25hp Merc only starts w/starter fluid

[wolfee]

I made this comment in someone else's thread but need help/advice with this.

My 25hp Merc will not start (pull start) no matter how many times I pull. One shot of starter fluid (yes I know it's not good to use) and it starts in one pull. I took it to the lake and same deal, once it started it ran and idled over 3 hours perfectly. Once it's off, won't start w/o starter fluid. I actually did the SeaFoam carb/engine cleaner treatment and I thought it fixed the problem but sure enough, won't start w/o starter fluid. Not sure what to do at this point, the carb has been rebuilt(kit) within the last year. Serial # 0C196683

 

[racerone]

There is a problem in your primer circuit of the carburetor.--------If you can not find / fix that then perhaps install a manual primer such as found on older snowmobiles or on many newer Johnson / Evinrude smaller motors.

 

[tlewis1]

Pull that carb again....just because it was done last year doesn't mean it hasn't got gummed up again or wasn't rebuilt properly.

 

[flyingscott]

Your motor already has a manual primer on it. Make sure it is working the plastic bits like to break. Otherwise tear it down and check the primer assembly. Make sure the base gasket is on correctly and blow out the little primer hole.

 

[Chinewalker]

The tiny check ball in there does have a habit of sticking. As noted above, clean it out. You can squirt some carb cleaner through the circuit with the carb bowl off the carb to verify that it's pumping. Fill the bowl a bit, then hit the primer button. Should squirt out the hole on the face of the carb bowl flange.

 

[wolfee]

The tiny check ball in there does have a habit of sticking. As noted above, clean it out. You can squirt some carb cleaner through the circuit with the carb bowl off the carb to verify that it's pumping. Fill the bowl a bit, then hit the primer button. Should squirt out the hole on the face of the carb bowl flange.

Sorry for the stupid questions, but what do you mean my the "circuit"? There's a black faceplate that covers the front of the carb that also has the choke knob connected to it. If I pull out the choke, the primer pin gets fully depressed. If I remember right, there's a screw at the bottom of the primer bowl that has a small spring with check ball. So if I pull the carb again, I don't have to mess with anything other then the primer/bowl? I don't want to have to order another rebuild kit unless it's a must.

 

[flyingscott]

Take the carb off but before you do fill the carb with gas. When it's off push the primer manually make sure gas squirts out of the hole.

 

[wolfee]

Well I'm back. I took the carb off, after pushing the primer pin a number of times manually. I removed the screw from the bottom of the primer bowl and the small spring and ball came out and look fine. There was no fuel in primer area at all. I shot carb cleaner in the primer bowl area and made sure the small hole where the check ball fits was clear. It actually looked perfectly clean but also perfectly dry. I haven't taken anything else apart at this point but what would prevent fuel from making it to the primer bowl? The motor runs perfect once it starts, like I said above.

 

[flyingscott]

There is a passage between the carb bowl and primer assembly it just flows. Did you check the passage to the back side of the carb where it sprays out.

 

[b.gagnon]

If this motor is a 2-stroke you should never use starting fluid... You will ruin the motor.

 

[wolfee]

There is a passage between the carb bowl and primer assembly it just flows. Did you check the passage to the back side of the carb where it sprays out.

I saw the passage where the fuel just flows into the primer bowl but didn't notice another hole, I'll check it again in the morning. Is it at the back side of the primer bowl?

 

[wolfee]

If this motor is a 2-stroke you should never use starting fluid... You will ruin the motor.

I bought a squirt bottle and am using the oil/fuel mixture.

 

[flyingscott]

I saw the passage where the fuel just flows into the primer bowl but didn't notice another hole, I'll check it again in the morning. Is it at the back side of the primer bowl?

Yes there is another passage it goes to the back of the carb. When you push the primer it should spray fuel into the intake tract.

 

[wolfee]

No Title

Gonna try to upload a pic. It shows the bowl with the primer bowl behind it. The passage way into the primer bowl is completely blocked. The small hole above the passage way (at about 2 oclock) comes from the primer bowl and I am able to shoot carb cleaner through this pathway easily. The passage from the float bowl into the primer bowl is literally blocked (I think), I can't shoot carb cleaner through this passage but the blockage actually looks like the material making up the passage and I don't want to open this passage up until I get this verified that it should actually be cleared out. Thanks for your help!

 

[wolfee]

I've been trying to clean the passage(?) in the photo and I'm starting to wonder if it actually has a hole, I don't see one. Also, there's a 3rd hole (I think) at about 11 o'clock on the back of the primer bowl that looks like a second check ball is lodged in the opening. Is the hole blocked by the check ball the hole where fuel is supposed to shoot out when I prime, or is this normal?

 

[wolfee]

No Title

Here's what I'm seeing from the back. You can see what looks like a check ball in the small hole bottom left.

 

[flyingscott]

Don't touch that!!! The primer works like this. The fuel flows into the top part of the primer assembly through a check valve( that's why it looks plugged). When you push on the primer the fuel gets pushed past the lower check valve through the carb body. On the base of the carb are 3 holes the top one is for the idle mix screw. The big one is for the pump pulse, the lower small one is for the primer it will have a brass fitting in it MAKE SURE THAT ONE IS CLEAR

 

[wolfee]

Don't touch that!!! The primer works like this. The fuel flows into the top part of the primer assembly through a check valve( that's why it looks plugged). When you push on the primer the fuel gets pushed past the lower check valve through the carb body. On the base of the carb are 3 holes the top one is for the idle mix screw. The big one is for the pump pulse, the lower small one is for the primer it will have a brass fitting in it MAKE SURE THAT ONE IS CLEAR

Ok, the last picture I posted of the back of the primer bowl is normal (the one I said looks like a check ball is blocking the hole).
The first picture I posted shows two holes inside the bowl where the float sits, the small one is fine, the second one that looks like it's brass should have a hole, which I don't see. I can't imagine it's the size of the hole in the picture, it has to be more like the size of a needle?

 

[flyingscott]

You need to find a mechanic to help you. I am not there to do it for you. Maybe somebody else here can explain it better than I can.

 

[wolfee]

I can now see the bottom passage in the float bowl into the primer bowl actually is a check valve. I understand that when you press/prime, the bottom check ball opens up and allows gas to flow through the carb body. Now I just have to find the brass fitting you're talking about...just found it. The hole goes off at an angle toward the primer and it appeared to be blocked. I used a single wire from a wire brush to clean the hole out but it was only about 1 1/2 inches long. I connected the fuel line to the carb and still can't get anything out of the hole when I press the primer. I think I need a longer wire.