charging / lacks power in water 150 merc

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wrenchtrnr72

Petty Officer 3rd Class
Joined
Jun 5, 2004
Messages
78
Re: charging / lacks power in water 150 merc

i am still concerned about the output voltage to the battery it fluctuates too much (in my opinion) i am probably wrong< but just trying to give as much info as possible to help my problem.
 
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trumanlake

Petty Officer 2nd Class
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Aug 8, 2003
Messages
131
Re: charging / lacks power in water 150 merc

my money is on the stator. high speed windings are bad. that's my two cents.
 
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wrenchtrnr72

Petty Officer 3rd Class
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Jun 5, 2004
Messages
78
Re: charging / lacks power in water 150 merc

i have a funny feeling it is the stator, but not for sure. i just dont have the money to replace a bunch of parts, i just wish i had a dvm or another way to check this thang out. i am as broke as a steped on twig!! and might i say that is pretty darn broke.
 
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trumanlake

Petty Officer 2nd Class
Joined
Aug 8, 2003
Messages
131
Re: charging / lacks power in water 150 merc

somewhere i have the resistance readings for the low speed and high speed windings for the stator. i'll see if i can locate them.
 
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wrenchtrnr72

Petty Officer 3rd Class
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Re: charging / lacks power in water 150 merc

I would really apreciate that thank you :)
 
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wrenchtrnr72

Petty Officer 3rd Class
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Jun 5, 2004
Messages
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Re: charging / lacks power in water 150 merc

i thank yall for your help. now i just have to save some money and fix it.
 
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wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: charging / lacks power in water 150 merc

Have you tried actuating the choke intermitantly or squeezing the primer bulb when trying to plane? That would help to rule out fuel delivery as a problem. (How the motor runs on muffs doesn't tell a thing, since there's no backpressure or load). You might find a shop manual helpful in eliminating possible causes.
 
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wrenchtrnr72

Petty Officer 3rd Class
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Jun 5, 2004
Messages
78
Re: charging / lacks power in water 150 merc

that is a good idea! i will do that thursday. i just need to find a partner to pump the bulb because my arms aren't long enough? i will try it. thanks.
 
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AndyL

Petty Officer 1st Class
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Jul 1, 2002
Messages
307
Re: charging / lacks power in water 150 merc

It is probably obvious but have you checked the mechanical throttle linkage for proper travel, ie do the butterfly valves open fully with the stick down. I think you said you had the carbs cleaned and re-built so just a chance the linkage is not set up correctly. Check all 3 carbs operate in synch.It will ramp up to enormous rpm with no load and little throttle but a different story with load and water back pressure on the exhaust. You could also remove the airbox and check that the carbs are working correctly, you should see just vapour pouring through the throats not liquid. Be aware not to do this for long as it will cause thermal damage to the engine running without the air box.
 
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wrenchtrnr72

Petty Officer 3rd Class
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Jun 5, 2004
Messages
78
Re: charging / lacks power in water 150 merc

the throttle opens all the way. i am the one who rebuilt carbs and payed(i think) close attention to everything. i have a little bit of fuel dripping from carb throats, is this normal or no? '80 merc 150 xr2?
 
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AndyL

Petty Officer 1st Class
Joined
Jul 1, 2002
Messages
307
Re: charging / lacks power in water 150 merc

I am only guessing but if you have fuel dripping in the throats then I reckon either the float heights are set wrong or the float seats are not seating. This will lead to the engine flooding. Chances are the engine will idle as there is not enough venturi effect to pull in enough excessive fuel to cause a big problem , however once the airflow through the floats is high enough it will educt a significantly higher amount of fuel than the engine can handle and it will be totally over rich and cause the lack of power you describe. Obviously I cannot see your engine so am only guessing. I had a similar problem years ago with a merc 75. It would idle fine but under load it would give up the ghost. I removed the air cover and took it for a run in the "failed" condition and saw instantly neat fuel pouring through the throats which choked the motor. After replacing the needle seats she was fixed. Good luck and post any developments<br /><br />Andy
 
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delsol

Senior Chief Petty Officer
Joined
May 27, 2002
Messages
749
Re: charging / lacks power in water 150 merc

HOWS YOUR GAS, ITS NOT really old or been sitting, did you try seprate gas tank, had same problem with johnson , it was the carbs, but the voltage....i dont know, i think i am very handy and rebuild my 2 carbs , ran bad took to local dealer and he told me to never touch carbs again same problems you are having, he gave it back it ran like new, also how long have you had this problem, when was the last time it ran right
 
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wrenchtrnr72

Petty Officer 3rd Class
Joined
Jun 5, 2004
Messages
78
Re: charging / lacks power in water 150 merc

it has ran this way since i got the boat. its a good boat just some small things to fix. my fuel is new, new fuel lines and filter and primer bulb. removed 40 gal tank and cleaned. i am mixing 50:1 on 89 octane. '80 merc 150 xr2 runs and revs great dry, but in water my lawnmower out runs it.
 
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CU2NITE

Petty Officer 1st Class
Joined
Jul 9, 2003
Messages
226
Re: charging / lacks power in water 150 merc

Have you checked to make sure you have spark on all cylinders? Also look around the coils when the motor is running and see if a spark is arking across to the block. This can cause a runnability problem. If you don't have spark on all cylinders it may sound like its running good on land but under load it won't run worth a darn. Also if you have a cylinder down I would suspect a switchbox problem. Good luck and let us know.<br />CU<br /><br />---------------------<br />RUNNING THE MOTOR WHILE LISTENING TO THE HORN WILL MAKE YOU MORN!!
 
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Yarddog

Recruit
Joined
Apr 24, 2003
Messages
2
Re: charging / lacks power in water 150 merc

I had same type of problem last year with my 150 merc .Put it in gear ok but give it gas and it would die. Rode for over an hour at 1200 rpm's.Checked fire at plugs ,ran good on muffs.Took back to lake, cut off backing off trailer. Cut off a couple more times while accelerating and then took off like nothing was ever wrong.I think fuel sitting in bowels evaporateing leaving oiley residue clogged carbs(also happened on 50 hp johnson). I haven't had any trouble since using fuel treetment for extended storage year round,and disconecting fuel line to burn gas out of carbs.
 
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wrenchtrnr72

Petty Officer 3rd Class
Joined
Jun 5, 2004
Messages
78
Re: charging / lacks power in water 150 merc

i have carbs off and soaking, rebuild kits on order. this thang is a pain in the but.
 
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wrenchtrnr72

Petty Officer 3rd Class
Joined
Jun 5, 2004
Messages
78
Re: charging / lacks power in water 150 merc

that is the best news yet. thanks, i have a d.v.m. and a calculator!! appreciate the help!!!
 
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tkxus

Recruit
Joined
Jun 6, 2004
Messages
3
Re: charging / lacks power in water 150 merc

I am having the exact same problem as you are on a 1989 115 HP motor. Mine starts and runs great from 1800RPM down to idle; but it will not get over 2000 to 2500 RPM with WOT. I have read this entire post and am going to check my stator output.
 
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wrenchtrnr72

Petty Officer 3rd Class
Joined
Jun 5, 2004
Messages
78
Re: charging / lacks power in water 150 merc

on land mine runs perfect. but in water and under prop load it's a dog wont even get on plane, or even close to plane. it goes about 10 - 15 mph at tops, and this is a 150hp v-6?
 
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