaged it, then hell, I dunno what to do.

I've also tried actuating the choke manually and that doesn't change anything. The oil looks like new (cuz it's close - there can't be 36hrs on this thing), so I think that the rings are ok.

The float floats fine. The needle does what is supposed to but it is a piece of crap so I'm trying to source a replacement.

I dunno about the fuel pump membrane, but I think I have the opposite problem.

I will check the kill switch and see if I can figure that out.

And Rumrace - it's the 6.5hp 4 stroke Hangkai. I haven't been able to come up with a service manual online, so if you can find a link it'd be very appreciated.

[Rumrace]

https://www.downloadboatmanuals.com/motors/hangkai/

Promise me you’ll never use a wire brush near a carb again. We can still be friends.

Captain Phab Carb and injector cleaner is the best I’ve used. Sounds like with low hours you have crystals in idle jets. The choke should make a huge difference

I doubt it’s the fuel pump after reading
Have you confirmed a good spark ?
Is the spark plug properly seated and not fractured ?
I’m going to read your manual

[sanibel sailor]

In similar situations, I clean the carb again. I am usually reluctant as I just did it and I am sure everything was perfect... my record is three "perfect" tries. On very small engines, the passages are tiny and clearances are tight so they don't tolerate any gunk.

[soopad00pa]

It was just one single wire swishing around in a hole! I promise

By the choke not making a difference, I mean taking the cowl off and manipulating it by hand instead of by wire. The wire mech is cheap and feels funky, but I get the same travel both by wire and by hand. Choke still chokes.

It's a new plug and it fires right up. It did immediately carbonize tho.

Thanks for the link! (Edit - the manuals are in Russian. )

[GreenWave]

If the plug is fouling after one short run then there is a burn problem, plain and simple.

[sanibel sailor]

Just did the itty bitty carb on my Honda 1000i generator. No wire handy so I improvised.
Plucking a toothbrush bristle rather than a copper wire is my new preference.

[soopad00pa]

Sure, but what's the fix?

Choke works. Float is dry and floaty. Needle passes the drop test. All is clean. What am I missing?

[sanibel sailor]

clogged passage on emulsion tube?

[soopad00pa]

I have no idea what that means