Sick Outboard Diagnosis ... Help!

[Melchester]

I have just spent the morning taking apart he carburettor of my Aqualine 8hp two-stroke outboard. Such fun. Seemed fine just a few grains of salt or sand in there. The spark plug sparks and is wet. But it won't start at all. The problem first began when I ran into a sandbank (in my 24ft fixed keel yacht). I had to rev the outboard in reverse. Got off the sandbank - motored for a few yards more then the engine stopped. I would restart but every time I tried to increase the throttle it died. So I thought I had sucked something nasty into the carb - but that does not appear to be the case. Now it simply shows no sign of starting at all.
Any idea what might be the problem? Was the sandbank just a coincidence? Yes I know Aqualine is a chinese knock-off of a Tohatsu or something - and I deserve all the trouble I am getting.

[JPA Cate]

Hi, Melchester,

I'm not an expert at all, but part of what happened was that you sucked up sand into the cooling spaces. Maybe that is part of the problem. A really good high pressure flush out may help, especially if you can get it running.

Something that might have happened is a coincidental failure of the CD unit, if that motor has one. It can be hard to track down if something else has gone wrong as well.

When you tested the plug, did it emit a spark? If it did not, look at the CD unit.

Ann

[belizesailor]

The sand bank is likely coincidental. I suspect the higher revs sucked gunk into the carb from fuel tank (there is no normal path from sand bank to carb). The stress of higher revs may have damaged something.

How did you clean the carb? Unless you tear it down and clean it thuroughly its not likely clean. Remove it, tear it down, clean it again (careful w jets use something soft like a piece of copper wire)...sometimes it takes a couple of tries.

Plugs. You say a plug is wet. That usually indicates flooding of fuel from carb. When cleaning carb check that float valve is not sticking. Clean/replace plug and check that its got spark.

Fuel flow. Check for unobstructed flow by disconnecting fuel line at carb and squeezing priming bulb.

Fuel pump. Higher revs could have stressed and damaged the fuel pump diaphram. Tear down fuel pump and check diaphram for damage...even a tiny hole will affect operation.

Fuel filter. Do you have an external filter? Most engines have an internal filter. Check both to confirm not clogged.

Fuel. Is it new & clean? Is there visible gunk in the tank?

[Melchester]

Thanks Ann. Yes the spark plug seemed to be sparking (although it was a very bright day, so not 100% certain). Not sure what a CD unit is or does :-(

[Melchester]

Thanks BelizeSailor. I did take the carb apart completely and poke it's little holes with a fine wire. Fuel flow seems fine - it has a internal and external fuel supply and I tried both. The float valve definitely moved but didn't seem to have a huge range - wasn't sure quite how much movement it required, but it all seemed in good condition.
The fuel is not new, but had been working fine for 45 mins before I hit the bank. I checked all the filters - clean as. The fuel pump diaphragms looked whole. There were some small crystals - (salt or sand) on one side of them - but I cleaned that off.

[GordMay]

Greetings and welcome aboard the CF, Melchester.

[lancelot9898]

I remember spending all morning years ago trying to get my 5 hp Nissan to start. I checked the spark and the inline filters and was getting ready to take the carb apart when I suddenly realized that the emergency kill switch was somehow become engaged and that was the cause of the problem. Does your motor have a kill switch that you attach to yourself for shutting down the motor should you fall overboard? Also how long have you been using the motor without any problems since I'm considering getting a motor from China, but worry about the quality.

[belizesailor]

Originally Posted by Melchester

Thanks BelizeSailor. I did take the carb apart completely and poke it's little holes with a fine wire. Fuel flow seems fine - it has a internal and external fuel supply and I tried both. The float valve definitely moved but didn't seem to have a huge range - wasn't sure quite how much movement it required, but it all seemed in good condition.
The fuel is not new, but had been working fine for 45 mins before I hit the bank. I checked all the filters - clean as. The fuel pump diaphragms looked whole. There were some small crystals - (salt or sand) on one side of them - but I cleaned that off.

The float valve doesnt move much (cant before it hits it stops).

Check spark with a new plug or tester...or just get a friend to hold it. [emoji6] If no spark then likely electrical.

