Merc 25xd won't stay running

[humdogj]

Hello all! Newbie here. I don't know much about boats but my dad's Mercury 25xd won't stay running. This spring he had it fired up before putting it in the water. He said it ran fine and then when he put it in the water, it wouldn't even start. He put fresh gas in it.

A friend and I looked at it and I'm no expert, but here are the things we tried.

The primer bulb primes and feels hard. The line into the fuel filter is filled with gas and I took off the line from the fuel filter to the carba and gas comes out. I took off the fuel line into the carburetor, squeezed the primer bulb, and gas comes through the whole system. There doesn't seem to be any leaks in the line because the bulb is rather tight, and all lines feel hard.

We sprayed carb cleaner into the carb, I manually operated the throttle from the engine, and it started, but died after a few seconds. I connected the lines back up and tried it again, but nothing. Put some gas into the carb and it started, ran a few seconds, and then died. It would only run for a few seconds whenever we put gas or carb cleaner straight into the carb.

What could be causing this. Is it the float, needle, etc, gumming up that could be causing this...like I said, I'm a newb and don't know too much. To me it seems like there isn't getting gas into the carb to keep it running. Any advice would be greatly appreciated. Are there things I can try to "unstick" parts? Will I need to pull the carb (I have no clue how that's done)?

The boat is up north and I'm nowhere near it so I don't know what year it is. Thanks.

 

[will941s]

Re: Merc 25xd won't stay running

As far as the year model, as long as it's past about 1984 it really doesnt matter except for a few parts. Sounds to me like you need to rebuild the carb. Which is the cause of about 98% of problems with these motors. The carb has a integrated fuel pump and priming system....so everything in the carb always needs to be squeeky clean for the motor to run properly. Get a rebuild kit, remove the carb, take it apart and clean it with carb cleaner and compressed air. All passages, holes, everything inside needs to be clean. VERY EASY JOB. For now, when you take it apart, don't remove the idle set screw, adjust or anything. The kit will come with gaskets for all variants of the carb through the years so there will be gaskets left over. Also, get a water fuel separator, it will allow that carb to stay cleaner, longer and avoid alot of annoying problems that come from the ethanol fuel. Let us know how this turns out.

 

[verado7]

Re: Merc 25xd won't stay running

yep if you can get it running by spraying fuel in the carbs - rebuild the carbs .

 

[humdogj]

Re: Merc 25xd won't stay running

Alright, I just got back from vacation and I will look into getting a rebuild carb kit. Then, hopefully over the next few weeks I can get to my dad's and get this thing figured out. Any suggestions as to where I should get the rebuild kit? Thanks.

 

[will941s]

Re: Merc 25xd won't stay running

RIGHT HERE ON THE ONE AND ONLY IBOATS!.....it's where I buy mine, and cheaper then the "other" guy

 

[humdogj]

Re: Merc 25xd won't stay running

Thanks for your replies. I was trying to figure out which carb rebuild kit to get and I am running into some problems. The SN for the motor is 6500614, Mercury 25XD. When I search for the carb part I get a few different options like WMC 26/27, WMC 11/12. The problem is that on the carb that my dad has it has WMC 31-84. Without pulling the carb and taking it in to get it matched up, because I'm not up north right now, is there a way to figure what parts kit I need? I called a service place around here just to see if I was missing something but I've had more luck with your replies!

I'm not sure if someone else has put a carb on through the years that didn't match up with the numbers. Any help is greatly appreciated. This will be my first carb rebuild (going to have a buddy help that knows what he's doing) so I really look forward to this. My buddy is out of town so I'm trying to prep everything beforehand.

 

[will941s]

Re: Merc 25xd won't stay running

Does it have a square primer offset on the side of the carb?

 

[humdogj]

Re: Merc 25xd won't stay running

Jeeps, I have no clue from trying to remember what it looks like. I did find this image of what mine looks like (from the best of my knowledge). I'm not sure if it's exact because the boats not by me and I know the models are different. Is this what your talking about or would it be on the other side?

I found the pic from user mcgheeboathouse.

I'm going to try and get up there this weekend to get the boat out of the water and try and get the carburetor off. From last look, it seemed like it might be trouble getting it off considering I think there are a few things in front of it. One of the screws that hold the carb to the engine block looks easily accessible, but the one on the right looks like of buried. What things will I have to remove to get at the carburetor?

Lastly, I was wondering if the choke (I think that's what it is) should be pushed all the way in, or pulled out while running? (2nd picture, bottom red arrow. Once again, I found this pic somewhere on these forums.)

 

[Merc4Life]

Re: Merc 25xd won't stay running

choke should be open after motor is warm

 

[will941s]

Re: Merc 25xd won't stay running

Choke knob all the way out once, shoots fuel into carb (primer), Back in 1 click-full choke, 2 clicks-half choke, all the way in-running position. Pull it out the prime the carb, then back in 1 click or 2 clicks to either full choke it (cold weather) or half choke it (warm weather), then once it warms up push the choke knob all the way in to run. And that is the newer style carb. 1983-present carb kit will work

 

[humdogj]

Re: Merc 25xd won't stay running

Just got back from up north and I successfully got the carb pulled, cleaned, and put back in. The pontoon started right back up. The needle was stuck in the seat, so I pulled it, sprayed it and the hole down with carb cleaner, and then put everything back together. I didn't need to replace any parts. It fired right up and ran well.

It was an easier job than I thought it was going to be. Thanks for everyone's information on here. I really appreciated it.