'98 Evinrude 30hp miss at idle (video)

[Cricket Too]

This engine has been running fine all season. I pulled the boat out of the water, got it home and hooked it up to muffs to flush it out, it ran no problem on the muffs while flushing. I pulled the fuel line to run it out of fuel because it was going to sit for a few weeks until I could get around to winterizing/fogging it and I hadn't yet treated the fuel to run it through the carb.

Went to start it back up, maybe two weeks later or so and it will barely idle and coughs out puffs of smoke, as you can see in the below video.

https://www.youtube.com/watch?v=vFGd3Us9jvI

I haven't checked the compression yet, but as mentioned this thing had zero issues all season and I suspect running it out of fuel (which I never do) either did something to the carb or fuel pump.

Thoughts?

 

[jrttoday]

checked the plugs?

 

[Cricket Too]

They both looked ok, a little wet maybe (see pic), buy I cleaned them and put them back in and it didn't help any. I realized yesterday that when I pump the primer bulb it never gets fully hard and I can continue to squeeze it and hear it in the carb, so maybe the float/needle is stuck open, gonna try and tap the float bowl and see if it helps at all. If the fuel pump diaphragm was ripped or damaged at all would it load up and miss like this or would it run lean since it would be pulling air?

It seems like it's running out of fuel and then all of a sudden gets a burst of it, coughs out a bunch of smoke and idles up and then starts to run out again. My guess it's possibly flooding itself out and recovering or not getting enough fuel consistently...either or. Might just pull the carb and rebuild it as it's not been done in the 3 years I've owned it and no idea when the PO did, if ever.

 

[jrttoday]

disclaimer lol - not being familiar with 30 horse, but in looking at your plugs, that's where I'd start... with your carbs. At least, tear 'em down and heavily spray carb cleaner through all passages, let dry and re-use gaskets if possible. Make certain the floats float!! and set to specs. Also, your low speed jets; are they set correctly or non-adjustable? Since it's an idling problem - that could be the majority of your headache. Take a BC,and see if that resolves the issue :lol:

 

[Cricket Too]

Yeah the plugs looked a bit too wet to me, so I was starting to lean towards it was flooding itself out and then recovering once it clear the cylinder out.

Well it's only an idling problem because it's out of the water for winter. It didn't even have any problem when it was in the water. I bet it wouldn't even idle if it were put in the water. I can bring the RPM up in neutral to like 2500 but it still doesn't sound right.

I think I'm just gonna do the carb and see what happens, probably needs it anyway, might never have been done in 17 years.

 

[flyingscott]

Looks like a lean sneeze how does it run with the throttle turned down to normal idling speed. Because right now it seems like it's idling high. I have an 88 25 hp evinrude will do that if i try to high idle it when it's cold. Also activate the primer that will richen up the mixture a little bit.

 

[oldboat1]

thinking fuel pump diaphragm here.

 

[Cricket Too]

Looks like a lean sneeze how does it run with the throttle turned down to normal idling speed. Because right now it seems like it's idling high. I have an 88 25 hp evinrude will do that if i try to high idle it when it's cold. Also activate the primer that will richen up the mixture a little bit.

It's idling high because it's out of the water on muffs, it idles at normal RPM when it's in the water. It doesn't really seem like a lean sneeze because it is belching out a big puff of smoke when it recovers, so I'm thinking it's either flooding itself and recovering or running out of fuel and then getting a bunch all at once....either carb flooding or fuel pump diaphragm shot.

oldboat1....have you ever seen one act like this when a fuel pump diaphragm went bad?

Of all the motors and motor problems I've had through my life, I've never had one act like this.

 

[oldboat1]

oldboat1....have you ever seen one act like this when a fuel pump diaphragm went bad?

I had one with a fuel pump problem late this summer -- symptoms were similar. I was getting some smoking on and off, also had some stalling and problems throttling up. (Recovering with a puff of smoke sounds familiar.) The pump diaphragm on mine was whole, but stiff and had taken a set (no tears or pinholes that I could see). With a replacement, the problems went away.

If the carb hasn't been rebuilt in 17 years, it would be good to do that too, of course. But think I would check the pump diaphragm first. If it's lost its elasticity, would just replace it and see if that gets you back to normal.

 

[flyingscott]

Put the motor in a bucket of water and see if it does that. I doubt you are running rich because the idle would slow down and you should see gas running out of the exhaust. The puff of exhaust is because of the misfire trying to push all the exhaust out at once and what is the temp. If it's cold it will look worse than it is. When you run on muffs the motor is running lean because you have no back pressure. Put the motor in the water and see what happens before you tear everything apart.

 

[Cricket Too]

Well I pulled the fuel pump apart just to take a look at the diaphragm and it's not ripped or anything, but it definitely looks like it's taken a set. Not sure if this would impair it's ability to work or not, or to cause the issue I'm having. It's still pliable, but it's definitely taken a set, have a look.

 

[oldboat1]

Yup. Ready for replacement.

 

[racerone]

Find out why the bulb does not go hard.--That is key information.

 

[Cricket Too]

The bulb gets pretty hard now. I realized that when I was squeezing it I started smelling gas pretty bad too. I noticed the fuel line leaking at the engine connector. I cut the oetiker clamps off and cut the fuel line back and re-clamped it. No more leak and bulb gets hard now. Still had no affect on the miss/crappy idle issue.

 

[oldboat1]

but...progress!

 

[steelespike]

Check the spark with a spark checker should jump 3/8" to 7/16".
Sure sounds like a lean sneeze.I think the plugs may be another issue.

 

[flyingscott]

Take the throttle cable off and idle it down.

 

[racerone]

Has the rod that goes from carburetor to the " tower shaft " been adjusted by anyone ??----Report what the compression values are.----Then test the spark properly and report what it is like.--Does spark jump a gap of 3/8" or more with a snap you can hear , yes or no ?-Is there a thermostat installed and is it perhaps stuck open ?---Answers will help folks steer you in the right direction.

 

[Cricket Too]

Well I finally found time to play around with this again. Ended up figuring out that the little o-ring around the check ball in the fuel connector that goes to the engine, was all beat up and not sealing, so the engine was pulling air. The engine/male side has that little point/needle thing on it. Every time I would pull the gas tank out to fill up I would pull the connector off the engine and take the whole hose with me, as the tank would leak fuel from tank connector if I didn't.

Well I guess every time I was putting it back on that little needle was poking at the o-ring, as you have to put it on carefully dead center or else it pokes at the o-ring. Not sure what the point of that little needle is, I've had plenty of OMC's without that on the engine side male connector.

Anyway, seeing as how I had run it for at least 4-5hrs with the issue, (had no problems planing, cruising or reaching WOT), I wanted to make sure nothing was damaged inside. Did a compression check and got about 85 on each cylinder. This is with a Harbor Freight tester so it might actually be higher but in any case they were both the same, which makes sense since they are both fed by one carb. Does 85psi seem low for this engine? It's running fine now, idles great.


Thanks.