Motor won't idle

[ellesar]

I let my son drive the boat and when he came off plane, he thought that it didn't matter when you goosed the throttle, you just had to goose it to keep it from swamping the back of the boat. So he goose it when the backwash was 10 feet behind the boat and then told me how good he did. As he was telling me this a tidal wave overtook the engine and killed it. I tried restarting it and could get it to idle just long enough to get it in gear and hit the gas. When we got back to the ramp ( 20 min and a good run later) I tried to get it to idle and it would just die. On the run bacxk to the ramp the motor didn't sound like it was running rough or anything but the speed and rpm's were down a bit. I was onlyt able to run about 60 mph instead of 67. I didn't try for long, I just wanted to see if anything seemed to be wrong other than the idle.

We had to hand load the boat since I couldn't get it to idle to get it on the trailer. When I got it home I put the muffs on and it still won't idle.

My thought is that one of the cylinders isn't firing. Does that sound like it could be my problem? Would swamping the engine like that cause a cylinder to stop firing? I checked in the cowl and nothing was wet. And looking at the air inlets at the top I don't know that it was enough water to actually get in the engine. But I can't just buy that it was a coincidence that right as that happened, the motor stopped idiling. The motor has about 20 hours on it so I'm going to have to take it in, but I was wondering what you all thought the problem might be and if there was something I Could check before the hour and a half trip to the dealer.

BTW its a Mercury 175hp Pro XS.


Thanks!

[EuropeanAM]

Start with the basics.... Compression, Spark and Fuel.

In your case- I'd start with a "spark test".

Also a good idea to carefully unplug the coils, injectors, and direct injectors (one at a time)... and ensure that there's no moisture trapped in the connectors.

[ellesar]

I've never done anything with a boat motor before, so what's the best way to test the spark?

Thanks!

[EuropeanAM]

First choice: A spark tester that has at least as many "connection positions" as you have plug wires.

Second Choice: A timing light, connected to one spark plug wire at a time, while the engine is running.

Caution- HIGH VOLTAGE!

[ellesar]

Thanks, I'll give that a try.


Do you think that the swamping of the engine could result in something like this happening? Could a little water getting in the engine cause this kind of trouble?

[EuropeanAM]

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by ellesar &raquo;</TD></TR><TR><TD CLASS="quote">Thanks, I'll give that a try.


Do you think that the swamping of the engine could result in something like this happening? Could a little water getting in the engine cause this kind of trouble?
</TD></TR></TABLE>

Definitely possible! BTW... don't forget to pull of each plug wire... dry out the ends (compressed air works well), and the reinstall.

[ellesar]

The mech said my problem is a busted compresssion fitting on the top of the motor. I have no idea what that is, but atleast its nothing major! Do you know what he is talking about and what might cause this to fail other than just "random failure'.

Thanks!

[EuropeanAM]

Perhaps a "COMPRESSOR fitting"... that would certainly cause some issues.