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2011, Honda 50 EFI problem

C

Crab _man

New member
Hi All :) ,
I have a pair of Honda 50 EFI's on my commercial fishing boat, I do all servicing and maintenance myself and normally manage to solve most problems.
However...I currently have a niggling fault with one engine which I can't seem to cure..when starting the engines in the morning when cold, normally just turn key, wait for the fuel injection beeps then turn to start, they idle fast then warm up and slow down to a normal idle speed, recently one engine starts fine when cold but doesn't rev itself to warm up, it just idles slowly and sometimes stops unless I give it a bit of revs to heat it up, even then it idles slowly and seems to shake a bit after its warmed up.
I turn the engines off and on all day while working fishing gear and this engine when warm now doesn't start unless I lift the idle lever and give it a bit of revs before I turn the key, if I don't do this it won't start at all but starts first time if I give it a bit of revs.
I also think it's smoking slightly and has used a little oil recently, not much but it's never used any before ( this might just be coincidence and not related).

So far I have - fitted new spark plugs ( and also swapped them with other engine to double check) .
- swapped the 02 sensors as I had a problem with one which I replaced a couple of years ago.
- changed the thermostat and flushed out cooling system ( it is pumping plenty water).

It is running fine and in daily use but it's just a niggling fault that I'd like to get to the bottom of, I'm now thinking auto choke problem perhaps? Not sure where to look for this, any help or advice would be much appreciated! Thanks in advance :)
 
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There is not an auto choke on that 50. But there is a Idle Air Control valve.

That is the first place that I would look. See part #10 on top of the intake manifold. http://www.boats.net/parts/search/H...50DK2 LRTA/INLET MANIFOLD INJECTOR/parts.html

Remove it and make sure that the holes into the manifold are clear. Also, make sure the screen on the IAC is free of carbon....and make sure that the connector pins are clean and making good connection. They probably are since you did not say anything about an alarm and check engine light.

It is also possible that it's internal parts are frozen. The easiest way to check for a bad IAC, in your case, is to take the one off of the other engine and try it on the problem engine.

The IAC controls the amount of extra air let into the intake manifold needed at startup and to keep the idling smooth. At startup, it lets extra air in and slowly decreases the amount of air as the engine warms up.

So give that a try and see if there is any change.

Mike
 
Hi Mike,
Many thanks for your excellent info!
You were right! It was a 5 minute fix! I took off the IAC tonight and the mesh part was covered in carbon and the other hole was partially blocked too, a quick scrape and clean and the engine is running perfect, I checked the other engine and cleaned the one off it also but it wasn't as bad.
I would never have thought to check that, your help is much appreciated!
If your ever in Scotland there is a couple of lobsters with your name on them :D :cool:

many thanks!
 
My wife and I will be there this weekend....counting on those lobsters. LOL

It is always nice when there is an easy fix.

Be safe out there.

Mike
 
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