Chug a lug

Ok. A weekend drive out to Bass Lake, ON proves to be a disappointment. Maybe someone can help me. I will go through my prob and what I have done.

Engine?
1977 Mercury 402 40HP 2-stroke OB motor. (mixing 24:1 with proper Merc OB oil and PetroCanada 87 grade gasoline).

Problem?
Engine seems to not want to run. It almost seems like it is getting not enough gas or possibly too much or even no air. At WOT it goes about 5mph and then it may or may not open up for about 30 seconds and I am up to about 30-35mph and it will fall back in the hole and bog out and chug and chug and cough and die sometimes. It is doing it at any throttle. Low throttle it will go along and sound good then die. In neutral it will do the same thing at any throttle. Nothing seems to be constant except disappointment.

What have I done?
-Carb cleaner sprayed into carb after engine is hot while running. (Dr. Gunk brand. This also kills the engine!)
-Spark plugs pulled and checked and gapped.
-Fuel filter in tank checked for build up. (None noted)
-Tank vale checked. It is functioning as it should.

So... I thought I would post and ask everyone out there who has an idea about outboard Mercs what could be wrong.

-My neighbour says it could be bad fuel lines in motor. (plastic decay)
-A guy up north thought it could be getting too much air??????
-I thought maybe bad fuel pump.
-I considered the plugs but they seemed clean.
-Fuel was in the tank for 2 or 3 weeks. I thought maybe moisture built up in the tank possibly.

I was hoping to avoid costly repairs. I may actually have to learn how to tear this motor down in the little spare time I have. But I thought I would "fish" for some possible solutions to my discouraging problems. Any help is greatly appreciated.

On a happy note... the people who were drawn to my problem at the dockside were given the address to iBoats.com forums. Hope to see some of them here!

Re: Chug a lug

Your engine is a 50 to 1 engine and might not like the extra oil but that not all the problem. Have you checked for spark on both cyls with a spark gap? Does the primer bulb pump up hard? Have you checked to see if the choke is sticking or the manual is on? If you have all this right check to see if gas runs out the carb vent when pumping the ball. I missed, is the tank vent open and to check the fuel filter on top of the carb. Get back

Re: Chug a lug

Me again I forgot to mention some 402 had a filter separate from the carb

Re: Chug a lug

Spraying carb cleaner in the throat of the carbs does not clean the carbs. All the crud that gums it up is in the bowl and the jets....Spraying it in a running engine can also cause damage due to you washing away the oil in the fuel going into the cylinder. Almost as bad as using starting fluid.

Re: Chug a lug

Laddies said:

Your engine is a 50 to 1 engine and might not like the extra oil but that not all the problem. Have you checked for spark on both cyls with a spark gap? Does the primer bulb pump up hard? Have you checked to see if the choke is sticking or the manual is on? If you have all this right check to see if gas runs out the carb vent when pumping the ball. I missed, is the tank vent open and to check the fuel filter on top of the carb. Get back

Click to expand...

1-I thought it was supposed to be run at 24:1 but I will try the 50:1 and see if it runs a bit better. Could the extra oil build up and cause this at all?

2-I've checked the plugs and they are good. Used a gap tool to gap them. Do I just pull them out and try to start the motor to see if they spark?

3- The primer bulb goes hard when pumped. In fact it will flood the carb if I pump it too much.

4- Choke is not sticking to my knowledge. I can put a straw right into the carb from the front of the engine.

5- Fuel drips from a small valve on the bottom of the carb when I pump the bulb too much. ( I can take a pic tomorrow morning of the valve if needed.)

6- Vent is open. Have tried semi-open and fully open.

7- On top of carb? You'll have to excuse me cause I know very little of 2 stroke engines. Where will I find the filter on the carb? This could b a cause of the problem I suppose since I knew nothing about it.

FYI I really appreciate the help here on iBoats for us noobs. Has come in very very handy.

Re: Chug a lug

Update:

I checked compression and is good. New wires on the plugs. Fresh gas with 50:1 mix. Canadian tire brand outboard cleaner additive. (Could not find Seafoam here) and ran it.

It ran bad again.

But... I played with a U-shaped hose near a water line on the right side of the engine (a fuel line) and when I wiggle it it runs great. Leave it alone and it chugs again.

Bad line? Can I use standard neoprene line from the automotive store to replace it?

Re: Chug a lug

I do NOT have a Mercury manual for reference, but it sounds like you have isolated at least part of the problem by playing with the hose/line. Replace it with fuel grade line and you should be okay even if it is a vacuum or crankcase pressure line. Let us know what it does then. Maybe one of the forum experts knows exactly what the suspect line does. Good luck.