2-stroke 25HP mercury stalls while accelerating.

[Apex Predator]

I had a similar issue recently with a 97' Merc 25. After replacing fuel line, bulb, and fuel filter in the engine, the problem persisted. I turned the tank upside down, opened the tank cap vent, and drained some gas into a clear jar. I had half gas and half water! I replaced the tank, and she runs like a swiss watch now.

 

[Jay415]

WHAT A RELIEF!!!

I was really nervous that I made a bad purchase with this motor. I was getting 90psi compression in each cylinder. I got my service manual in and specs say that compression should be 120psi or better. Well, the big, big mistake I did was buying a compression gauge from Harbor Freight! I read the reviews on it after I bought it #-o It got horrible reviews! I mean bad! not one person claimed it gave an accurate reading! So I stopped by Pep Boys and picked up a new Actron compression gauge and Bam!!! 135psi in each cylinder!!! SO so happy!! I really though I f'd up with this one! Now just waiting for my carb kit to come in and this thing should purr like a kitten!

 

[Jay415]

I broke down the carburetor to clean it and it really wasn't that dirty. A little bit in the fuel pump and around the main jet but not in the port. I sprayed everything down and through all ports and openings with Gum Out carb and choke cleaner. Just waiting for the kit to come so I can rebuild it. The main jet was really tight in the plug and I slipped with the screw driver, stripping it a little. Should I replace the main jet or will this be ok?

Edit: the main jet is $3 on boats.net. I just ordered a new one and a new plug as well. Why take a chance with something so cheap!?!?

 

[Jay415]

Ok here's a stupid question. I tried paying attention to every little detail, but I missed this one. (prob due to the gas spilling all over the place when I took the bowl off :lol

Which way does the float go? 1 or 2? Or does it even matter? I'm guessing 1.

1


2

 

[Buddychrist]

#1 that's how it would get a seal on the bowl

 

[Buddychrist]

Did you let the carb sit overnight in chemdip before rebuilding?

 

[Jay415]

No just the acetone spray. Even though it didn't look dirty, it looks almost brand new now except for a little green around brass parts. I didn't rebuild it yet. Kit is expected to be here on the 31st.

 

[Jay415]

What do the bleeder hoses that come from the reed block cover and go into the side of the cylinders do? I noticed the one on the bottom cylinder is wet with oil around it at the cylinder. Not a lot, but the top one is bone dry.

 

[Jay415]

In the primer chamber after removing the brass plug, there is a spring, then a silver ball, then a split ring and a rubber o-ring.

How do I get that split ring out? I tried picking it out with an awl.

Also how do I get the new one in?

 

[Buddychrist]

That might not need to come out, when you get the kit in you'll have the instructions and it will tell you how to remove it

 

[Jay415]

I was hoping for instructions but they didn't come with any. The kit came with new red o-ring and split ring along with the spring and silver ball.

The one still in the carb looks good but I'm just afraid I softened it when I cleaned the carb out with the acetone. I was amazed on how it disintegrated my vinyl gloves. I tried not to get the acetone on it though.

I posted the question on boats.net mercury forum also.

 

[Jay415]

Ok I was able to pop it out. Getting the new one in is gonna be a challenge. I'm glad I got it out though. It was all caked up. Def not as clean as it looked.

Most of the pieces from the carb looked pretty good except for the diaphragm from the fuel pump. Now that I see the new one, the old one is really stretched out.

 

[Jay415]

Ok carb all rebuilt. I adjusted the carb, timing, throttle linkage, etc. all to factory specs. Runs great! Just have to do a little fine tuning on the idle air mixture. All in all I am very happy and relieved about not making a bad purchase! Thanks for everyone's help! Especially Buddychrist!

Before
[youtube]0RqT_ProdOc[/youtube]

After (it's a little dark cause I went out when the sun was setting)
[youtube]scnPOdhRE7E[/youtube]

 

[Buddychrist]

No problem at all man!

The difference is night and day isn't it? That thing sounds great! I bet your pulling 24-25 mph with it!


How do you have your friction plate set? I'm still working on getting mine set and it seems I've either got it too tight or too loose.

 

[Buddychrist]

Also just a tip when checking compression on any engine you have it done at full wide open throttle. Sorry I forgot to tell you that when you were checking your compression.

But man that motor sounds just as good as the one I have if not better!

 

[Jay415]

By myself I get about 26-27mph as per the gps. The friction plate for steering? I have that right in the middle.

Does this mean the motor is running too rich? It didn't do this prior to rebuild. Prior to rebuild there was just a few drips. I know some is normal. This was under the motor.

 

[Buddychrist]

Do you have Oil coming out of the carb?

Or is that from the foot?

If its coming from the exhaust you could have a bad seal that can get worse if it dries out unsealed.

 

[Jay415]

Mixed not injected. Not sure what you mean by the foot. It appears to be coming out of the thru-hub exhaust by the prop.

 

[Buddychrist]

Ok that clears it up for me, run a full can of seafoam through the motor and then lower down your idle and high jets just a 1/8th of a turn

 

[Buddychrist]

Just make sure if you ever get a gray or milky oil residue from the lower unit means a bad seal.

Black oil is normal that's unburnt fuel, seafoam will smoke like hell but it will burn all the carbon from the engine and give you a cleaner burn. Also get your hands on non ethanol premium unleaded, they run 10x better on it. Don't use gas station oil but get some 2 stroke PWC oil from quicksilver, it's got a higher lubrication and runs real smooth on an outboard.