2004 90 Johnson carbs rich ,PLSRR

[hevysrf]

New to me engine, compression near 100 on all 4, plugs were light brown.

Carbs were leaking from bowls, black gaskets. Removed carbs, cleaned, then installed new bowls, new brown gaskets.

I removed the high-speed orifices from old and installed in new.

I didn't use the white gasket under the float valve, set float levels.

Now the engine seems over-rich at idle, won't stay running unless I crack the butterflies open a bit. Plugs clean and wet.

I tried mixture screws at every setting from 9 turns to 3 turns with no cure.

Starts easy, planes quick, hit 4800 rpm within seconds.

What could I have done wrong in the rebuild?

[hevysrf]

I'm thinking the floats are ok because the primer bulb gets solid after a few pumps.

I never did a sea trial on this boat, not sure about the previous mechanic competency, as the prop did not have a thrust washer and the clear sleeve was not the carb linkage roller.

[hevysrf]

I may be making some progress, I disconnected the oil feed and ran premix from a portable tank, 100% improvement. I guess it was oil rich, not fuel rich, could explain why mixture adjustment didn't affect idle.

My question now: is there a vro mechanical failure that allows over oiling, or is it safe to say that a fuel restriction or air infiltration is the cause?

[ChampioNman]

Quite often the O ring on the back of the carb body gets pinched on installation of the carbs. If you were to have an Oil side failure it would over oil. You should have gotten a No Oil LED on your system check gauge or tach.

[ChampioNman]

Check this adjustment. http://www.bbcboards.net/showthread.php?t=11790

[hevysrf]

Thanks, linkage doesn't look bad, but I still can't get it to idle. Fine on Quick Start, then it just seems to slow to a stop. Even if throttle opened. Bowls are full of fuel when this happens. Restarts easily.

[ChampioNman]

Have you checked the timing using the ignition analyzer?

[hevysrf]

Not yet, I will have one by the weekend.

[hevysrf]

When I removed reed assemblies, I noticed a leak where the front half attaches to the block.

While turning the crank with a socket you can see bubbles right where the new red sealant stops.

I believe the powerhead will need to come off for this repair?

[ChampioNman]

Is this on the STBD side?

[hevysrf]

Port, starts just under #2.

Pulling #4 plug wire or stopping airflow to # 4 carb didn't affect idle.

I guess that red sealant means some was in there already.

[ChampioNman]

A new intake gasket will probably seal that. How does the plug look on #4? You may have a diaphragm leak on the fuel pump. Take the hose off of the pump that goes to the pulse limiter and check for fuel/oil mix in the hose. Then cap it off the hose and run the motor while squeezing the bulb and check plug again. The pulse on your motor is driven off the #4 cylinder so you may be dumping fuel into the bottom side of the carb.

[hevysrf]

Its not the intake, but the crankcase to cylinder block joint, that's leaking.

[ChampioNman]

That's not a good thing. Try torquing down the Crank case bolts and see if that helps. The red is gel seal that seals the block up on re-assembly.