18xd died and won't start

[Lewis]

I've had pretty good luck with this motor until last weekend. I used it with no problems for five days in February, then winterized it. Took it out last weekend, and it started OK (a little harder than usual to begin with), and ran OK. Ran it at high speed, idle, stopped it and re-started a number of times for a couple of hours and everything seemed fine. Then while idling thru a fairly long no-wake zone it started to run rough and eventually died. I was never able to restart it. I tried taking the carb apart and blowing most of a can of carb cleaner thru it, and replacing the plugs. I know it is getting gas to the carb, and I know it is getting spark to both cylinders. I have a service manual and a Clymer's manual, but I'm not really sure where to start. Any sage advice? Not-so sage advice? Smart aleck remarks?
Thanks,
Lewis

 

[cell]

Re: 18xd died and won't start

Did you notice if it was peeing during the long no wake ride?

 

[Lewis]

Re: 18xd died and won't start

Yep, no problems with the impeller that I know of.

 

[jeridday]

Re: 18xd died and won't start

Have you checked for water in the fuel? How old is the fuel? Start by replacing the fuel and fuel lines if you haven't already. Maybe there is trash in the fuel filter. I had a similar issue with my 25xd. The old fuel line that was on mine was breaking down and clogging the fuel filter just enough to keep the fuel from flowing freely.

If you have spark to the plugs, it's likely that your problem has to do with the fuel.

 

[mark_gober]

Re: 18xd died and won't start

Lewis,

I have this exact motor. Have you tried putting the carb back on it and seeing if it'll start with either a shot of starter fluid or a little squirt of oil/gas mixture? That's what I'd try first. If it won't start, you can move toward spark. You say that it sparks, but how did you determine that? Since it died, have you removed the plugs to make sure that they are both sparking? One last thing would be to run a compression test. The two cylinders should both be around the same and somewhere in the neighborhood of 100psi. (this is simply been an observation, but you should check your service manual for exact specs)

Let me know if there is anything you want me to check on my motor for you.

Mark

 

[Lewis]

Re: 18xd died and won't start

Thanks, Mark and Jerriday.
I replaced all the fuel lines a year ago. They look good (most of the year the boat was under cover), and there is no sign of any sediment in the sight bowl or fuel filter.
I replaced the carb after cleaning it on the lake, and tried a few squirts of carb cleaner (didn't have starting fluid) in each cylinder. Still no go. Then I tried replacing the plugs and still no go.
I checked the spark by holding each plug (one at a time) a short distance from the block and seeing the spark. (Hint: if you are standing in water, you want the plug very close to the block!)
I haven't tested the compression, but the engine has been running fine, and I can't tell any difference now when pulling the starter -- not very scientific, but maybe rules out a dramatic drop in compression.
Lewis

 

[green4themoney]

Re: 18xd died and won't start

hmmmm. i had the same thing happen with my force last year it was idling then just made a ****ed kinda sound then started to run like **** then died... i blew a head gasket.... but im not sure (depending on what year your mercury is) if thats possible for you cause mercury simply used to just put a water jacket all the way around the top of the piston so the only entrance to the top is through the spark plug hole (eliminating the possibility of blowing a head gasket through your piston)

 

[Lewis]

Re: 18xd died and won't start

Thanks, Green. I'm pretty sure it's not a head gasket failure. Any other ideas?

 

[cell]

Re: 18xd died and won't start

Any sage advice? Not-so sage advice? Smart aleck remarks?
Thanks,

Well so far we have had sage,and not so sage.Time for a smart aleck remark.


You have a manual...get to work,and let us know what the problem was.

 

[Lewis]

Re: 18xd died and won't start

Well, I don't seem to be making much progress. As far as I can tell, the reed valves are fine. They look clean, they are closed tight, and they open easily with a soft push. As far as the carb goes, I took it apart, cleaned it very thoroughly, and rebuilt it with a rebuild kit. Everything seems OK, but the motor still doesn't start. When I pump the primer bulb on the gas line, gas shoots out of a hole at the top of the carb rather than going thru the carb into the engine. There's a hole in the main body of the carb sort of right behind where the gas line comes in, and that's where the gas shoots out. Any ideas?
Thanks,
Lewis

 

[green4themoney]

Re: 18xd died and won't start

can u take some photos for us?

 

[Lewis]

Re: 18xd died and won't start

I will get some photos posted in the morning. In the meantime, if anyone has a Mariner Mercury Service Manual (for 18-18XD-20-25-25XD-25 Marathon-25 SeaPro), you can see the hole where gas shoots out on page 3B-18. In the bottom photo on that page, it is the small hole in the body of the carb just behind where the gas line connects.