'90 135hp V6 blackmax outboard - carb and reed valves

capslock118

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Hi,

This past spring I was told by one mechanic that my reed valves need to be replaced. Another mechanic told me this doesn't make any sense and that after a little tuning the engine was fine.

Engine worked great all season this year once it was in the water. At closing this year my engine was running 2.5k - 3k RPM at idle, on shore, and on ear muffs. I was running the engine to mix the sta-bil and to remove the fuel line and drain the carbs.

I'm not sure if the reed valves need to be replaced or if the carb needs to be cleaned. What I do know is that when the boat was in the water it was fine, but on land in spring and in fall it was running high at idle.

Next spring, I intend to learn how to tune the engine myself i.e. timing and adjusting the idle screw.

Is there anything I should be particularly looking for in the carbs or reed valves? I'm not a big fan of listening to my engine run at 2.5k - 3k while at idle on land.

Also, I was thinking about taking the carbs apart anyways to clean them and to learn all the different parts by hand instead of on paper. any tips?

also - i thought that it would make sense to do the reed valves and carb together if they need to be repaired since they appear to sit on top of each other.
 

Chris1956

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

Clearly your idle is too high. I would check the linkage for sticking, as that is a common cause.

Reed valves are fairly tough and reliable. You almost never need to replace them. I would look elsewhere.

BTW - clogged carbs do not make the engine idle high. Neither does bad reed valves. On the flusher, that motor should idle at 1000RPM or so.
 

j_martin

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

When the engine is in the water, it will get some backpressure on the exhaust and that will change the idle. Seems a little much, but some of what you're seeing is normal.

If it idles good in the water, the reed valves are good.

Check for air leaks in the intake or crankcase, including crank seals, a good carb ovehaul, link and sync, and I'd bet on a complete fix.

hope it helps
John
 

capslock118

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

Reed valves are fairly tough and reliable. You almost never need to replace them. I would look elsewhere.
If it idles good in the water, the reed valves are good.

Good enough for me, saves me money :). The only thing I should note is that the engine is from 1991. I don't know how many owners this boat dates back to but i do know the previous owner had it for 3 years and did not do any maintenance. :eek:

Check for air leaks in the intake or crankcase, including crank seals, a good carb ovehaul, link and sync, and I'd bet on a complete fix.

This leads me to more questions:
-how do i check for air leaks in the intake or crankcase and seals?
-i wanted to do a carb overhaul this coming spring / learning how
-by link and sync, this is synonymous to timing and sync? I plan on doing that / learning how to do that this spring.



another note:
I should have mentioned. When it was running on land, the RPM was fluctuating from 2.5-3k. It might have dropped to as low as 2k during the flucutations. It was generally stable but it definately flucuated.

Once the fuel started to deplete from the carbs the engine started to increase in RPMs, that's expected behavior though.

What would cause the fluctuation? That to me sounds like a dirty carb or something...
 

capslock118

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

One other thing:

What does the 'rebuild kit' for the carb include from mercury? It's about $93. Is that all i need for a carb 'rebuild' or does this mean something else?
 

Chris1956

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

Normally a carb kit will contain gaskets, inlet needle and seat, and maybe floats. It should be in the $20 range. You need three kits, for your three carbs.

An exploded parts list might show you what you ket for $93. Try crowleymarine.com for the parts list. Carb kits are likely widely avail aftermarket
 

capslock118

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

Let me make sure we are speaking about the same thing.

This is what I see for sale on iboats for the after-market 'Carb repair kit':
http://www.iboats.com/mall/partfinder/?*******=501706263&gd_grid_id=923&gd_poid=112208&gd_row=75&**********=134905022

Looking that up to the mercury equivilant, mercury calls that a 'Gasket set' for $10. Is this what you are referring to?

I'm having difficulties searching for what mercury calls a 'repair kit' and goes for $92 from them - however, from ebay it looks like it contains screws, springs, gaskets, washers...possibly needles?

[correction] found it. http://www.iboats.com/Carburetor-Kit-for-Mercury-1395-811691-2-Mallory/dm/view_id.710869?cm_mmc=Google+Shopping

looks like it includes needles, springs, gaskets etc.

For a full carb rebuild - I thought i'd be replacing the needles.
 

Chris1956

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

Normally the fuel mixture needles are not replaced. The gaskets, inlet needle and seat are routinely replaced. On some of those older Merc V6s the floats are NLA. Hopefully yours are in good shape, if that pertains to your motor.

I would recommend you find a kit (Merc, mallory, sierra) that contains inlet needle, seat and gaskets and go from there.
 

capslock118

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

Normally the fuel mixture needles are not replaced. The gaskets, inlet needle and seat are routinely replaced.

Ok then. I'll buy the kit you suggested, replace the routine stuff and check the needles, if they are bad ill replace them then.

What do you define as 'routinely replaced'? Once every 5 years? 1 year? 2?

On some of those older Merc V6s the floats are NLA. Hopefully yours are in good shape, if that pertains to your motor.

What does NLA stand for?

The engine dating from '90 I just assume it all needs help. But I'll take it one step at a time.
 

