Mercury 175 Full throttle problems

[Spindrifter]

The engine is a rebuilt 1992 175 2-stroke. The engine starts fine,idles fine, part throttle seems fine, but at full throttle it runs good for a few minutes then suddenly dies. It doesn't surge or sputter or anything, just dies suddenly. <br /> The pump ball stays hard the whole time and the motor restarts easy after it dies. Last time out it acted like I didn't have full power(hard to get on plane), when it did get on plane, it died again a moment later.<br /> I replaced the pump ball and fuel line and it still has the problem....any ideas?

 

[LubeDude]

Re: Mercury 175 Full throttle problems

I would bet it is an electrical problem somewhere since your bulb is staying firm, the next time you go out, take the cowling off and run it till it dies, then check the spark, Bet you have none. Whats wrong? Thats for someone else to tell you. I had a problem that wouldnt show up untill I ran the engine for over 20 minutes, had to take a tech out with me untill the coil failed, and he was able to find it then. Some problems cant be figured out in the shop.

 

[gss036]

Re: Mercury 175 Full throttle problems

Change your fuel/water seperator in case you have water. Usually you will have some surge with water but if it is almost full of water, could be running out og gas.

 

[Spindrifter]

Re: Mercury 175 Full throttle problems

The boat doesn't have a fuel/water separater on it, I was planning on adding one after I get this problem ironed out.<br /> Any other ideas guys? Help!

 

[gss036]

Re: Mercury 175 Full throttle problems

Are you running on an internal or portable tank? If internal, try different tank.<br />I am assuming you have a carbed engine, right? <br />I don't know much about the electrical system, so can't help you much there. Check for rubbed wires.

 

[KCLOST]

Re: Mercury 175 Full throttle problems

Check the spark at idle on the muffs....<br />This will at least give us some electrical answers. Adding the fuel/water seperater now may solve the problem also, or at least let you know if you have water in the tank(s).<br /><br />Use a spark gap tester $10... Let us know...

 

[bounder4465]

Re: Mercury 175 Full throttle problems

I had a 78 V-6 150 that did the same thing. Mine would not turn over 2,700 rpms, and would die at WOT. The 78 model had a two stage stator. One side for 0-2,500rpms, and the second side for 2,500+rpms. Dont know if your 92 has the same type stator..just a thought.

 

[Spindrifter]

Re: Mercury 175 Full throttle problems

I ran it with a portable tank this time with new plugs,fuel filter,fuel lines and pump bulb. Ran like a top to 4000....all looked good. I decide to push it to 5000 WOT. It ran for about 30 sec ,then a loss of power, then died. When I tried to start it, it acted like the motor was seized! It would click but not turn over. Finally it did turn over and started, minimal power and it sounded funny, so I shut it down....Hmmm. I let it cool down for a bit and tried it again, started fine and ran fine to 4000 rpm again. <br /> I compression checked it to make sure all was fine there. 110-115 on all cylinders. I looked into the plug holes to check for scoring. It looked ok as far as I could tell. The high speed stator kicks in at 2800 rpm so I don't think that's the problem. Maybe a lean condition or an oil problem causing it to seize?? Any input?