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PostPosted: 21 Sep 2016, 23:18 

Joined: 11 Jan 2012, 10:26
Posts: 283
Location: Albion, IL
I got a 84 25hp Evinrude that sneezes at idle. It use to do it every once and awhile just at idle. Its gotten worse to the point it wont hardly idle. I have cleaned the carb 3 times. First time was soaked in carb cleaner with the plugs out and I ran tip cleaners thru every passage and sprayed carb cleaner and air thru them. 2nd and 3rd was with carb cleaner and air. New kit with float. Its running lean. The top plug is wet and bottom one is dry. Is the bottom crank seal leaking air? Thats the only thing I can think of causing this. I have replaced every rubber line on it. Tried different spark plugs. changed the coils from top to bottom and still wet plug on top and dry on bottom. If you put your hand over half of the intake on the carb it runs better but not great. Anyone got any ideas? I think its the bottom seal leaking air.

Thanks
Steve


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PostPosted: 22 Sep 2016, 09:02 
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Joined: 15 May 2010, 00:38
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Location: Central Florida
When it sneezes lean can you feel the pop coming back through the carb?
Have you looked along the crankcase parting halves for evidence of a leak there?
Possible leaking gasket on the intake by-pass cover on #2.
If that is the cyl the fuel pump is on then check the connections there.
This should give you a few things to check before pulling the powerhead and doing the seal.


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PostPosted: 22 Sep 2016, 14:18 

Joined: 11 Jan 2012, 10:26
Posts: 283
Location: Albion, IL
I dont feel it pop back thru the carb. I havent seen it leaking around the crank case halves or noticed and around the intake bypass covers. the fuel pump is on top cylinder bypass cover. i thought it might been leaking and making the top cylinder run rich and thats why the plug is wet but i dont think its leaking. it runs great just idle it sneezes bad. I have the powerhead off now to look at the bottom seal. it appears to be a single lip seal and the new ones are double lip?

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Steve


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PostPosted: 02 Oct 2016, 09:35 

Joined: 11 Jan 2012, 10:26
Posts: 283
Location: Albion, IL
I changed the seal and the hose that came from the top bearing to the bottom bearing. No other signs of leaks anywhere. Still does it just not as bad. I am out of ideas. Any suggestions????

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Steve


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PostPosted: 02 Oct 2016, 18:41 
Donor
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Joined: 15 May 2010, 00:38
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Location: Central Florida
Let me ask a question I should have asked to begin with.
Compression?
Sync & Link? Carb is not open at all at idle is it? Should be closed and running on timing.


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PostPosted: 03 Oct 2016, 22:16 

Joined: 11 Jan 2012, 10:26
Posts: 283
Location: Albion, IL
compression is 120 top and bottom cylinders. carb is closed at idle. i looked in the bore today and double checked it. I took a look at the service manual on boatinfo.no to check the sync of the carb. In the manual is says to use "B" location. the throttle shaft should start to move when the roller is to the starboard side of the mark. Ok Which mark??? theres 2. I guess the first one. So thats where i set it. It ran better but still acted up. So i thought what the hell lets got to the port side of the mark. Ran even better but still sneezed every once and awhile and died. Still have alot of turns on the idle screw out. 3 or 4 out from the seat. I looked into the timing and according to the manual its set at wot in forward gear at 30 degrees. So no timing adjustment at idle, i guess?? Theres what I did to it today.

Steve


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PostPosted: 03 Oct 2016, 23:48 
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Joined: 15 May 2010, 00:38
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Location: Central Florida
Pull your carb again and take a look back into the reeds for the bottom cylinder. See if there is something going on there. You may end up pulling the intake and checking the gasket. But before you do this......
One thing I cannot remember is on the carburetor. Is this one of the carbs that has the idle circuit that comes off the HS then over to the side of the bowl and up the side of the carb? If so then there is no way a simple tip cleaner can be used to clear that passage. Think that carb was an earlier carb but.....check it for me.
Second, did you install a new red needle packing? Did you run a tip cleaner all the way up the center idle pick up tube if so equipped. Did you install a new nozzle well gasket in the carb?


