96 looper v4 low rpm misfire

[funkyfresh]

I recently bought a non running boat with an evinrude E90eledr 90hp motor. I've got it running well at WOT and idle, but at about 1000-2000 rpm it is rough, shakes, smokes a bit, and sounds like it's down a cylinder. If I jab the throttle to full it takes off with no hesitation and runs great. Also, while it is missing I tried pushing my key in to add fuel but it doesn't clear the problem, only bogs it down. Here's what I've checked
-Cleaned the carbs, new primer bulb, hoses, o rings
-Had a mechanic set the spark advance lever sync
-New plugs, champion Q78 (forgot the whole s/plug number)
-Spark wires test good with an ohm meter
-Stator tests good @ .3ohms resistance, puts out 12.5v at idle, and climbs to 14.4 around 1500 rpm
-Compression is 135-140 across all cylinders

The plugs all look fairly uniform but they are always wet, and black. What else can I check?

 

[boobie]

You may want to do a good sync and link on it.

 

[boobie]

Edit........

 

[Bosunsmate]

how thorough did you clean the carbs?

 

[funkyfresh]

I stripped down each carb and sprayed brake cleaner and compressed air into all of the passages to make sure they were clear. however at the time I didn't have carb kits so I re-assembled with the existing gaskets and needles

 

[pn]

try a decarb session with seafoam

 

[V153]

Sounds like it could be a chunk of crud in the midrange circuit. Did you remove & inspect the jets when you rebuilt?

Generic carb cleaner doesn't cut it. Get some "Power Tune" or equivalent. I use Valv-Tect. Doesn't hurt to soak em in a can of Berrymans, etc too.

Careful with compressed air. I bleve they recommend no more than 25 psi.

Compression #s are good. Doubt it needs a de-carb.

 

[funkyfresh]

After tearing down my carbs for a second time I discovered that I had stuck one of the floats on upside down. Doh. Need to test run the boat but I have a good feeling this will solve my problem