Johnson 50 won’t idle, unburnt fuel in exhaust water

[JerEazy]

2000 Johnson PLSSM

i can get the engine to start by manually opening throttle butterflies. But she smokes like mad and there’s unburnt fuel coming out of the exhaust. Here’s what I’ve done so far:

compression 120 on both
verified spark jumps 7/16 gap on both cyls
verified WOT timing using joe reeves method
rebuilt both carbs (done these style of carbs many times. They were in very good condition when I pulled apart)
new spark plugs
cleaned grounds
hooked to external tank for testing

its as if she’s flooding out. When I went to retest I didn’t hook the tank up and it actually idled for a few seconds before she ran out of gas.

Advice appreciated.

floats set wrong maybe?

 

[JerEazy]

Pulled the carbs off and re verified floats. Typing they made me think of it. Still no dice.

 

[JerEazy]

Disconnected one spark plug at a time and remote started with butterflies open and confirmed it will run on either cyl that way.

 

[Cheeze75]

I'm having same issue open butterfly's and I can keep it running got a 69 evinrude 55hp its flooding out exhaust stalling at idle I was thinking floats to but maybe the idle circuit in the carbs didn't get fully cleaned ( I didnt remove cap on top and clean from that side. thought removing needle and clean from that side would be enough. I may have miss something.

 

[F_R]

I don't know what's wrong with you guy's motors, but opening the butterflies at idle (retarded spark) is making the fuel/air mixture much leaner. In fact it should stall if you do that.

 

[JerEazy]

I don't know what's wrong with you guy's motors, but opening the butterflies at idle (retarded spark) is making the fuel/air mixture much leaner. In fact it should stall if you do that.

So if it doesn’t die it’s because got too much fuel?

im wondering if the fuel pump may be leaking?

 

[F_R]

A leaking fuel pump diaphragm certainly will flood the one cylinder that it is mounted on, but have little effect on the other ones.

Please, we seem to be discussing two very different motor here. Let's keep the issues separate.

 

[racerone]

When you get a ---" new to you motor " you have to do the basics.----Check flywheel key.----Compression -----Reed valves.----Spark intensity------Hoses -----Fuel pump.----Fuel tank.-----Sometimes there is a reason that a boat / motor is sold.-----Carburetor rebuild does not always fix it !!

 

[JerEazy]

When you get a ---" new to you motor " you have to do the basics.----Check flywheel key.----Compression -----Reed valves.----Spark intensity------Hoses -----Fuel pump.----Fuel tank.-----Sometimes there is a reason that a boat / motor is sold.-----Carburetor rebuild does not always fix it !!

Totally agree. I’ve done those things and still seem to be coming up empty.

as I said, compression checked, remote tank, spark checked too. Fuel pump is coming tomorrow.

But that seemed like a stretch. That’s why I posted.

 

[racerone]

Fuel pumps are so easy to test / repair if need be.----What pump is on this motor ?----VRO or something else.?-----I can not believe anyone would invest in a new pump without some basic inspection / testing.

 

[oldboat1]

Might need starter work (not spinning the motor fast enough) -- may simply need to be disassembled and cleaned, or wiring connections cleaned. With boat battery and wiring hooked up normally, key on, jump starter directly from your truck (positive cable to post on starter, negative to bracket). See if the motor starts that way -- but never by simply opening just the throttle plates, though, or you risk a runaway engine.

 

[JerEazy]

Fuel pumps are so easy to test / repair if need be.----What pump is on this motor ?----VRO or something else.?-----I can not believe anyone would invest in a new pump without some basic inspection / testing.

It’s a standard Sierra fuel pump. VRO was bypassed by previous owner. At ~ $20 to replace I wasn’t overly concerned and would consider the replacement maintenance expense.

im in a bit of a rush to get her going because I promised to take my daughter fishing tomorrow. So I’ll ask you to excuse me slinging parts at it.

 

[JerEazy]

Might need starter work (not spinning the motor fast enough) -- may simply need to be disassembled and cleaned, or wiring connections cleaned. With boat battery and wiring hooked up normally, key on, jump starter directly from your truck (positive cable to post on starter, negative to bracket). See if the motor starts that way -- but never by simply opening just the throttle plates, though, or you risk a runaway engine.

I’ll give it a shot. But the motor does start if I advance the throttle in neutral. And will stay running if I leave the throttle advanced.

 

[JerEazy]

Fixed!

gaskets under the plastic cover on top of the carbs were wrong way.

when in doubt, do it again.

 

[hardwater fisherman]

I did something similar on my 25 hp merc.. I put the intake gasket of the carb on the wrong way and covered up the hole that makes the fuel pump work..

 

[JerEazy]

Glad she’s mechanically functional now.

next is the electrical system.