Mercury HELP!!!!!!!!!!!!!!!!!

[skeet33]

I have a 84 150 mercury its been rebuilt 125 compression across the board its on 17 foot champion bass boat it takes along time to plane out i have a 23 pitch prop on it any suggestions to this once it gets on plane runs great rpms ar in the 5800 range full throttle.

 

[j_martin]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

I have a 84 150 mercury its been rebuilt 125 compression across the board its on 17 foot champion bass boat it takes along time to plane out i have a 23 pitch prop on it any suggestions to this once it gets on plane runs great rpms ar in the 5800 range full throttle.

Use a ventilated prop to let the engine spool up before it tries to plow up the lake with yer bote.

I run a 22 or 24 pitch high five on an XR4 (150) on an 18' tracker. (Nitro precursor) When I launch I tuck the engine in all the way and can it. It spools up to about 3 grand in a heartbeat, then jumps out of the hole like a frog. I'm on the trim as soon as I hit it.

Engine is set up on a 6 inch jack plate so that at about 80% trim the nose is up a bit, the engine is level, and the prop is about 20% emergent. More trim loses cooling. Top R's with a 24 pitch is 6000 at 63 mph. 22 pitch is for a heavy partner, skiing, etc.

Hope it helps.
John

 

[CharlieB]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

Is this a freshly rebuilt motor?

Are you running extra oil?

Has the timing been backed off a couple of degrees for the break in?

Is this a new problem or has the motor always run like this?

A compete link and synch following the manual ensuring carbs, timing, all set to spec may improve the hole shot, after the motor is fully tuned then check into ventilating your prop, but the first thing is make sure your tune up is to the letter perfect.

 

[skeet33]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

I got the boat with a blown up motor.Ive rebuilt it completely.Yes running extra oil for the break in period.ive replaced every electronic piece on it.One thing the fly wheel was separated so i dont know if the fly wheel is matched up right.ive followed the directions on timing it like the manual says.the boat and motor didnt come with a prop on it.I was giving a 25 pitch prop and it would never get on plain.Then i switched to the 23 pitch and now it gets up on plain just takes forever and if i wide open throttle it.It will bog down and die so i have to easy into it.I dont have a jack plate on the boat.the cavatation plate on the motor is lined up with the bottom of the boat.

 

[j_martin]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

I got the boat with a blown up motor.Ive rebuilt it completely.Yes running extra oil for the break in period.ive replaced every electronic piece on it.One thing the fly wheel was separated so i dont know if the fly wheel is matched up right.ive followed the directions on timing it like the manual says.the boat and motor didnt come with a prop on it.I was giving a 25 pitch prop and it would never get on plain.Then i switched to the 23 pitch and now it gets up on plain just takes forever and if i wide open throttle it.It will bog down and die so i have to easy into it.I dont have a jack plate on the boat.the cavatation plate on the motor is lined up with the bottom of the boat.

1. It'll run a tad lean with extra oil. Might make it a bit touchy on the hole shot.

2. Flywheel shouldn't make any difference. Timing magnets are on the hub. If in doubt, don't hurt to turn it one bolt either way.

3. Does it have an advance or idle stabilizer module on it. If so, try disconnecting it and set your WOT timing to 23 degrees BTDC.

4. If it seems weak till about 3000 rpm, then takes off, it would be worth while to check stator (charge coil) voltages at the switchboxes. Might be a weak low speed stator coil.

5. A ventilated prop helps a great deal with a work boat, like a bass boat. It lets a little exhaust gas spoil the grip till you get moving, then the water flow over the prop shuts off the ventilation. Usually we run a stainless prop on a V6 engine. They're both stronger and more efficient.

6. If you didn't go through the carbs at rebuild time, I'd re-visit that task. Something blew it up the first time. Carburetion is the usual culprit after loss of cooling.

hope it helps
John

 

[skeet33]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

yes it has a idle stabilizer module.heres were i get confused on the timing.the book says to time it by cranking the engine at regular cranking speed,or do i time it while its running.ive checked and rechecked my voltages at stator coil and switch boxes ive pulled my hair out so ive put the boat up for the winter now fishing season is fixing to start so im trying to get it right.theres not a marine shop close by here to take it to ive been a automotive tech for 10 years now so i dont think it would be this hard to figure out.the carbs were nasty very clogged up ive soaked them in carbcleaner for a few days blew them out ive done that several times.i found out from previous owner that he had forgot to change the waterpump when it went out on the lake he drove it back till it locked up.what a waste.But she fires up first key stroke idles smothly just when in water under a load does it act up.ill go back and check everything once again i just might have my timing still off not real clear on it.Thanks for all the info.

 

[CharlieB]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

WOT timing can be set cranking with the plugs out and the wires grounded or attached to a spark tester.

If our carbs have adjustable idle mixture, set idle mix to BEST idle IN GEAR while on the water PLUS almost an eighth turn richer, to provide adequate fuel for acceleration. Too lean and the engine bogs and dies, slightly lean it is still a bit slow on acceleration.

Once idle mixture is perfected then adjust idle speed with idle timing adjustment screw.

The link and synch and idle mixture are critical.

 

[Dukedog]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

Has tha gearcase been changed? Gear ratio makes a BIG difference with tha little 2.0 motor on a heavy boat...............Its just one of tha little things that can add up.

