225 opti not running right

[Btuvi]

When first putting boat in water engine starts and runs out fine. Very shortly it begins to bog down. Put in neutral for a minute or two and it will run fine again. Then it will settle into 30mph range for a few minutes before bogging down to idle again. At that point when it does go again it will not run over 30mph without bogging down. And it keeps bogging down every few minutes before running up to 30 again.

I have now replaced plug and plug wires. I checked boat fuel water seperator and there is no water. I pulled off fuel filter and it feels very heavy but I haven't replaced it yet. Compression is ok.

As an aside: This is a seperate issue as the problems described above existed before this: I ran the resevoir out of oil and the engine container down to half full. 4 beeps. Added oil to resevoir. Now know that I need to run engine at idle with cap off of engine container. However, the thing I discovered is this: After running the resevoir out of oil I added 1 gal of Merc optimax oil. When the engine oil container didn't fill I removed it to check it and found that the oil was brown. Then I checked the oil in the resevoir and it was brownish. The oil I put in there was blue/green. The resevoir was dry when I put optimax oil in. Why is the oil brownish? There doesn't appear to be any water anyplace.

I thought about the possible connection of "not running right" to oil situation but the engine did run without beep and did use oil that was in resevoir and half of that which was in engine container.

What's my problem?

 

[JustJason]

Re: 225 opti not running right

the guy that owned it last may have but 10-30 in it... happens all the time.
The wally world 2 stroke oil comes all shades and colors as well.
You really need to run optimax oil in that engine.

You say compression is fine... and from your other post the numbers except for that one you couldn't test looked ok.

Take it to the shop.... you need special gauges to work on optimax engines.
My next question to you, is what are the fuel pressure and air pressure reading off of the rails.... but somehow i gather you don't have the optimax gauges.

 

[Btuvi]

Re: 225 opti not running right

Boat is at Merc shop and awaiting mechanics attention.

 

[Btuvi]

Re: 225 opti not running right

Merc mechanic said that diagnostic tools were out on other jobs so couldn't get much done. However, he did do compression and spark and said both were fine. Compression was between 90 and 100 all all cylinders.

Now here's the thing. When the first Merc dealer checked compression he came up with 100, 105, 115, 100, 115 and didn't check 6th hole because of stuck plug.

The only thing I can think of between compression checks that is different is that 6 0 ring gaskets were replaced on cylinder head and head cleaned. That does not seem enough change to explain the difference. What's going on?

 

[JustJason]

Re: 225 opti not running right

what's going on is that 2 different brand compression gauges will give you 2 different readings.

 

[Btuvi]

Re: 225 opti not running right

That's good to know but it sounds odd. One would think that a compression check is a compression check and that you wouldn't have to have several gauges sitting around and take your pick.

In effect (correct me if I'm wrong) you are saying that it doesn't really matter what the numbers are it only matters what they are in relation to each other.

Still - one check has the variation being less than 10 psi and the other as much as 15psi. What does that tell me? Pick the one I like best?

 

[JustJason]

Re: 225 opti not running right

let me know how you make out.

 

[204 Escape]

Re: 225 opti not running right

This may be way off, but could it be an impeller ??

 

[Btuvi]

Re: 225 opti not running right

Update:

When they first did a brief check on the engine I was told that plug wires were bad - not enough to be the whole problem but enough to be a part of the problem - they needed to be replaced.

However, when they got the plug wires in they found that they were a different kind that superceded the ones on there now. They did a search and found that there are no plug wire replacements for the ones I have and that the new ones require new coils. Not to worry though because the old plug wires are probably just fine.

They are telling me that the coil on #5 is bad - probably not the problem but needs to be replaced.

The oil pump and lines have been bled. Next step is to put it in water and put it under a load and vacuum out fuel line. I'm not sure what that entails but would like to know if someone can explain it to me.

I don't understand why replacement plug wires are not available. If the new ones that supercede the old ones require new coils then how difficult and how expensive is it to replace old coils so that new plug wires will work. I don't like the idea of using questionable plug wires. If they are questionable now won't they need to be replaced eventually and, if so, wouldn't it be better to do it now.

Any thoughts appreciated.

 

[Silvertip]

Re: 225 opti not running right

The reason you got two different compression readings is the same reason I have two blood pressure monitors. Neither one of them agree with each other and neither one agrees with the one the nurse uses and none of them agree with the one the doctor uses in his office. Compression gauges are a mechanical device and even if they were calibrated the same, the testing procedure, a change in engine temp due shop temperature and other factors can affect the readings. I'd be more concerned about the "stuck plug" than the compression readings at this point. Cross threaded no doubt by someone who shouldn't handle tools.

 

[Btuvi]

Re: 225 opti not running right

Latest

After determining that the new plug wires were not correct I contacted Mercury in Wisconsin. I spoke with a tech who assured me, despite my experience with plug wires being wrong, that they were the right ones. This is my third conversation with Merc techs and the third time that they have told me something that is not acccurate. The new plug wires do require that the coils be changed.

Merc dealer first told me that plug wires were bad. Then that they were not so bad that they needed to be changed. Then told me that they were bad and so removed the boot or cap on the wires and replaced them with new boots.

New coil to replace #5 came in and is installed. It came with plug wire attached. Plug wire is different than old wires.

Engine runs great now and I ran it yesterday for a couple of hours without failure - for the first time. Looks as if I got everything fixed just in time to winterize.

Thanks again to all of you for your help and input.