Mercury Classic Fifty 1989 45 HP - In gear and stalls

[brstock]

I purchased a boat earlier in the year that has a 1989 classic fifty that I'm trying to get running. This is my first outboard so it is a learning experience so bear with me it I provide too much detail. I've gone over the motor top to bottom and done the following:

- Removed the carbs and cleaned every jet, port, etc. multiple times and reset the floats (doesn't mean I did them right). Replaced the gaskets and washers. Did NOT replace needles or remove any parts while cleaning other than the bowls.
-Pulled the lower unit and changed the water pump
-Changed the lower unit oil, no sign of water
-Checked the spark, all ok (did not check the voltage, just that there was spark)
-Checked the compression, 110 on all 4.
-Removed the oil injector
-I set the mix screws in the front to 1.5 turns out and it started with some coaxing but I ended up backing the screws out another 1.5 turns each and that allows it to idle and start up pretty easy. I can rev it and back it down to an idle without a problem. This is all in a barrel, not with muffs.
- I'm running 40:1 with mercury quick lean
- I replaced all the fuel lines and filter
- I rebuilt the fuel pump
- I have a new tank fuel line, bulb and motor end fitting
- I replaced the plugs

The problem I have is when I put it into gear. Most of the time it just bogs down and stalls. One time I was able to get it to run at an idle in gear for about 30 seconds but generally I had to take it back to neutral to prevent of from stalling. I have been able to get it to run in gear with the muffs so I seems to be the load of being in the water.

I noticed that the fuel filter is only about 1/3 full but seem to stay at that level, is that normal?

I pulled the plugs and they are all wet with some black residue after running

Any suggestions on getting her to run in gear?

Where are all the adjustments on the carbs? There are two to the upper right of the intake. Are there any other adjustment screws. I keep hearing about an idle set screw but can't identify it on the motor.

Background: This motor was sitting outside for a while. The person before me was having a problem getting it to high RPMs. When he would take it to the shop they would hook it right to a can and not have a problem running it. I found that one of the lines was too big for the fitting on the oil injector and leaking air so I took the injector out, not to mention that I saw many posts recommending the removal.

The carbs have the square intakes on the sides with 4 screws and the bowls are round except for an indent on one side.

There is a horse shoe shapped plastic piece on the top and when looking from the front of the motor the opening is on the right. Since idling is working I assume I have that right. I did not take it off when cleaning

I haven't checked anything on the ignition, mainly due to a lack of knowing how.

Any suggestions?

Thanks in advance!

 

[brstock]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

Fuel mix is 50:1, sorry it was late last night. Fuel is new. Black residue on plugs is in the fuel not encrusted to the plugs.

I saw the following post that goes through setting everything, does this apply to my motor? It says not for loopers but I don't know what that means.

http://forums.iboats.com/showthread.php?t=168855

 

[brstock]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

I have a feeling I have the carb in wrong. Shouldn't the throttle plates be moving open and closed as you move the throttle? Mine stay wide open except for when you use the choke......

 

[verado7]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

if you are refering the forward set of plates in the carb - yes they should stay open - they close when you choke it - thiose are choke plates - look deeper into the carb and you will see the throttle plates - as for the stalling - do you have a tachometer hooked up to it - you should to know how the motor is running at full throttle - the idle may be too low and or the carbs adjusted too lean .

to set up the carbs - hook the water muffs up - and while it's running turn the mixture screw on 1 carb at a time - to the right until it runs faster and then as it starts to slow -turn to right again until it runs faster -then as it slows come back an 1/8th turn - do the same to the other carb that will at least make sure it's set rich enough to start and run - you really need to get tach now and make sure it idles around 1050 - 1100 rpm on the muffs and with the tach you can check the max rpm on the water and that will decide wether you have the right pitch of prop for your boat and load so if you take 3 people with you normally have them with you when you check the max rpm she'll turn with that current prop - you want to at least hit 5500 rpm with this engine - it doesn't like anything much lower - i found these motors run best at 5700-5800 rpm stock with 10ml. of extra oil per litre - thats 2-300 rpm above spec. they are tough little motors but the 4cyl. was built for this .

 

[brstock]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

Thanks for the reply, I'll give this a shot tomorrow. Should it be in neutral or forward at an idle?

I pulled the needles all the way out tonight to see if they looked damaged and they don't. After putting them back in both slots on the needles now line up but they didn't before even after I seated them and backed them off. The bottom carb had a tight spot in the threads that obviously wasn't seated based on the position of the screw and I may have been stopping there thinking it was seated. Now that I have the front cover off I can get a closer look at the carbs (not through the holes in the front.) As an additional note these carbs don't have the fuel pump built in.

