94 120 Looper running better - decarb was the trick

[mankato]

Thanks to lots of help here and many, many hours of searching old posts, my 94 120 looper is almost where I want it to be. Here's where I am:

Replaced power pack due to no spark on one cylinder, good strong spark all around now, new Champion QL16V plugs, replaced fuel filter/water separator, new main fuel line, primer bulb (used a temp 6 gal tank to ensure no fuel issues or air leaks below deck), new primer solenoid gasket/cover (was leaking). Started, but not without babying the choke/idle well and accellerated okay, but topped out at 4600 rpm's and wanted to die during decelleration. Performed link & sync, no apparent improvement. Decarbed by the instructions found here... That was it! Starts quick, runs smooth and strong now from just above idle to 5600+ rpms.

Now to finish it off;
Got a sneeze at idle that sometimes shuts the motor down. Just want to make sure I understand what I'm looking for. I looking for an air leak at idle by feeling for a puff of air in the area of each carb (when the sneeze occurs), correct? And an air leak causes a lean condition on the cylinder "across" from the carb, not on the same side of the engine, correct?

What should WOT on a 94 120 be? My manual just says 5000-6000? I was getting 5600 and it felt like it had a little more rpm's in it but I was running light weight (just me, three batteries, a full bait tank and only 20 gals fuel) and I didn't want to exceed WOT specs. Boat is a 19' center console with 60 gals fuel at full and sometimes 4 adults on board. I'm running 151/2X15 aluminum prop on a commercial (larger gearcase) lower unit with 1.85/1 ratio. Thanks again !!!

 

[OBJ]

Re: 94 120 Looper running better - decarb was the trick

Glad to hear your progressing with the engine....8)

Each carb has a low speed needle that can be adjusted in or out. Most likely the low idle sneeze is because one or more of the needles are not adjust correctly. Your manual should have a procedure for the correct adjustment. You can also go to the FAQ section here on the forum and check out the post by Joe Reeves on setting needles. It'll help. Here's the link.

http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=36;gtid=1105882

The 5600rpm at WOT throttle sounds about right with a normal load. If you have a timing light with a tach function, you can cross chech the rpms to be sure the tachometer is correct.

 

[Brew2]

Re: 94 120 Looper running better - decarb was the trick

I could be mistaken but.....don't these loopers have three (high, med, low) fixed jets? (ie. no way to adjust them short of swapping them out for a different size)

Maybe I'm thinking of older models.