Carburation problem ? what u think

[dmarti06]

Hi All,

I'm new to this forum, hope someone can help with this ongoing problem.
1987 60hp Evinrude starves for gas whenever placed in forward at initial takeoff, if I don't backoff it will shutdown. If I press solenoid and give it gas when it wants to shutoff, then takes off and then runs just fine after initial takeoff. Oh also will idle fine without any problems.

1} Allready removed and soaked all three carbs overnight and rebuilt with new card kits. I'm pretty sure that I was thorough and followed instructions on manual and here on forum.

2} Mechanic replaced fuel pump with new one a year back so relatively new fuel pump. He bypassed the VRO so I mix my own oil/gas mixture.

3} Replaced gas hoses from VRO to carbs with new ones and checked for any gas/air leaks. All ok.

4} Have replaced gas/oil mix. and cleaned gas filter.

ps: Adjusted linkage as per manual but haven't checked with timing light on water since not easy. Do you think it could be linkage misadjusted?

please help really frustrated .......

 

[Silvertip]

Re: Carburation problem ? what u think

Do these carbs have idle mixture adjustment screws? If so, you need to richen the mixture a little. Hole shot issues with a two-stroke are generally due to a mixutre that's too lean. If the carbs are not adjustable, then there are other issues that you overlooked during the rebuild. All passages and jets need to be squeaky clean.

 

[dmarti06]

Re: Carburation problem ? what u think

On this model they are fixed jets and carbs don't have any adjustments. As mentioned, I removed all carbs and dis-asembled plus even removed core plugs and soaked for entire day, then took wire strands from cable and checked passages for any clogs. squeeky clean!

 

[F_R]

Re: Carburation problem ? what u think

Watch the throttle linkage on the side of the motor as you advance the throttle (not running). The spark advance must go all the way up against the full advance stop bumper before the carb butterfly valves dump open. The spark advance part is driven by a spring in the big throttle lever assembly and if it is sticky, the carbs will open too soon and the engine will fall on it's face during acceleration.

 

[dmarti06]

Re: Carburation problem ? what u think

I still haven't figured out what is causing this problem, however I haven't checked the last suggestion since not really sure I understand how the linkage works and what is meant by full advance stop for butterfly valves to open. I will look at the linkage assy. with the manual to try and figure it out.

Now it is not doing it all the time though. If I have in neutral idles fine, and I engage in forward and kick it almost full throttle it will take off and not starve for gas(takes off) however, if in neutral and put into reverse ok but when I put back into neutral and then try to engage in forward, it will bog out and shut off if I don't engage the solenoid and give it gas. So you could be right about something sticking with linkage assy.

 

[jtexas]

Re: Carburation problem ? what u think

this isn't your exact motor, but should be similar.........when you advance the throttle lever, the cam needs to hit the roller right on the mark. Also the timer base should move smoothly without sticking.

check to make sure the throttle valves are parallel throughout their range of motion.

 

[F_R]

Re: Carburation problem ? what u think

It's a lot easier to see than to explain. With the manual you should be able to figure it out. But I'll try again. Watch the throttle linkage as somebody gives it the throttle (not running).

There is a vertical main lever that operates the timer base under the flywheel. There are also linkage parts connected to a cam that opens the carburetors.

As you advance the throttle, most of the movement is with the timer base, with just a bit of movement of the carb cam. The carb cam must not move without the timer moving at the same time.

When the timer gets to full advance it comes up against a rubber bumper which prevents any further movement. Then, and only then, the carb cam will move big time and open the carbs wide open.

The problem comes when the carbs try to open full before the timer is at full advance.