6 hp evinrude running rich at high speed

[45calmuzzleloader]

I have a 1970 6 hp evinrude, it idles ok, but give it more gas and it is way rich. Carb has correct fixed high speed jet. Carb has been rebuilt w/new float. 90 psi comp. in both cylinders. Reed valves look good. Spark will jump a 1/4" gap. Any ideas what could be wrong?

 

[Cap'n Chaos]

Re: 6 hp evinrude running rich at high speed

I'm no expert, but hopefully one of them will chime in soon...

Are you sure you set the float height correctly?
Did you clean the carb thoroughly?


See this link:

http://forums.iboats.com/showthread.php?t=244013

 

[merc20076]

Re: 6 hp evinrude running rich at high speed

I have a 4.5HP 1984 and it does exactly the same. Runs way to rich at WOT. Smells crazy 2 strokes smoke.

I have done on it and nothing better after:

New carb kit
Decarb
New sparkplugs

The compression is very low, 75 PSI on both cylinders, this is why and sometimes it won't reach WOT.

I think I will have to do a piston rings job/crankshaft seals on it if it's not to hard to do.

 

[45calmuzzleloader]

Re: 6 hp evinrude running rich at high speed

When I rebuilt the carb I removed/replaced the little "freeze plug" on top and removed/replaced the lead shot. Well soaked in cleaner, ran copper wire+blew compressed air thru all passages, reassembled with new carb/float kit. Adjusted new float according to 1970 Evinrude service manual instructions. When I unplug the fuel connector and just before the gas runs out for a few seconds it runs like a dream. My motor bogs and smokes alot when the throttle is opened. Does 90 psi comp. sound low? I bought a can of Seafoam. Should I try decarb treatment? I have been working on outboards since I was teenager and I am stumped.

 

[AlTn]

Re: 6 hp evinrude running rich at high speed

if you're positive the float level is correct..is the needle valve sealing in the seat or possibly sticking open slightly...with the carb off the motor, did you try to blow into the fuel nipple to see how much pressure it took to lift the needle off the seat several times in succession..in fact, you can do this with the carb still on...just use some spare fuel line

 

[Cap'n Chaos]

Re: 6 hp evinrude running rich at high speed

Where I had problems was with the old packing around the slow speed needle, and the fact that the needle itself was worn...


Did you install the little "spring clip" that attaches to the arm of the float and needle when you put in the new carb kit? (The needle has no choice but to move with the float when the clip is installed.)

 

[45calmuzzleloader]

Re: 6 hp evinrude running rich at high speed

I have not tried testing the float in that matter, gonna try that next. I installed 2 new brown packing rings and inlet valve clip/seat/needle. Packing nut is tight, but I can still turn the needle. I put a new sierra fuel pump on it and new fuel lines and bulb from the tank all the way to the carb. I had to rotate the new fuel pump cover/screen to get the hose in the proper place. Maybe I boogered up the fuel pump when I did that. I need to locate a schematic for the pump, and reassemble it as it came out the box. Is it possible to assemble the fuel pump incorrectly and make it pump so much gas the float can't regulate it?

 

[AlTn]

Re: 6 hp evinrude running rich at high speed

if all you did to the fp was change the orientation of the cover it's highly unlikely you affected the pump...put a piece of fuel line on the outlet, pull the sparkplugs, and pull it through a few times...I believe it only calls for 1 psi at idle and <1.5 psi at 3,000 rpm...