If so and its not something simple like a bad connection/kill switch then replace the ignition pack (most are potted in epoxy so not practical to repair).

[Lake-Effect]

(I would have expected to find zero grains of anything in the carb, so that concerns me a little...)

Guessing it's either fuel issue (80% chance) or electrical (20%)

How old is the gas, anyway? I am a believer in the mystical healing powers of NEW ethanol-free gas. I also like a shot of SeaFoam (gas treatment) in the tank now and again.

Can you confirm that gas is getting to the cylinder? (eg wet sparkplug, you can smell gas in the cylinder(s))? Did you try squeezing the fuel primer bulb while trying to start?


Is the motor easier or harder to pull over with the starter, or the same as before it quit?


I have a couple of Chinese engines (inverter-generator, water pump). They're not Hondas, but they still obey the same laws of physics. But to lancelot - personally I would rather get a used outboard of reputable make than roll the dice on a new Chinese one, til we get more feedback from users on their reliability.

[Bill O]

https://www.parsunparts.com/As a start usually two things to look for in in OB troubleshooting, fuel or spark.
Obviously sand in the carb isn't good, but an easy fix. Clean fuel tank and add or change in-line filter before fuel pump and carb.

A wet plug usually means weak or no spark, but getting fuel. Is it the correct plug & heat range? gap correct? As suggested, try a new plug (manufact. spec or another brand alternate) w/ correct gap. Before installing, put new plug in spark plug end and hold electrode to engine block to see if you have a good spark (blue/white is strong, while a red/yellow spark is weak and may not be enough).
If no spark, ck kill switch.

If the spark plug change doesn't do it, may need to change points, condenser and set timing.

Didn't find any parts diagrams for Aqualine OBs but did find this link that said they had parts to fit a long list of Chinese OBs

Bill O.

[belizesailor]

Originally Posted by Bill O

As a start usually two things to look for in in OB troubleshooting, fuel or spark.
Obviously sand in the carb isn't good, but an easy fix. Clean fuel tank and add or change in-line filter before fuel pump and carb.

A wet plug usually means weak or no spark, but getting fuel. Is it the correct plug & heat range? gap correct? As suggested, try a new plug (manufact. spec or another brand alternate) w/ correct gap. Before installing, put new plug in spark plug end and hold electrode to engine block to see if you have a good spark (blue/white is strong, while a red/yellow spark is weak and may not be enough).
If no spark, ck kill switch.

If the spark plug change doesn't do it, may need to change points, condenser and set timing.


Bill O.

Good advice, but points & condensor? Its been a long time since Ive seen those. What year model is this engine?

[Bill O]

Originally Posted by belizesailor

Good advice, but points & condensor? Its been a long time since Ive seen those. What year model is this engine?

OK you got me there, being a little too old school!! Most likely is a power pak of some sort, but then again some older OBs may still have points and not all are electronic. Wasn't that long ago I worked on an older Evinrude that still had points

Was always cheaper to check/swap out points than a non-returnable power pak.


Bill O.

[CAPAZ]

just went through this on my 8 hp Yamaha, pulled and cleaned carb....no good
rebuilt carb....no good. went to Boat.net bought new carb for around 100$. so far 2 seasons of running like a top. just fyi

[DenverSailors]

Maybe a silly Q, but did you check the fuel line from the tank to the motor?

[Bill O]

Originally Posted by CAPAZ

just went through this on my 8 hp Yamaha, pulled and cleaned carb....no good
rebuilt carb....no good. went to Boat.net bought new carb for around 100$. so far 2 seasons of running like a top. just fyi

Thinking you have a 4 stroke? For those, buying a new carb is the way to go if you can't sonicate the carb bodies to get the crude out of the small ports.


Another trick (for the OP) to try to determine if its a electrical or fuel problem is a small shot of starter fluid into the carb. Open the choke plate before squirting in starter fluid, close choke then give it a few tries to start it. If a no go then you isolated it to no spark.
(note don't run a 2 stroke on straight starter fluid/ether too long. It needs the oil normally mixed in the fuel for lubrication)