Need Help- cleaning carbs on Mercury 150

[Jason F-18]

So the Mercury 150 that is on our New-to-us boat ran fine the first couple of times taking it out. It was a little slow to get on plane, but I credit that to the big 14.75x23 prop that is on it right now.

Yesterday, taking it out is was hard to get started, and had a rough idle and would stall easily. Even once warm, if I shut it off for 5-20 min, it was very hard to get started again, had to give it a good bit of throttle. It also seems to be hesitating pretty bad when taking off. Once it gets above 3200 RPM, it seems to run real smooth. Still hit WOT of 5600 RPM running 56 Mph.

The boat had about 10 gal of fuel in it when bought, I ran most of it out, then refilled last week with Ethanol Free and added a can of B-12.
Is this a result of the B-12 in the fuel?

I am thinking the carbs may need to be cleaned out because the B-12 may have loosened junk in the tank, lines, bowl, etc. Does this sound possible?

I will also check the spark plugs while I'm at it.

That being said, does anyone know where to find a downloadable shop manual? I wasn't real comfortable with some of the sites I found that offered them.

Any help is appreciated!

 

[Gator]

Wrenchen2 will know the answer to these questions. If i were you I'd send him a pm.
If it was mine I'd first put in new plugs. I don't think the B-12 would do anything but help clean your carbs. I'm betting that old gas is part of the problem if not all of it.

 

[Jason F-18]

Thanks, have PM'd James

 

[STOUTBASSIN]

if it has been run with ethanol gas it can gum up the carbs. It is best to run non-ethanol gas

 

[SKIDROW37]

Mine did the same thing. My partner and I cleaned the carbs. It helped for a little bit but it wound up being the stator. It wasn't firing all the time.

 

[Jason F-18]

Ok, I pulled the plugs tonight to see what kind of condition they were in as well as the bore.

Below are the pics of the plugs in the following order: 2,4,6,3,5,7. They seemed to have oily residue on them, there was even a bit of oil sludge on the threads as well. Any thoughts?? What should I do next? I am going to get through this tank of treated fuel before doing anything else, then re-asess

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[wrechin2]

The sludge is probably from the plugs not being installed properly and fuel/oil coming out around the threads. Most common things that will cause a hesitation is carbs issues, stator (as mentioned), switch box, coil, fouled plugs, wrong octane fuel, wiring issue, trigger lead hard and sticking causing incorrect sync of the carb's to timing, or out of sync just to name a few. One real common issue is a fuel pump diaphram will rupture and flood 1 of the pulsating cylinders.

Here is a manual for a 92-00 135 to 225 mecury. 2.0L and 2.5L.


http://www.mediafire.com/?zznthjjywde

 

[Jason F-18]

Thanks for the responses guys. James, is that the order you would check things on it? The plugs did seem like they did not take much pressure to break free when I took them out.

 

[livewire]

That manual would be handy to have James do you have one for that 1980 115 inline mercury have.

 

[Jason F-18]

Thank you for the manual James. Reading through it and the ignition section, leads me to believe it may be the stator. It says that there are two packs for each side, a high side and low side. The low side controls spark below about 2700 rpm. So if it is not working correctly it would stand to reason that it would have reduced power wile accelerating, then when the high side kicks it, it would run normal. This is just what I feel. The motor hesitates until about 2500 - 3000 then the revs jump and it feels like you get kicked in the rear. I will check the spark to each cylinder tonight and also the voltage in the stator

 

[wrechin2]

Plugs are 20 FT LB or 3/4 of a turn when lightly seated on NEW plugs. You don't have the equipment to test the stator voltage. It requires a DVA or peak voltage adapter. I have plans somewhere to make one for about $15. Use a timing light to test it. It will tell you if volate is going through each plug wire but not the intensity. Usually a stator will cause a cylinder or cylinders to drop off. A timing light will indicate this. I would install new plugs and go from there.

 

[wrechin2]

livewire - 8/2/2011 12:31 PM That manual would be handy to have James do you have one for that 1980 115 inline mercury have.

</p>

Not a factory but I have made it active. It will help out in most cases and covers many engines. Read the instructions!!!!!!!!!!</p>

http://www.mediafire.com/?ezdtyzzwiotRead </p>

 

[Jason F-18]

Per the manual, I checked the spark gap using a spark gap tester set to about 1/4 in. Started the engine once connected and ran at idle. All cylinders showed good spark on them. I am going to try a new set of plugs and see how it does. After that the manual says to check timing before getting into stator or switch diagnosis. Am I on the right track?

 

[Jason F-18]

Put in new spark plugs. Ran it last night, definitely started and idles better, but still lagging on the holeshot. It still seems to need full throttle just to get up on plane and doesn't do well if trying to cruise at under 3000 RPM. Does this sound normal? Am going to run compression and leakage tests in the next day or two and will post numbers. Any ideas next?

 

[Jason F-18]

Just finished the leakage test, here are the results in cylinder order: 5%, 5%, 6%, 5%, 3% 3%.

The new plugs still looked good, but the one in #2 cyl seems to have more oil on it than I would imagine it should. The oil is still whatever the previous owner had in there. Should I try to drain this oil and try refilling with what I know to be quality oil? Could the wrong oil cause any of these issues?

What do you guys reccomend to use on a Carbed 150 Mercury? It has right at 325 hrs on it.

I'm thinking of running a can of Seafoam in it this week to see if maybe there is still some more carbon that needs to come out of it

 

[Gator]

Run the seafoam or B-12, according to directions, it should help.

 

[Jason F-18]

Thanks Gator, picked up a can of Seafoam last night. Will run it with about 10 gal of fuel. I have heard that when running Seafoam, it will cause the plugs to fould more easily. I still have the old plugs that I have cleaned up. Thinking about putting them in wile running the seafoam.

What has been your experience with it?

 

[wrechin2]

The leakage looks good. Was it done at TDC?

You may want to look at the trigger wiring. Sometimes the loom will get hard and cause a timing lag. Remove the throttle cable and work it by hand. Make sure the screw on top of the timing arm hits the block before it breaks away for the carbs.

 

[Jason F-18]

It was done at TDC.

Not sure I follow your explanation for checking the timing lever. I will try to give you a call later for more detail, thank you for all the help!

CFF is lucky to have someone like you who is so willing to share your knowledge for free! I can say that whenever my engine requires bigger work, you'll be the man I call

 

[Jason F-18]

So i think i have it figured out. One thing on the motor when we bought it was that there was no torque tab on the cavitation plate. Rather, it was a plate with a small hump like one used to be there. The guy we bought the boat from said it had always been like that. I didn;t think much about it becasue i can get the torque out by adjusting the trim. Well, I ordered one earlier this week becasue I figired it would make driving a little easier. It came in today and when i mounted it, I discovered that the prop hit it. Upon close inspection, I could see that the old one had been cut off and the whole thing painted black to look like it was made that way.

So it seems that someone put a larger diameter prop on it, I guess under the assumption they could get more speed. It seems the right pitch because I top out at 5600 RPM with about 7% slip.

It seems to me that having too large a diameter is causing it to bog down on take off. I really think the engine is running fine. The prop is a 14.75" prop, so I think I need to go down one size.

Does anyone have a 13.5" x 23P prop that I could try to see if it makes it better?

Am I on the right track?