Should have tha WH carburators which are tha easiest things ta clean and adjust (theres not any other than floats which need ta be right). Tha only way ta change 'em is with tha jets..........

 

[skeet33]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

as far as i know its the original gear case.yes the carbs are the wh ones very easy but the only thing to adjust is the floats ive rebuilt them with all new parts.so as far as idle mixture im guessing they do it on there own.i know the 2.o is little moror should i go with a smaller pitch prop right now ive got a 23 pitch when i got the boat it didnt have one on it.Thanks for the info

 

[j_martin]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

If the idle stabilizer is also an advance module, your WOT timing spec is probably 19 degrees BTDC. The advance module then advances the timing at about 5000 rpm to 23 degrees. Probably retards it to 17 degrees at 5500.

Without the timing, you set the initial WOT timing to 23 degrees.

All timing adjustments are made at cranking speed.

Provided you're prop pitch is not too high, the increased advance should give it pretty good kick out of the hole.

Again, on that engine and that boat, I would think a ventilated prop is very important for the hole shot.

hope it helps
John

 

[skeet33]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

I think i may have it when i set the timing i set it up at tdc ive got a dial indicator now so im going to set it up at top dct then back off to .462 then set my timing off that mark i just might have it to much off that when i do get into it the timing isint advancing like it should im going to give that a try this timing thing is diffferent than a car.thanks for the help i let you know what happens after i redo it.

 

[skeet33]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

my timing is at 23 degrees coils are in spec stator checks out good trigger checks out good carbs have been gone through 4 times now.ive done away with the male and female fuel conector.runnin a 23 pitch prop everything on this motor is new.you trim it all the way down gas it good and it dies everytime.you easy in to it slowly you can get up on plain and it runs great once on top of water.i get 5200 rpms out of it at wot.ive totally give up taking to a boat shop now.ive been a automotive tech for 12 years now and this one got me all up tight

 

[CharlieB]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

Classic symptoms of a too lean idle mixture.

You're used to cars, adjusting idle to best idle. That's not quite like a 2 stroke.

The 2 stroke does not have an accelerator pump, so the idle MUST BE RICHER to provide the additional fuel for acceleration.

While ON-THE-WATER and in FORWARD GEAR, adjust the idle mixture to best idle speed PLUS almost another 1/8 turn out.

Test by slamming the throttle control to WOT, ANY hesitation, bog, or lean cough, fatten the mixture just another width of the screwdriver slot.

Repeat acceleration test, adjust to perfection.

On the hose you may have to turn out about 1/4 turn, but on the water is the most accurate method.

Edit:

Running an oil rich mixture on a fresh motor, the idle adjustment should be done again once the motor is broken-in and the oil mixture is returned to normal 50:1

 

[skeet33]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

these carbs dont have a idle mixture screw on them.theres is three carbs and there just jets and fuel bowls no adjustment screws to them they been cleaned out 4 times now.all passages have been blown out with air.i took to the local marine shop today they goin to put it up on the dyno and see what the problem is.

 

[CharlieB]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

Float level is critical, too low and the idle runs lean.

Oil mix also makes a difference. A 'double mix' on a fresh motor is actually LEAN as the additional oil displaces fuel, which makes the motor run LEAN, which is the reason the OEM Break-in procedure clearly states NO WOT throttle for anything more than the few seconds to get on plane, and that is allowed only after the first full tank of fuel is used.

You can fatten the mixture by raising the fuel level (lowering the floats with the carb inverted) as little as a 1/16 inch can make a noticeable difference.

 

[skeet33]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

Ok ive taken to boat shop.they found that my fuel pump diagpram was over stretched they replaced it boat runs great.Now with that said im running a 23 pitch temptist prop on the motor with me in the boat it gets up and goes i can get up over 6000 rpms out of it but i keep it around 5600 rpms.With all that said my brother and i went out to the lake this past week and it wont get out of the hole he had to go to the bow before it would get up on pad.Get him out the boat with just me its fine.Now with both of us in the boat once its on pad i can get 6000 6200 rpms out of it but i dont stay there long.this is a 84 model champion bass boat with a mercury 2.0 liter didnt come with a prop i found this temptist question is what prop should i be running on this boat.THANKS

 

[Coloradolakeboy]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

I've got a 18 ft Glastron bass boat with a 2.0 L. It had a SS 21" on it until I moved it to 5000 ft. Now it has a 19" if that's any help.

 

[will941s]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

Keep that 23 pitch on there for yourself, borrow a 21 pitch and try it with your brother, keep going down pitches until it will handle 2 or three people without a problem. Also, make sure you have the weight evened out in the boat. Need some up front...maybe a battery, a couple of anchors...could make a HUGE difference in performance.

 

[scorepts]

Re: Mercury HELP!!!!!!!!!!!!!!!!!

this thread seems to have died 8 months ago but im new here ind i wanted to add my two cents. i have a '84 ranger 370v 18' with a 150xr2. when i bought the boat i thought the 21 pitch on the prop was odd but its what the boat came with. that being said when i hit the throttle with me and a buddy in the boat and all our gear it jumps up on plane in about 2 1/2 seconds litterally, and runs 58mph @5600 rpm. i would have to say that your pitch is wrong. higher pitch is good for top end but bad for getting there. my buddy has a '02 nitro with a 135 merc and one of us usually has to jump upfront until it begins to plane out but his top speed is the same as mine. he runs a 23 pitch prop. hope this helps you or anyone else reading this thread