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Evinrude 5.5 won’t idle

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bigtime_mcalpine

Regular Contributor
Hi guys,
I think I need some ideas.
working on this motor: it starts, it revs beautifully, it will maintain nice smooth rpms with a bit of gas but it won’t stay even at idle and just sputters out. Carb kit installed this season. I’ve attached three videos to show you what I mean. I thought you would be able to hear me speak in videos but apparently not.

First video: looking to show you that I can’t quite get the right adjustment on the idle knob. I just begin to hit higher revs when I have the adjuster fully screwed in!
https://youtu.be/Sh_Hesbp8Jk

second video: trying to show you where throttle and follower sit when the engine starts to struggle
https://youtu.be/x00-lBy52bw

third video: close up of follower when attempting to idle.
https://youtube.com/shorts/NFAf7k5hKZQ
ideas? Thing runs like a top otherwise. This is frustrating.
 
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Ok. I watched the video's, but I hope I didn't miss anything. First off get a fan and suck/blow the exhaust away from the motor. The exhaust will skew your settings.

When you adjust the low speed needle, you have to slow the motor down at the same time. Or you can miss the "sweet spot". The way I did my dads 1959 Evinrude 3hp was start at 1.5 - 2 turns out on each needle. They run awful, but then turn clockwise 1/8 turn or less and wait 5-10 seconds for the engine to change. Some may respond faster than others. But each time you adjust it leaner, it will rev, so you need to turn the throttle down, eventually you hit the area where it idles no lower and it does the lean low idle stumble. Then I gave it 1/4 turn rich (CCW). After the bucket test I fine tuned the setting on the lake.
 
Does spark jump a gap of 1/4" or more on both leads ?------Does throttle plate open at the correct time ?-----Post the compression numbers here.----Have you checked for a hole in fuel pump diaphragm ?-----Have you inspected the thermostat ?-----Motor sound awful to me.
 
Ha! Runs great.........for one cylinder. Once you get spark to the other cylinder, then tighten that low speed needle packing nut so it stays in adjustment. Might do compression test too, just for fun. Nice motor.
 
Thanks, guys. Yep, agreed. Sounds awful...at idle anyway. Compression is decent 90 and 95 iirc from a couple of weeks back. Spark is solid. Motor has got no thermostat...there is a spot for it but there is nothing in there. Throttle plate seems to open a hair early based on readings but I don’t think that’s my issue. I have not checked fuel pump diaphragm. I’m assuming a hole would be obvious? Given that I’m putting the needle all the way in (lean) I’m inclined to think that there may be a vacuum leak.
 
timguy said:
Ha! Runs great.........for one cylinder. Once you get spark to the other cylinder, then tighten that low speed needle packing nut so it stays in adjustment. Might do compression test too, just for fun. Nice motor.
Click to expand...

Hmmm, you think so? Alright, I'll unplug one plug at a time to see if there is a difference.
 
There will usually be a change in performance when one plug is pulled but the main indicator is did the motor keep running? If it did then all the cylinders are operational, at least to some degree. If it stalled, it means the other cylinder, not pulled, is defective.

Yes. Use insulated pliers to pull spark plugs. The voltage is quite high and does seep through the insulated plug cover. Now you know.
 
Okay now that we've gone over the basics. When you rebuilt the carburetor did you pull the Welsh plugs out and clean behind them? Then second when you put the plugs back in to use sealant on them before you dimpled them down? Because if they leak that leaks vacuum and that will equal the carburetor that's hard to tune.
Now when you reinstall the packing for the needles, did you oil or Grease the packing before you put them in? That will help everything move without sticking or binding. Also did it come with metal washers that help compress the packing evenly? The last one I did the kit did not have those washers so I had to reuse the old ones. Also is your fuel pump in good condition? a pump with a stiff diaphragm will not pump fuel like it needs to at low idle. Lastly go through my first post re read the low-speed tuning procedure. You need to have the engine idling as low as possible before you start adjusting the low needle. Also put a fan by your water buckets and get the exhaust away from the engine so you can tune it properly.
 
All good advice.
Okay, then....I was wrong. Did you check all the things in Racers post #3? If all that will check out, then it could be a poor seal at the little donut in the bottom of float bowl. This can allow unmetered fuel to escape to the high speed nozzle making it very difficult to tune at low speed.
 