I have a tach but it hasn't worked since I got the boat. I'll look through the wiring and see if it is hooked up. I redid most of the wiring for accessories and if the same person did the wiring on the tach it would explain why it isn't working. Does anyone know which wire in the harnes is for the tach?

 

[verado7]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

adjust the carbs on the muffs in neutral - once she's running on the water you make the same adjustments but with the motor in gear so take a buddy with you -

 

[brstock]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

Ok, I have the tach working and I replace the float needles and springs and set the float level since that was the only thing I hadn't done to the carbs. Hooked her up to the hose and with a little choke she fired right up and went to about 2200 RPMs at idle so I shut her down and adjust the idle down to between 1000 and 1100. I started to turn in the top carb screw and it doesn't speed up like indicated in the post above, eventually it starts to bog down so I backed it to 1.5 and tried the bottom carb and it increased the RPMs so I backed it off the 1.5 and quit for the night.

When I took the carbs off one of the bowls was pretty much empty and there was fuel in the space above the inlet so I'm pretty sure that was my original problem. Of course if I had just replaced them when I replaced everything else I probably wouldn't be adjusting the carbs now Live and learn....everyone else learn from me and live better.

Should I start the adjustments with lower RPMs in idle so that I can hear the increase as I turn in the screw? Should I turn the screw in 1/8th at a time or keep turning non stop until it starts to increase the RPMs? If I should turn it without stopping how fast should I turn it? Speed of a second hand on a watch?

Thanks everyone!

 

[verado7]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

when your top carb didnt speed idle up did you turn the screw in opposite direction until it did / there will be a point when turning the screw either way a couple /few turns - that it will idle fast and then bog down - you want to to be turning the screw left til it revs up and just as it starts to come down leave it there - if it starts hard go a 1/4 turn more left .

 

[brstock]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

Thanks for the additional info. I'll try that later today but I'm getting all screwed up with the right and left I was able to get it on the water after setting the idle on the muffs at 1050 but as I would throttle up and start to plane out it would loose RPMs. I found that the fitting at the motor was defective and sucking air. I've fixed that (fitting at the motor.)

I had it on the water today and it would get up to about 4300rpms at WOT. This is with the screws at 1.5 turns (left) from seated. I was turning the needle to the right (clockwise) per your first post when it didn't increase idle. I will hook it up and give it another try and look for the higher RPMs. One thing I did find is that it was idling really high and the idle stop guide was not even touching the one on the carb so adjusting that isn't possible to lower the idle. I had to spin the fitting on the cable and adjust the bottom stop screw to get the idle down to the recommended level on the muffs. I'll give it another try, I was just happy to move via combustion instead of the trolling motor

 

[jasonmmoore]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

just joined, know nothing about computers, have a mercury 50 with a leaking fuel pump, will this cause it to suck air and not plane out

 

[Mi duckdown]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

Jason. start your own Q&A Don't piggy back. You will get more results. And yes to your Q.

 

[jasonmmoore]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

thanks. i dont know how to start a new anything cant find where to post new things , help??!!

 

[Mi duckdown]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

Jaon. Goto the top of this page Hit (F5) or refresh on the computer. On the upper left you should see Create a new post Click it. and Go for it

 

[brstock]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

This thing is driving me banannas. Took it out last week with the wife and kids and it turned around and started doing it again, loosing rpms as soon as the fuel in the filter runs out. I would watch the fuel flow down through the fuel pump and as soon as it ran out it would loose RPMs. So I decided to do two things, one replace all the hose clamps with better ones and two open up the fuel pump and make sure junk didn't get pushed in there. Just in case I ordered another fuel pump rebuild kit and while looking for the part number I noticed on the diagram it looked different from what I remembered when I rebuilt it. Sure enough when the kit came in it was different so I went ahead and rebuilt it again (this one had two holes in one of the diaphrams. In addition I found some posts online that recommend pumping the bulb with the directional arrow pointing up toward the sky to help the valves work properly. Other sites indicated that this should always be done and the bulb should be mounted in a way that it stays that way. So now everything is redone and I'll give it another try tomorrow. If that doen't work I'll send out the gps coordinates for the spot in the lake where I sunk it :O Just kidding, I'll get it eventually

Anyone have any input on the bulb orientation while squeezing?

 

[brstock]

Re: Mercury Classic Fifty 1989 45 HP - In gear and stalls

Found this post doing another search and thought I should post my resolution. Came down to the throttle assembly hitting the fuel line going into the bottom of the fuel pump. As the throttle moved forward it pushed on the fuel line and caused it to kink. I moved the fuel line to behind the bowl of the bottom carb and problem resolved. Hopefully this will help someone else.