[capnrobalo]

My motor is losing power when I come down hard off waves. I can be running at 4000 rpms and when I land rough, the rpms will drop way down and I lose power and then they may or may not go back up. Sometimes the engine stalls completely. Almost always, after a stall, I am immediately able to start the motor back up with no problem. But, I have a loss of power for a little while. Prior to this weekend's trip, my mechanic rebuilt all three carburetors, rebuilt the fuel pump, and fuel filter. I also replaced the fuel/water separator before the trip. The motor ran fine (in rough seas) for about 40 miles or so and on the way back in it started acting up. The problem has never shown up when I run in the local lake. I had to be towed in two trips ago (before the rebuilds) because I finally couldn't start the motor back after it cut out (I was unable to prime the bulb). That trip prompted me to have the mechanic look at it and they diagnosed it as gunk in the carburetors causing the needle and seat to stick. But after their repairs the problem remains. Any suggestions for what to look for next? Thanks for any help.

[gss036]

Pull the "new" fuel filter and drain it into a clear container so see if you picked up water. If you have a lot of water in the filter, chances are pretty good that you water in you main tank. If no water, the look inside the fuel tank to see if you have something that is blocking your pick up tube. It could be mechanical but sure sounds like water getting mixed up in the gas. Especially since it never happens on the flat and calm. I have read posts where some boats were getting water in through the tank vent holes. If that is the case you might have tp put a goose neck in the vent line to keep water from entering.

[capnrobalo]

Thanks for your help. Without tearing the deck off, I don't think I can get to the tank to look at the pickup. It's a 100 gallon tank and mounted below the deck somewhere. If it was water in the fuel, wouldn't it happen all the time once the water made it to the carbs? It only really happens immediately when I pound the water after riding over a big wave. For that reason, it seems mechanical to me but I don't know the inner workings of the fuel pump, etc. I've read some other posts with similar problems where the culprit was an air leak in the fuel line or even a bad primer bulb. Does anyone think the symptoms I get could be related to these?

[heybaylor]

Once had a "ball" of congealed gasoline floating in a tank...similar symtoms..i/e when on high rpm all the sudden power loss..sometimes die . then "gunkball" floated away from pickup ..would restart..and run ok ..until again at high rpm the "gunk ball would get to the fuel pickup in the tank.was very large , when dumped out of tank, was as big as a volleyball..boat had sat one time for about a year with gas in tank..just something to think about /check

[gss036]

I would not go to that much trouble to check the tank pick-up unless you are at last resort. Usually there is an access panel to get top fuel wires and lines. The fuel pump is a diaphram type, so I don't think that would have any effect of bouncing. It is possible the floats in the carbs are set wrong, they might have a tendancy to bounce around if you beat the boat hard enough. A friends I/O floats stuck on us one day in 3-4 chop and gave us a scare. Water should not be getting into the carbs w/seperator, but could easily fill up the filter enough to cause problems and then when the gas settles back down and floats on top of the water, the filter allows it through enough to run. In about 3 ft chop you may get some surging until it is clead out. That is the great thing about having a Racor, you car drain quickly, so you know there is no water.I just can't think of anything mechanical that bouncing around hard would have any effect unless you have a bad/loose ground wire somewhere. Wish I could be of more help, but I am not a mechanic, just writting from experience w/my 1989 200 merc.

[heybaylor]

if its a problem acessing the tank ..then run a portable tank ..see if indeed your problem is in the tank.very easy to do ..

[capnrobalo]

[capnrobalo]

Originally posted by gss036: I would not go to that much trouble to check the tank pick-up unless you are at last resort. Usually there is an access panel to get top fuel wires and lines. The fuel pump is a diaphram type, so I don't think that would have any effect of bouncing. It is possible the floats in the carbs are set wrong, they might have a tendancy to bounce around if you beat the boat hard enough. A friends I/O floats stuck on us one day in 3-4 chop and gave us a scare. Water should not be getting into the carbs w/seperator, but could easily fill up the filter enough to cause problems and then when the gas settles back down and floats on top of the water, the filter allows it through enough to run. In about 3 ft chop you may get some surging until it is clead out. That is the great thing about having a Racor, you car drain quickly, so you know there is no water.I just can't think of anything mechanical that bouncing around hard would have any effect unless you have a bad/loose ground wire somewhere. Wish I could be of more help, but I am not a mechanic, just writting from experience w/my 1989 200 merc.

I spoke to the mechanic today and he mentioned that there may be some trash or something causing the needle(s) to stick. I don't exactly know what this means because I don't have the carburetor handy. When they rebuilt the carburetors a couple months ago, they adjusted the float levels, etc. so I think those *should* be ok. Does anyone have an exploded view available on the web of a typical Mercury carburetor/fuel system? My boat is in storage an hour away from me so it's not so easy for me to tinker with. Thanks for the help.

[capnrobalo]

Originally posted by heybaylor: if its a problem acessing the tank ..then run a portable tank ..see if indeed your problem is in the tank.very easy to do ..

I have considered this and the next time I go offshore I will probably take a spare fuel cell with me. Unfortunately, (fortunately?), the problem I have does not show up all the time so it's hard to know when I leave the ramp whether or not I'm gonna see it. And then again it only has ever happened in rougher water than I can find within 300 miles of here so I can't easily run tests myself. Also, the mechanic has no way of simulating the jarring I get when I am offshore ... grrrr

[gss036]

http://www.biggerhammer.net/mercury/factory_manuals/ http://www.mercurypartsexpress.com/P...e/homepage.asp Either one of these will get you to exploded views to give you an idea of what the inside looks like. Carbs are not that complicated, if you have a little mechanical skill you can rebuils one.\ If they rebuilt your carbs correctly and you have changed the filters, there should not be anything in your carbs. Try running on a small tank with a very strong mixture of SeaFoam or Chevron Techron fuel injector cleaner, both are very good products, maybe they will disolve anything in the carbs, which really shouldn't be there after a rebuild.I was hoping some of the good mechanics would jump in a share some ideas on this also, maybe they are stumped also.

[capnrobalo]

Thanks for the links and info!

Originally posted by gss036: http://www.biggerhammer.net/mercury/factory_manuals/ http://www.mercurypartsexpress.com/P...e/homepage.asp Either one of these will get you to exploded views to give you an idea of what the inside looks like. Carbs are not that complicated, if you have a little mechanical skill you can rebuils one.\ If they rebuilt your carbs correctly and you have changed the filters, there should not be anything in your carbs. Try running on a small tank with a very strong mixture of SeaFoam or Chevron Techron fuel injector cleaner, both are very good products, maybe they will disolve anything in the carbs, which really shouldn't be there after a rebuild.I was hoping some of the good mechanics would jump in a share some ideas on this also, maybe they are stumped also.