1989 Evinrude 140hp rough idle

[PhatCrewy]

Hey guys i have done a lot of work to my outboard but she still seems to have a rough idle. Now im not sure what constitues as a "good idle" for these old girls so i have uploaded a video
HERE. It feels like she is still missing and causes a slight unbalance and is also very smokey. I am running 50:1 oil FYI. If I rev her up and return to the idle position in gear she will have a cough and stall and when bringing her up to around 1000 RPM she also has a cough or sneeze. I checked all the electrical and she was firing spot on the whole time and i have checked that the spark jumps the 7/16 gap so i feel its fuel side. 115psi on all pots so i dont think its that. I have conducted all of the link and sync except for the the max spark advance and its all spot on. I am going crazy trying to sort this out. I have rebuilt and cleaned the carbs and ensured all the passages are clear using a single strand of wire the only thing i have not changed is the reed valves although i do have some coming along with some smaller idle jets. Any experts like to weigh in ?

 

[racerone]

Agreed ----look at the reed valves.----And look for possible signs of damage to the metal crankshaft seal rings.

 

[PhatCrewy]

So I pulled off the carbies again. They did not seem warped. I removed the throttle body and put some sealant around the plugs and cleaned up the face as I found some small scratches around where the idle port of the o-ring would sit. I also had a peak into the reed valves but nothing stood out. I then reassembled and ran it on the muffs. Still seems no good. I gave each carby a squirt of start ya bastard and each one responded by lowering the rev and smoothing out so still head scratching. Yes the crankshaft seal rings are possible but as this is a second powerhead and i found no evidence of damage on the other powerhead rings im hoping its not them. All the recirculation system is brand new so not that. The only thing i can think of is that due to the age of the motor maybe she needs some smaller idle air jets. Or somehow there is an airleak on the fuel side

 

[Faztbullet]

Make sure the crossbar linking L & R carbs together is correct as they will slip and cause carbs to be slightly cracked open on one side

 

[PhatCrewy]

Thanks Faztbullet I invested quite a bit of time to remove all the freeplay from the linkages and ensured they were both fully closed and opening at the same time. I came out this morning to start the head scratching again and there was a puddle of black sooty oil on the ground under the leg. I am going to work through the evinrude manual fuel system trouble check chart and see if i uncover anything.

 

[racerone]

If a 2 stroke has been idling for some time on a hose you will see a black puddle.----Normal.----Are you test running on a hose or with boat floating in the water ?-----It does make a difference.

 

[PhatCrewy]

I have done both. the muffs was just to see if the small alterations had made a difference. So i started testing my fuel lines for leaks and i found one around an inline filter which i have now fixed. However when i tested it by giving the primer a solid squeeze i noticed the number two carby started leaking. How much pressure should the needle and seat be able to stop ? I pulled it off to have a look and it was clean and the float height was correct according to the manual.

 

[PhatCrewy]

So it turns out that the number 2 seat was damaged and did not seal. I went through and cleaned all the carbs again with ultrasound bath and tested all the needle and seats as well as float height. Now it when giving it pressure it is leaking from the water separator filter. The rubber o ring looks fine. Im wondering if maybe I need to move my primer pump to after the housing? Perhaps it does not handle pressure well

 

[racerone]

#2 carburetor is the top one on the left when looking at the carburetors. from the boat side.----What primer pump are you referring to.----Picture of the primer pump ?

 

[tphoyt]

I think he’s talking about the primmer bulb on the fuel line from the tank.
FYI my bulb is after the water separator and I don’t have any problems.

 

[racerone]

Leaks on fuel lines are bad.-----If between motor fuel pump to inside the tank air will be drawn in.

 

[PhatCrewy]

#2 carburetor is the top one on the left when looking at the carburetors. from the boat side.----What primer pump are you referring to.----Picture of the primer pump ?

Yes that is correct it was #2 with the bad seat. I was referring to the hand primer bulb. It is currently before the water fuel separator which has a clear drain bottom that is leaking when i pressurize the line. so i think i might move it today so that i will have tank to water separator - to hand primer bulb to inline filter to motor fuel pump. I also went ahead and sanded all the carbies flat to ensure they weren't drawing any air due to being ever so slightly warped. Also i just relised that no one may have had access to watch the video of her idling so i have redone the link here that should work. This is the initial idle i have not run her back in the water as of yet.

 

[PhatCrewy]

So after I swapped the components around I primed it up to get rid of all the air in the lines and then ran her on the muffs. Seems better but still has a intermittent lean sneeze. It nearly stalled the engine. Is there a way to test the crankshaft rings without removing the powerhead? I am very confident in the recirculation system and the fuel system.

 

[PhatCrewy]

Ok so i have narrowed it down to #1 that is causing the lean sneeze. I pulled off the carby and rechecked it everything was clear and fine. i checked compression which was good. I checked spark which was good. I then swapped #3 carby to number #1 no change. swapped the #3 spark plug to number #1 no change. So im convinced its not a carby issue or an electronic issue. I will also swap the coil just to rule that out as well. So right now with the spark plug disconnected on #1 it idles great considering its a cyclinder down as soon as i put #1 plug on she coughs and pretty much stalls. I will recheck the recirc as i messed around testing that the other day. It seems more promident than it did before. Maybe the #2 running rich covered it somewhat ? or i have done something. This is like wack a mole

 

[PhatCrewy]

Sorry this is sort of a running commentary but i just want to write it down as it happens so someone with more experience can pick something up hopefully. I rechecked the recirc and found everything to be in good order. I tried to spray some fuel in each carb and found that on all but #2 the engine rpm dropped. However, #2 engine rpm increased and no misfire from #1. I dont want it to be true but does this sound like an indicator that the crankshaft seal ring is not doing its job? By making number #2 rich anything that leaks to #1 would make the mix richer not leaner stopping the lean sneeze ? This is why i did not notice it as much before because #2 needle and seat was leaking which would of made it run rich? My other theory is that #2 is now too lean causing the revs to drop and maybe throwing the timing out. Because giving #2 the fuel increased the revs and feeding fuel into #1 usually made it stall not increase revs.

 

[racerone]

Sounds like #2 carburetor is not supplying fuel.-----A carburetor is a simple device that responds to airflow.-----Step # is to have a really good look at the #2 carburetor.-----Top cylinder is #1.------Highest carburetor feeds #1 cylinder.-----Remember that these carburetors " cross over ".------The ones on the left side feed cylinders on the right side !

 

[PhatCrewy]

Sounds like #2 carburetor is not supplying fuel.-----A carburetor is a simple device that responds to airflow.-----Step # is to have a really good look at the #2 carburetor.-----Top cylinder is #1.------Highest carburetor feeds #1 cylinder.-----Remember that these carburetors " cross over ".------The ones on the left side feed cylinders on the right side !

Yes you are right i have been looking at the wrong carb! That makes much more sense! time to do some more looking.

 

[racerone]

No surprise to me.

 

[PhatCrewy]

I owe you a beer racerone lol. I pinched the ring. However now I have replaced it and she is not spitting anymore. However, still rough idle and after removing the spark cap from #2 there is no drop in rpm. However all the others cause it to drop rpm. That is top lh side.

 

[PhatCrewy]

Got some more starting fluid and gave it a squirt in #2 carby and the rpm increased and then misfired and then went back to rough idle. I will swap out another carby to see if it is still a carby issue otherwise I guess I am chasing a vacuum leak.