Am I missing anything?

packman35

Petty Officer 2nd Class
Joined
Jul 21, 2008
Messages
113
I have a 93 115 TLET. It ran fine when I got it earlier this year but recently has begun to run like crap. It is hard to start and idles like crap. Really rough idle and will usually stall out unless I give it a little throttle. It seems to run OK at medium to high speed but I feel like I may have lost a little hp - but it's hard to tell. I put in new plugs a few weeks ago. I also changed the fuel filter recently.

I plan to rebuilt/clean the carbs in the coming weeks as I think dirty carbs (don't know when/if they were ever cleaned before I owned the motor) are the likely cause but I wanted to make sure I am not missing anything else that might be the culprit.

I have checked the sparks and get 1/2" on the each cylinder so I don't think is an ignition problem. However, the battery is on its last leg. It is slow to spin the motor up when I start it. Would a low bat voltage cause poor low speed performance?

I checked compression a while ago with the engine warm (not hot) and got 95or so on three cylinders and 90 on the fourth.

Anything else I should look for?
 

psteurer

Petty Officer 1st Class
Joined
Nov 10, 2008
Messages
366
Re: Am I missing anything?

Probably the carburetors as you say. How often do you does the boat sit between uses. Fuel sitting in those old non-alcohol resistant lines is a slow death for your carburetor. A bad battery would not cause the problems you ar having.
 

packman35

Petty Officer 2nd Class
Joined
Jul 21, 2008
Messages
113
Re: Am I missing anything?

The boat gets pretty regular use. No more than a couple weeks between uses at most so far this year.

Thanks for the reply. I'm hoping that cleaning the carbs will do the trick.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: Am I missing anything?

Once the engine is started it does not need the battery for ignition purposes. The engine's stator will fire the plugs with the rotation of the flywheel only. An easy/quick check is to make sure you have spark when the engine is warmed up. Ignition problems tend to show up once the engine heats up to normal operating temps. Take an inductive timing light with you next time you go out. When on plane, check all 4 plugwires for consistent spark. Look for misfires or no fires in the light flashes. Make sure the bottom two plugwires are not shorting out on the cowling latches. Pull and visually check the plugs to see if all four look the same color. If the spark looks solid, then turn your attention to the fuel side.
 

packman35

Petty Officer 2nd Class
Joined
Jul 21, 2008
Messages
113
Re: Am I missing anything?

Thanks emdsapmgr for the advice. Not sure how I'll measure the timing and keep the boat on plane at the same time. That must take some loooong arms! :D Teaching my wife to drive the boat is a project this off season.

As for the plugs, I have noticed that mine are usually wettish and black/oily. Does this tell me anything? I'm not real sure on how to read spark plugs.
 

rockyrude

Lieutenant Junior Grade
Joined
Sep 10, 2007
Messages
1,120
Re: Am I missing anything?

The good news is that black/wet plugs is usually a rich condition, far better than lean which is bad for the motor.
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: Am I missing anything?

You need a pal to go boating with you, to steer the boat. You are not trying to time the engine, but rather check/verify the flashes/pulses from the timing light as it signals the pulses from the power pack. I would expect the plugs to be black and wet after idling-you want them all to look the same.
 
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