evinrude 175 (1986-ish) - Rough at idle and low speed; runs good at high speed

[azhunter]

Hey Y'All,

Saturday the boat wouldn't run. I found there was water in the tanks I guess from when I was pressure washing the boat - lesson learned. I completely drained the tanks then added new fuel.

Sunday the boat ran great for most of the morning until it started running rough at idle and at low speeds. It still runs good at higher speeds 3200 + RPM range.

I didn't have my standard oil (Evinrude/Jophnson synthetic) so I bought some Valvoline 2 stroke oil which is a non synthetic. Could this have any affect on the way my boat is running? I doubt it but??????

Any ideas on where to start?

Thanks.

 

[dajohnson53]

Re: evinrude 175 (1986-ish) - Rough at idle and low speed; runs good at high speed

What kind of tanks do you have - built in or portable? The motor ran fine for a while after the drain/replace fuel process, then later started acting up? Any other symptoms? Did you drain and/or replace your water separating and inline filters? Did you drain the carb bowls? Those things can sometimes help if you're trying to get back after a water problem.

In my opinion and experience, if the oil you're using is TCWIII rated, it wouldn't affect your engine's performance in any perceptable way, except some say the synthetics smoke a bit less, so you might see a bit more smoke with the non-synthetic oil.

 

[azhunter]

Re: evinrude 175 (1986-ish) - Rough at idle and low speed; runs good at high speed

The tanks are built in. I drained them the best I could with a siphon hose an then used the ball pump to finish them off. I suppose it's possible that a little water remained in the tanks but I would expect periodic stumbles in the motor rather than a constant miss. I didn't drain the bowls but that's a good idea.

The puzzling thing is that it ran good for several hours before it starting acting up which makes me think that the water from Saturday is not the cause of my problems on Sunday.

I did replace the inline filter. I don't have a water seperating filter but I am going to get one and install it before the next run.

Any other thoughts?


p.s. I did notice considerably more smoke with the non-synthetic oil.

 

[azhunter]

Re: evinrude 175 (1986-ish) - Rough at idle and low speed; runs good at high speed

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[azhunter]

Re: evinrude 175 (1986-ish) - Rough at idle and low speed; runs good at high speed

Can anyone chime in here? Any help would be deeply appreciated. Thanks!!

 

[emdsapmgr]

Re: evinrude 175 (1986-ish) - Rough at idle and low speed; runs good at high speed

Even though you have an inline filter, it is possible you have a small amount of debris in one of the jets... I'd pull the carbs apart, including pulling all the jets. Blow out the carb passages with carb cleaner, esp the idle circuits. Check each of the jets visually, then reassemble.

 

[azhunter]

Re: evinrude 175 (1986-ish) - Rough at idle and low speed; runs good at high speed

emdsapmgr,

Thank you for your suggestion. This is my first outboard motor so I'm a little reluctant to dive in to the unknown without some sound advice first. From the research I have done going through old threads on the same subject, it appears that this is the best place to start.

Is it possible that a weak power pack could cause the same symptoms?

Thanks again.

 

[emdsapmgr]

Re: evinrude 175 (1986-ish) - Rough at idle and low speed; runs good at high speed

Ignition problems can flare up at any time. Age and heat cause electrical components to fail over time. You can check the spark on each cylinder with a simple timing light. Once started, put the timing light on each plug wire. You should see a strong, constant flash from each wire. A bad pack will show up with one or more plugs not firing. Look for weak spark or intermittent spark as a problem.

 

[azhunter]

Re: evinrude 175 (1986-ish) - Rough at idle and low speed; runs good at high speed

Thanks for the tips. I'll try this first and see what I can figure out. It sounds much less invasive than pulling the carbs apart. Carburaters scare the @#^^ out of me and I think I will leave that to the professionals (at least for now). Thanks again.