Rebuilt Carburetor… Still No Idle!

[CaughtLooking]

I recently bought a 6hp ‘89 Evinrude (e6rcec), it is one of the models with the primer pump instead of the standard choke. It fires up on 1-2 pulls with the primer plug pulled out all the way. It will then idle with the primer pump pushed in halfway as long as I want it to. As soon as I push the pump in, it will slow down until it eventually dies about 30 seconds later.

Compression is about 90 in both cylinders and it has spark. I replaced the old fuel lines when I first took the carb off. When I went to rebuild the carb I found that the old flex tube that connects to the nozzle well was in about 7 pieces inside the bowl.

I meticulously cleaned the carb with an ultrasonic cleaner, spray cleaner, brass wire through every tiny hole, blew it out with an air compressor and then rebuilt with a new kit. The issue persisted and I rebuilt it a second time… still no results.

The idle issue still points me to the carburetor but at this point I know its pristine in there. Could this be an issue somewhere else? I’m not sure where to go next.

Thanks to anyone that can help!

 

[jimmbo]

Welcome to iboats

Is the Float set correctly?
You say you used a Kit? OMC/BRP or some other brand? What parts did you replace?

 

[brodmann]

#15 in this diagram is your idle mixture screw, have you adjusted that? What are your RPM's at idle? Are you trying to idle it down too low? 90
psi compression is a bit low.

 

[CaughtLooking]

Welcome to iboats

Is the Float set correctly?
You say you used a Kit? OMC/BRP or some other brand? What parts did you replace?
View attachment 387921

I belive I set the float correctly. The flat face on the float is level to the milled face.

According to the numbers here I replaced 7, 11, 19, 20, 21, 23, 26, 27, 29 and 38.

This carb was rebuilt before I bought it and the parts inside were already aftermarket. The kit I used was from ROP SHOP, maybe I should buy the OMC one?

There is one piece that is not on that diagram that I’d like to replace. It’s a brass tube with 4 holes that connects from the carb through the nozzle well down into the bowl. It has some wear. Any idea where I can find that?

 

[CaughtLooking]

#15 in this diagram is your idle mixture screw, have you adjusted that? What are your RPM's at idle? Are you trying to idle it down too low? 90
psi compression is a bit low.

I’ve tried that idle mixture screw everywhere from 1 turn out to 5 and it still shuts down on me. Unsure of what the rpms at idle are. When the primer pump is half out, regardless of how smooth, I can get it to stay idling pretty much anywhere in that range from 1 to 5 turns. As soon as I push back in the motor revs up and then dies.

 

[jimmbo]

This carb was rebuilt before I bought it and the parts inside were already aftermarket. The kit I used was from ROP SHOP, maybe I should buy the OMC one?

There is one piece that is not on that diagram that I’d like to replace. It’s a brass tube with 4 holes that connects from the carb through the nozzle well down into the bowl. It has some wear. Any idea where I can find that?

That brass tube, may have been a part of the Carb Body, that wasn't supposed to be removed. Maybe the previous "rebuilder" somehow pulled it out and didn't get it back in properly

Most OMC Carbs, set the float by

 

[CaughtLooking]

That brass tube, may have been a part of the Carb Body, that wasn't supposed to be removed. Maybe the previous "rebuilder" somehow pulled it out and didn't get it back in properly

Most OMC Carbs, set the float by

Yes thats how I have it set

 

[flyingscott]

Did you soak the carb? Spark on both cylinders? Compression is fine at 90 psi

 

[CaughtLooking]

Did you soak the carb? Spark on both cylinders? Compression is fine at 90 psi

Yes and yes

 

[1960 Starflite]

I'm just throwing this in the mix. I have Mercury's both 4 cyl 2 stroke. The idle speed is set by TIMING.

 

[harp2822]

90 lbs is too low

 

[flyingscott]

90 lbs is too low

According to who?

 

[ct1762@gmail.com]

80-90psi these will run quite happily. the primer: disconnect the tiny primer hose going into the intake and plug it with a screw or whatever after the motor is warmed up. if the issue goes away, time for new 0-rings in the primer housing. did you try pumping the bulb to see if it will stay running? if it does, its a fuel restriction or pump rebuild issue. also check condition of slow speed needle.

 

[brodmann]

Idle speed is not set by timing. Idle speed is set by the idle adjusting screw. If you follow the link and sync correctly, you set the timing and carb adjustments separately. Yes, the timing and the opening of the carbs are syncronized together, but timing does not determine idle speed. I set my timing at 4 degrees ATDC and I set my idle speed at 750 RPM's idling in gear. They are separate settings. Once the timing and the idle speed are set correctly, as I move the throttle forward, the timing advances and the carbs open up at precisely the correct time and they work together to achieve maximum RPM's.
That tube that goes down into the bowl of the carburetor is the Emulsion tube. It's brass, right? Has a series of holes in it, right? I've never known anyone to replace those. On some motors, they screw out, but I'm not sure why. A decent carburetor cleaner will make those look like new. I'll mention again that if you didn't remove the jets and blow compressed air through them, you didn't clean the carbs. You need to also hold the up to the light and make sure you can see a perfectly round hole.

 

[jimmbo]

Idle speed is set by retarding/advancing the Timing, which, Lo and Behold is linked to the Idle Stop Screw via the Linkages,. All the Idle Stop Screw does is Limit how far the Timing can be retarded

 

[racerone]

Item 26 is a rubber tube.

 

[rolmops]

If it takes half a minute for the engine to die, then your problem is not the carb,but the fuel supply to the carb. This can be because of a small leak in the fuel hose or the connector, causing the pump to suck air. It may be a clogged fuel filter in your tank. Do check the filter on the fuel pump. it may be full of dirt. I would also do a rebuild of the pump

 

[brodmann]

Jimmbo, you have never been more incorrect.

 

[jimmbo]

Look who's talking...

 

[flyingscott]

Jimmbo, you have never been more incorrect.

How so? provide facts for that statement.