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timguy said:
All good advice.
Okay, then....I was wrong. Did you check all the things in Racers post #3? If all that will check out, then it could be a poor seal at the little donut in the bottom of float bowl. This can allow unmetered fuel to escape to the high speed nozzle making it very difficult to tune at low speed.
Click to expand...
Good point Tim, the 3hp I had tuning issues with the raplacement donut that came with the kit and was the wrong one. It was too thick and too big a diameter and it would not seal properly. I ended up using the old one and it worked out just fine. One other thing I was thinking of is check the flange gasket where the carburetor bolts to the engine make sure that was not leaking vacuum as well. And easy test is to spray starting fluid or carburetor cleaner around that seal and if the engine changes RPMs then you might have an issue there
 
Maybe the shock absorber / slip clutch in the lower unit is binding.---I said this motor sounds awful and not near what a " happy " 5.5 HP sounds like.
 
Say, Racer......question? Is there any way these clutch units can fail only when motor is fully warmed up and trolling. The guy returned a 5.5 horse "Golden Jubilee Edition" to me he said it "freezes up" when out fishing, then later on it's okay. I just gave him a different motor. Never even looked at it since.....25 years ago.....it's still here in the shop with the other 200 motors. Man.......if something unexpected happens to me, the wife and son gonna have a helluva auction.
 
Soon there will be private virtual auctions.....kinda like ebay, we need to set everything out, at least enough to get some good views, then a brief discription, then page after page of items.....categorized. Bidders set a cap bid, then wait for the win.....it could happen in a few seconds. Live auctions are too clobbered up. Expensive items would include a brief video of operation/with audio. The better the presentation, the higher the bids. What you think? That way we can "check out", knowing are stuff is in the hands of someone capable.....not some "scrap scrounger".
Now what happened to "Big time"?
 
Well, turns out that the user who suggested it was running on one cylinder was close to the mark: thing had new coils and points on put lower cylinder points where about 1/2” outside of the two vertical timing lines/marks. Went old school with a continuity tester and got ‘er straightened out. Not quite putting yet as the mix screws need some tweaking but sounds a lot better! Thanks for all the help!
 
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Make sure no water is leaking into the cylinders, I have a 9.5 I've been chasing my tail on for forever and turns out it was only running on one cylinder as water was getting in the bottom one, even the slightest bit of water will cause a problem.
 
Yes these 5.5 and 6 hp also had head gasket problems. I think he changed it already. The aftermarket Sierra gaskets are improved over the original ones.
 
That’s interesting. Did you still have good compression results?
I have not yet done head gasket. My compression was good (90/95) so I left it well alone. Should I reconsider?

when we took it out for a test run before something broke here’s what we were experiencing:

idle was “ok”
still could not adjust idle needle, I was able to thread all the way in (slowly) and engine was still getting fuel and it almost seemed like another 1/4 turn would have given me better idle (it had bottomed out so I’m just imagining). As it was it had not yet gone through the higher rev/lower rev cycle which would have prompted me to ease back off and hold.

it would not accelerate properly and it bogged down. I was able to get throttle fully opened long enough to adjust high speed needle. When I did that, boom, it took off. So I though, damn, nailed it! Nope. Brought it back down to idle and smoothly rolled throttle to get back to high Speed and it bogged down again. This happened a few time where the only way to get it to perform at full throttle was to adjust the needle on the fly and then it would react.

ive put two different carbs on there thinking maybe it’s a carb issue. Both behaved exactly the same way. It seems like it’s a “too much fuel” bog down but not sure why that would be. I check pump diagram and no fuel is coming out back. Maybe I’m wrong.
 
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It had 60 psi in both cylinders, it ran on both for a while but would die as soon as you took choke off, I have pulled the plugs out a couple times and they were dry, pulled them one more time to check for spark again and the bottom one was dripping with water
 
That's okay (fair) compression....depending on your gauge, for a 9.5. they are not as high as the old 10's.
 
Update:
I’m embarrassed to say that it may very well be that I had the wrong plugs on there. They were shiny new from previous owner so didn’t really look much closer...They were NKG J8S when they should have been NKG J6S (I think I’ve got that right). Anyhow, bottom end is off, I replaced the head gasket for kicks, put in new plugs gave her a go and idled decently. Had an issue with the bottom end and having now taken it apart it appears that my clutch dog had bit the tit.

I have noticed a bit of oil leaking from top of crank. Has anyone replaced top seal on this thing? A review of marine engine.com parts diagram shows this strange looking seal that I”m at a loss on how to remove.
 
The " strange looking seal " might be a slinger.-----They work well , never wear out.------It is pressed onto the crankshaft.
 
racerone said:
The " strange looking seal " might be a slinger.-----They work well , never wear out.------It is pressed onto the crankshaft.
Click to expand...

It IS a slinger - with that in mind would you recommend not touching? I thought there might be an oil leak up there but maybe someone just go liberal with grease...
 
The slinger will never ever need to be replaced.-----And don't pack grease in there as that will make it leak worse !!----You should study how this elegantly simple stuff works.
 
Are you still working on this thing?
Here is a quote from another tech, explaining this sweet and simple "seal".
 

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