Honda 30hp won't accelerate past 1/4 throttle.

[v8George]

Hi all, I have a 2006 3 cylinder Honda 4 stroke outboard that went from running great to running terrible. I had some issues with it dropping a carb here and there so I cleaned them and got it running on all 3 cylinders. It ran fine, then after sitting for a week, it refused to go over 1/4 throttle, it just bogs. I pulled the thermostat and it was pretty nasty so I cleaned that out and replaced the t-stat with a new one. It idles OK, not great, and acellerates to 1/4 throttle hard, then dies. The fuel tank is vented, the plugs are good. The oil is clean and the water pump is moving water fine. I also added fresh fule and a little seafoam.
I am going to try replacing the filter and fuel pump diaphragm but wanted to see if there was some common issue with this motor that I am missing.

 

[ahicks]

Nothing common. Just stuff that might prevent it form getting as much fuel as it needs to get over 1/4 throttle.

Pump would be unusual in my experience. Sucking air at connections (look for fuel leaking), plugged filters (see if you can blow through it), collapsed fuel lines, etc. more common.

You could try hitting the choke when it falls on it's face to see if that helps for a second. If so, fuel starvation is almost certainly the issue.

 

[schematic]

those carbs are tough to clean. reclean them again. be very thorough with the idle jet/pickup tubes (must be internally spotless)
seafoam is for rubbing on your sore elbows.....LOL

 

[v8George]

Checked the fuel lines, no kinking or collapsing. Replaced the filter, it wasnt terrible. All the carbs were tight. I took it out and when it started to die, I choked it which just made it worse. The fuel line bulb was soft and wouldn't pressurize. I took it off and it finally pumped up, put it back on, no difference. It pulls fine up to half throttle and then just dies, I came back to idle and the #2 carb stopped working correctly, I pulled the #2 plug wire with the engine running and there were no changes in idle. I drained the bowl, full of fuel. All I can think is the carb is clogged up somewhere. Does any one have a part number for the rebuild kits for these? I can only find each individual part through Honda.

 

[ahicks]

Dealerships often replace the idle jet tube, but individuals can clean them with a little patience. If you're is idling OK, there's nothing wrong with that anyway. Other than that, if I don't tear any gaskets, I can usually get away with a pretty thorough clean without using parts.

Make sure you check the fuel lines from the pump to the carb while you are at it.

 

[v8George]

I am going to disassemble them and drop them in the ultrasonic cleaner. in the past I have used monofilament fishing line in various thickness to clean the orifices. Hopefully I can get awy with a good cleaning.

 

[ahicks]

For the unfamiliar, finding the orifices can be as big an issue as cleaning them! You aren't going to find monofilament small enough I don't think,, for some of these.

The 75 cent small stainless steel parts cleaning brushes from Harbor Freight are what I use. I pull 1 strand from them and clamp it in a small needle nose vice grip so I don't loose it, and use that to clean them with - carefully!

All are to be confirmed clean by your ability to see through them prior to reassembly. And there are no guarantees. It's not that unusual to have to go back through them a second or third time....

That's what makes them so expensive to have done at a dealership.

 

[Sea Rider]

If everything fuel & carb related is 100% spotless and engine keeps bogging down on a second water run, it's an electrical failure for sure. If having 3 individual small ignition coils crank engine at neutral, check their individual spark outputs with a spark tester, or ground each plug and check if doing their homework right, probably one is faulty and engine is running on just 2 cylinders.

If the test confirms all plugs are producing a spark by any of both methods, it's no guarantee that each ignition coil is spotless, could be heating, shorting itself and missing when running at load at higher rpm. Same scenario applies to the CD unit. Both are the worse case scenarios to troubleshoot right unless you happen to have spare electrical parts to swap and test back on a wot run to find the precise culprit.

Most times electrical related issues are bypassed and fuel pumps, carbs are fully singled out as being guilty.

Happy Boating

 

[v8George]

Follow up. I disassembled all 3 carbs and let them soak in an ultrasonic jewelery cleaner. I made a diluted mixture of Simple Green and water, followed by thorough blowout with an air gun and a 60 gallon compressor. Runs good . https://youtu.be/tepYYic_0yo

 

[ahicks]

Thanks for the update!
I have done dozens of these and very similar carbs, and even after learning early on you need to be very careful, I STILL have to do them over again on occasion.......

 

[Sea Rider]

If Honda engines are prone to develop carb issues should run fuel bowl dry till engine dies of fuel starvation after its use, will keep carbs much cleaner, ideal for engines that are used occasionally.

Happy Boating

 

[ahicks]

Unfortunately there are 3 carbs in play here, and if just one runs dry the engine will likely quit, leaving fuel in the other 2 carbs. There's that issue, as well as the fact the engine will not pick up ALL of the fuel in the carb prior to quitting. Point being, the Honda's are equipped with carb drains that will drain the carb completely. If the engine is going to be sitting for a while, and you don't have fuel conditioner in it, you're WAY further ahead draining the carbs. At that point you're good to go until the gaskets start drying up or something. A long time anyway...

 

[Sea Rider]

If all 3 carbs have their bowls full of fuel why would one run dry and the others remain with fuel ? What need to is : with engine running disconnect the fuel hose at motor side, if combo will be taken out of water gear it forward and at fast idle speed let the engine begin to die of fuel starvation. When that starts to happen pull choke in/out several times till engine finally dies out.

This method is much faster than having to remove each carb bowl bolt frequently...

Happy Boating

 

[ahicks]

No need to remove the float bowl to drain the carbs. The float bowls are equipped with very easily accessed drain screws that will drain every drop of fuel every time. There's no guessing here, that's why I mentioned them in my previous note.

 

[Sea Rider]

It's of no importance whatsoever but nobody said to remove the float bowl to drain the carbs. I said : than having to remove each carb bowl BOLT frequently which is a different scenario.

Anyway milking the carb's fuel leftovers throughout the screws will be only good if going Off Season, too much hassle doing it all the times that will be out boating. Carbs should not be fingered too much nor too often as are extremely delicate and costly elements..

Happy Boating

 

[ahicks]

Different opinions. Not worth discussing further....

 

[Sea Rider]

Different opinions. Not worth discussing further....

Touche!! It's entirely on the OP whichever of both provided options he wants to go for...

Happy Boating