Chris1956

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

NLA is no longer available. Routinely means whenever you clean the carbs. If you let the motor sit with fuel in it for a year, then routinely is after that year. If you run the motor often and keep the fuel fresh, the carbs will stay clean a very long time(decade).
 

jerryjerry05

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

If you adjusted the timing.You sure it's set right?
Rebuilding the carbs is simple.Most cases they don't need to be rebuilt just cleaned.
What kind of floats do you have in the bowl? Foam/plastic? Ethanol is messing with lots of things.The foam ones are soaking up the fuel and making the carbs act weird.
You look at the fuel pump?Check the diaphram.
Do a link and sinc.Got the manual?
Idle in gear is about 750-800.
Out of the water it's gonna be about 1000rpm.J
 

capslock118

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

Got the manual?
Most certainly I have the service manual; worlds better than the seloc books. but I don't have a timing light and I've never done a link and sync. If you think that is something someone who doesn't know what he is doing can learn then great, I can maybe try; but I was thinking of just cleaning the carbs then sending it out to my local mercury shop to have them link and sync.

You look at the fuel pump?Check the diaphram.
I replaced the internal parts to the diaphragm last year when I installed a water/fuel separator so unless it had a short life span or I did something wrong I doubt this is a problem area.

What kind of floats do you have in the bowl? Foam/plastic?
Unless foam looks and feels like plastic now; I am certain these are plastic after tearing the carbs apart last night.



Routinely means whenever you clean the carbs. If you let the motor sit with fuel in it for a year, then routinely is after that year.

So this was a fun discovery. I took the carbs apart and the third carb (the one at the bottom) was just filled with fuel/oil mix. there was fuel/oil in the lines too.

I'm surprised by this, I thought that when you winterize an engine (i.e. run, pull fuel line out, let run till it dies) that action removes the fuel from the carbs. This is even the steps mercury recommends to close an engine. So is this a sign of a problem? problem of what?
 

CharlieB

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

After you ran out the fuel did you re-connect the fuel line?

On pontoon boats, I have often found carbs with substantial oil in them, over time the fuel had evaporated, leaving the oil, but the carb was kept full of fuel by the siphon effect of the fuel tank being higher than the carb(s). Those continuing evap made the oil concentration greater until eventually just pure oil in the carb.
 

capslock118

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

After you ran out the fuel did you re-connect the fuel line?
No, I leave the fuel line disconnected until spring.

Question about idle screws. I took mine off the carbs so that I could check how well they are doing. I was able to buy a rebuild kit that included the screws for about half.price on ebay.

I'm trying to figure out which screws match the ones I have; the kit came with two types.

I put mine in the center, the the fatter new one on the left and the thin new one on the right.

Which would you think would replace my screws? If we can't reach a consensus I'll just throw the ones I already have back into the carbs.

untitled%3E%20091.jpg

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untitled%3E%20092.jpg


My thoughts are the screw on the right is the closest match; however maybe they are so worn that they are actually suppose to look like the screw on the left?
 

CharlieB

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

Stay with the original screw.

It isn't the fuel that wears an idle mixture screw, it's the wanna-be mechanic screwing it in too tight and damaging the taper, forming a 'ring' arouind the tapered tip. This also deforms the 'seat' in the carb, together making idle mixture extremely difficult to adjust.

Where the service manual directs you to turn in the idle mixture screw to 'lightly seated' they mean exactly that! Very lightly seated, as if you used a fingernail to turn the screw, NOT even as hard as turning a screwdriver with two fingers.

This requires a delicate touch, NO heavy handidness allowed.
 

capslock118

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

Where the service manual directs you to turn in the idle mixture screw to 'lightly seated' they mean exactly that! Very lightly seated, as if you used a fingernail to turn the screw, NOT even as hard as turning a screwdriver with two fingers.

This requires a delicate touch, NO heavy handidness allowed.


Right, my engines service manual from mercury specifically states to set the screws 1-1/2 turn from seated; which I imagine is what you mena by lightly seated.
 

capslock118

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

another question:

the mercury service manual states to soak the carbs as well as all metal parts in carb cleaner fluid; wash off with water; air dry with compressed air.

for all other parts, rubber, platic etc. use solvent - same process.

what solvent would be best? naptha? i have acetone at home - that good?
 

CharlieB

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

Acetone may melt plastics!

Wal Mart Super Tech Carb cleaner in the spray can is one of the cheapest and best chemical I've found. It will also melt many screwdriver handles yet is safe for plastic floats.
 

aayjay

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

How did this job turn out, did you get er running? Did it cure the idle on muffs problem?
 

capslock118

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Re: '90 135hp V6 blackmax outboard - carb and reed valves

It turned out just great. I couldn't have done it without the mercury service manual; mercury outlines each step so precisely even a bozo like me can pretend he is a mechanic :p .

The only thing I could not do myself was the link and sync. I don't have a timing light or anyone at the time for a second hand. So after I did the carb cleaning and replaced all the fuel lines in the engine I took it in to my mechanic and had him do the timing.

Brought it back to the house, sounded good, runs perfect on the water. It was saying it was running somewhere around 1500 - 2000 at idle on land which the service manual said was ok.

The one issue I still have is this:
http://forums.iboats.com/showthread.php?t=488707&p=3302640#post3302640

though that problem has since gone away....for now..
 
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