1994 Johnson 48 SPL carb or plug problem?

[takirb]

I took the boat out for the first time 2 days ago and it wouldn't idle for more than 15 secs without fast idle level 1/4-1/2 up. i had a fresh tank of new gas/oil. Thinking it's probably just been sitting for a bit, i ran it at medium throttle up the lake for about 20 min total and it ran fine. At the end of the run, it still wouldn't idle w/o fast idle lever but ran fine under load.

Took it out again today, same idle problem, but ran fine for about 20 min at medium throttle, then started surging, losing power, and left us stranded for about 20 more minutes. I finally got it back running again and every 5-10 min it'd start surging for another 5-10, then run fine but with limited power only. For most of the trip back, i could barely go faster than idle speed or it would induce surging. I'm calling the shop tomorrow to report this as i just purchased this boat and was told it ran fine. Could this possibly just need carb cleaning or new plugs? I fear the shop will run it fine with muffs or low speed in a tank for a few min and never encounter the problem.

 

[tashasdaddy]

Re: 1994 Johnson 48 SPL carb or plug problem?

i would start with a carb cleaning and rebuild.

 

[takirb]

Re: 1994 Johnson 48 SPL carb or plug problem?

The previous surging problem turned out to be leaks in the fuel tanks around the fitting hookups and gauges. I've fixed the surging problem, but haven't been able to make a dent with the idle issue. I've talked with some other boaters and they've had to do the same as me - balance fast idle level until ready to throttle, drop the level and throw in gear real quick. Is this hurting the motor? the mechanic showed me where the screw was on the motor to advance the timing while in water to see if that'd help, and also showed me the mixture screws on the carbs to adjust if the timing screw didn't help. According to the mechanic, it idles just fine when on muffs. According to me, it doesn't idle at all in water (5 secs tops). Would the carbs or timing make it act differently using muffs vs water or does it sound like water getting in somewhere while actually in the water?

 

[tashasdaddy]

Re: 1994 Johnson 48 SPL carb or plug problem?

i told you what you needed, it will idle on muffs and the idle has to be set higher on muffs so it will idle in the water, in the water there is back pressure on the exhaust, that is not there on muffs. but you stalling problem is clogged high speed jets in your carbs. also you idle speed will finally have to be fine tuned in the WATER with the motor IN GEAR.

you go advancing in timing and screwing with things, you then throw the link n sinc off, complicating the problems.

suggest you get and OEM Johnson manual if you are going to tinker.