Rough to start, barely idles, runs great above 2000 RPM's

[Halibut214]

2014 Mercruiser 4.3 TKI with 47 hours since new. After storage for several months I now have to pump the throttle to get this started and have to keep it above 2000 rpm's to keep it running. Once I get it warmed up it will idle (roughly) for sometimes a minute or two and die. Above 2000 rpm's however it runs like a top. I do have to pump the throttle to get up on step but once there, no problem whatsoever. I changed out the gas water separator, used carburetor cleaner on it, and ran about 5 gallons of 92 octane gas with carb cleaner through at at high RPM's. So far nothing. Before I start throwing money at it, ideas? Maybe idle air control valve?

 

[alldodge]

Sounds like carb needs rebuilding. The idle circuit is clogged.

 

[Lou C]

Agreed you are forcing it to use the off idle and main system to keep it running so your idle jets/air bleeds are likely clogged.

 

[Halibut214]

So you think the Idle Air Control valve is out of the picture?

 

[alldodge]

Being a TKS carb, your motor doesn't have a IAC

 

[Lou C]

That is simply an old Rochester 2GV with an electrical cold start enrichment system instead of a traditional automatic choke. They are simple to rebuild, much simpler than the 4 bbl carbs.

 

[QBhoy]

It will be the tks enrichment issue. Very common.

 

[Halibut214]

It will be the tks enrichment issue. Very common.

Oh... the ol tks enrichment issue. Well now that tells me a lot!

 

[achris]

Oh... the ol tks enrichment issue. Well now that tells me a lot!

Check the TKS fuse and diode. Likely one or both are shot. If it's the fuse, before you put another in and blow that too, find out why it blew. If it's the diode, just buy one from your local electronics shop (and not pay the outrageous price Merc ask for a simple half dollar diode!). Any 3A (or more) diode will do. Something like a 1N5404 or a 6A4, 6A10...

Chris....

 

[alldodge]

Don't see how its an enrichment issue, post one

Once I get it warmed up it will idle (roughly) for sometimes a minute or two and die.

It doesn't idle under 2000 from cold to warmed up

 

[Lou C]

If you have to push it to 2000 rpm it get it to keep running the idle system isn’t doing much it’s the off idle and perhaps main system that’s supplying the air fuel mix. It’s it possible the auto-enrichment system is not turning off after starting and flooding the engine? I’ve never seen or used one of these personally but it seems as if it’s Merc’s way of making the engine start easily for owners not familiar with auto chokes.
Ok found the description on how this works. As long as you can verify that the hissing stops (TKS off) you most likely can rule out the TKS as a cause and have the carb cleaned & rebuilt. What does the fuel in your water separating fuel filter look like?