1989 evinrude 140 hp rythmic cough / sneeze.

[PhatCrewy]

Hey all! So I am trying to sort out a rhythmic cough/ sneeze issue on my outboard. It seems to be every two to three seconds and causes a drop in revs and a shot of smoke. So from i have read its caused by a lean condition ?. The carbs are not adjustable and its doing it at idle and through the mid range so i don't think it would be timing. This has all been happening running on the muffs. What is the best method to find the issue. Is it worth trying to disconnect spark leads to see if that makes any difference to try and find the issue cylinder? any guidance would be great. No water in the fuel and the fuel is new. Oil and fuel is premixed.

 

[PhatCrewy]

UPDATE: i took a video and will upload it soon. I also used the fuel primer when it started to cough and it definitely stopped the cough and lowered the revs. So i am going to assume a carb issue. I will try and disconnect a spark plug at a time to see if i can notice a difference. I will also use my infer red gun to see if i can spot a cylinder running hotter

 

[PhatCrewy]

link to video added

 

[PhatCrewy]

UPDATE: Didn't find anything with temp gun. However, i did find that it looks like it may be cylinder three. When it starts coughing if i gave it a squirt of start ya bastard in that carby it would stop and the rpm level out. Hmm, so now i am perplexed as all the carby and throttle bodies were removed and cleaned twice. So i am not really confident that is the issue. Further, to get my RPM down to 1100 RPM (with quick start off) the adjuster on the starboard side under the flywheel is nearly all the way back and the throttle adjustment handle is all the way in turning the timer base to its maximum. This seems excessive. Maybe my pickup timing is off causing it all to be to lean ? If anyone reading this has a 1989 140hp manual and is kind enough to upload the timing adjustments that would be great. I have tried doing it as per two other manuals but something is amiss!

 

[racerone]

Could be an issue with crankshaft sealing rings.----There are 6 of them ( look like piston rings ) on that crankshaft.

 

[Faztbullet]

You need to trim motor level and in a barrel or tub as it needs backpressure.....it is normal for the motors to idle at 1000-1100RPM on muffs and lean spit sometimes with no backpressure

 

[PhatCrewy]

Thanks for the replies! Ok so is there an easy way to test crankcase pressure? Vac gauge off a fuel primer line or something? My thoughts on the idle rpm was that my idle adjuster (plastic turn handle) was screwed all the way in just to get it at that 1100 rpm. Like it wouldn't drop any further. But I will try get a drum and get it in that and see what happens cheers!

 

[PhatCrewy]

Further with the crankcase seals. Would it not effect two cylinders? as it would leak each way ? unless its the bottom seal i guess.

 

[racerone]

Correct ---The motor has 4 separate crankcases.---I have seen issues with these rings and thought it worthwhile to point out.---I can offer no easy way to check them here.

 

[PhatCrewy]

UPDATE: Ok well I will leave the crankcase seals for now as thats a take apart job that I want to avoid until necessary. So I ordered an ome manual from the USA so I will hopefully see it in a month.I took off carby 3 and triple checked it. All clean and no distortion so not that. I also removed the throttle body and cleaned and inspected it and the reed valves. They all seem to be in good order.

Now I'm back at the timing pick up. The seloc manual is useless for this. It just says to back off the top screw on the throttle arm make sure the cam isn't touching. Then adjust it back. I did notice that the cam had solid contact with the throttle plate. ? Is there suppose to be a slight gap? I would think that as they are not adjustable that they would be in the idle position with no contact with the throttle plate?. I made this happen and it definitely dropped the idle down. And was a pretty rough idle but no cough just all equally ruff haha. It was sitting at about 900 -1000 rpm. Now I lined the center of the cam up with the throttle plate and adjusted it so it was close and just touching ensuring there was no force acting on it. Now until i get the ome manual I'm not sure about the rest of the adjustment. Any thoughts let me know

 

[racerone]

Throttle plates have to be closed at idle.

 

[oldboat1]

You need to trim motor level and in a barrel or tub as it needs backpressure.....it is normal for the motors to idle at 1000-1100RPM on muffs and lean spit sometimes with no backpressure

+1. Find a big trash can, and run water half way up the leg. Idle only.

 

[Faztbullet]

You know that is a X intake motor...looking at carbs the ones on left feed the port side and vise versa..make sure you checking correct carb to cylinder.

 

[PhatCrewy]

Thanks fazt. I did over look that but as I was putting the starting fluid in to that carb I should be looking at the right intake? Just the cylinder should be opposite? Bin of water comming

 

[PhatCrewy]

Ok so attempt to put in a rubbish bin didn't go exactly to plan. My need to find a 205l plastic drum. Or go put it in the water.

 

[PhatCrewy]

UPDATE: So cough is still there so i conducted a compression check and results are as follows.
1CYC = 100
2 CYC = 98
3CYC = 100
4CYC= 92

Now from what i have read those are within specs of each other. But, I have heard of readings of 140 from new. Is she just tired ? and need a rebuild or am i jumping the gun ?

 

[PhatCrewy]

It was sitting for quite sometime. would it be worth trying to decarb ?

 

[PhatCrewy]

Update: so while I'm still awaiting my OME manual. I have found that the seloc manual at boatsinfo for the 92 - 2001 has a much better section for the timing so I will give that a crack tomorrow. This is due to finding a sweet spot that idled well until I moved it so hoping it's just a timing issue

 

[PhatCrewy]

So got to drop it in the lake for a run and seems ok ?