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PostPosted: 04 Oct 2016, 22:21 

Joined: 11 Jan 2012, 10:26
Posts: 283
Location: Albion, IL
I pulled the carb off today. looked at the reed valves. I took a oring pick and lightly opened each one just a bit to make sure none was stuck. Everything looked good in the intake. I tore the carb back apart. The idle circuit is fed by a brass tube that runs up the middle of the carb and is inside the high speed tube. I ran a piece of wire up the idle pickup tube with the idle needle out to make sure it was clear. and it was. when i rebuilt the carb the first time. every gasket was replaced and the plugs taken out and soaked in good quality carb cleaner overnight. I installed the red needle gasket the first time it was rebuilt along with the nozzle well gasket. I never got a chance to start it.

Steve


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PostPosted: 05 Oct 2016, 11:04 
Donor
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Joined: 15 May 2010, 00:38
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Location: Central Florida
Okay....back to looking for an air leak then.
Start the engine and get it to a point that it will sneeze repeatedly and see if you can find a mist of fuel exiting somewhere. In almost all cases the sneeze can be seen if it can be heard. Use a bright flashlight if necessary. Look for a momentary mist of fuel or smoke. Look for a tell-tail trail of blackish looking oily residue as well.


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PostPosted: 05 Oct 2016, 23:28 
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Joined: 15 May 2010, 00:38
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Here is a different path to look at. Timing. Do you have access to a timing light? If so let's do this.
Remove both spark plugs. Take a screwdriver or whatever you can make a mark on, insert it through the spark plug opening and push against the top of the piston and rotate the engine so that you catch the piston just before TDC. Make a mark on your screwdriver. Once you have done this rotate the engine through and when the screwdriver comes up on that mark make a corresponding mark on the flywheel wherever the timing pointer is pointed. Now rotate the engine counter clockwise to the mark on the screwdriver and make the same mark. Halfway between the two marks is TDC. Do the same thing for the bottom cylinder. Make good visible marks at the TDC locations.
Start the engine and take a look at each mark and where the light is. This may show us that your pack or timer base is the cause of the issue. I keep thinking of the black plug and white plug you are mentioning. The added fuel you are throwing at the engine to make it run may be just covering up an out of time scenario. Doesn't cost anything to do this and worth it. The timing light should pick up the top cylinder TDC at the same spot it picks up the bottom cylinder TDC. Obviously you have to change the pick up from the top to the bottom plug wire to see the bottom cyl. mark.


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PostPosted: 07 Oct 2016, 13:35 

Joined: 11 Jan 2012, 10:26
Posts: 283
Location: Albion, IL
Ok I marked TDC for both cylinders. put in the test tank. idle jet set to a round and 1/4 out. synced to the starboard side of first mark as manual says. Hit start button and fired right off. Adjusted idle jet. Ended up about a round and 3/4 out. checked timing with the marks. when it sneezed it was still in time on both cylinders. But now where its set at it idles like it should and dont sneeze and runs. Next test will to be run on the lake. I have no idea on what made it change. Unless the red packing on the needle wasnt seated good. I did bump up the float level a tick but I wouldnt have thought it make a difference in that. Running it on the lake will be the real test. It set and ran at idle for a good 30 min. I would open it up and let it run for a few seconds then back to idle. No sneeze.

Steve


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PostPosted: 08 Oct 2016, 22:07 
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Joined: 15 May 2010, 00:38
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Location: Central Florida
Float height, if just bumped a tiny bit will not have the effect at an idle that you have been writing about. Good luck and let us know.


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PostPosted: 09 Oct 2016, 19:50 

Joined: 11 Jan 2012, 10:26
Posts: 283
Location: Albion, IL
Well I ran it on the lake today. Still does it just not as bad. I will be idling along and sneeze. It might go awhile and do it one or three or four times and die. Seems worse after you have it opened up going across the lake then back it down to idle. Which I figured it would be when it would do it the worst. I am at wits end with this thing. I didnt see any signs of leakage around the crankcase or the intake bypass covers.

Steve


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PostPosted: 10 Oct 2016, 22:28 
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Joined: 15 May 2010, 00:38
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Location: Central Florida
Since it is not as bad as it was before try richening the mixture past the 1 3/4 mark you currently have it set at.


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PostPosted: 11 Oct 2016, 08:45 

Joined: 11 Jan 2012, 10:26
Posts: 283
Location: Albion, IL
I did turn it out about a half round it made it better but still did it every once and awhile. esp when you came from WOT to idle. if you slowly came from WOT to idle it wasnt as bad. Just still something not right. I will try and run it in the tank tonight and adjust it out some more.

Steve


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