1976 Merc 850 kills when shifting into gear

[crestlinerdud]

I have a 1976 merc. 850 that is really turning into a project. First I had to replace most of the wiring. I put in a new switchbox as I was only getting spark in 2 cyl. I now have another problem. The motor kills when I put it into gear. I seems to shift violently. I took off the prop and tried it that way with no problem. I put the prop on and in the water and it does it. any ideas?

 

[Chris1956]

Re: 1976 Merc 850 kills when shifting into gear

Sounds like dirty carbs.

 

[crestlinerdud]

Re: 1976 Merc 850 kills when shifting into gear

I had to replace the prop as the spline insert was broke up from the violence of the shift. Its not that the motor simply dies its the violent nature of the shifting into gear that kills it.

 

[Chris1956]

Re: 1976 Merc 850 kills when shifting into gear

That motor should idle at 850 RPM or so. Shifting should not be violent. Still sounds like your dirty carbs are not allowing a slow enough idle, or your throttle cable is mis-adjusted, or the link and synch is off.

 

[crestlinerdud]

Re: 1976 Merc 850 kills when shifting into gear

any ideas as to where to start? I recently bought this motor and haven't had it on the water yet. I've too busy trying to get it in running shape. I don't have alot of experience but am mechanically inclined.

 

[Chris1956]

Re: 1976 Merc 850 kills when shifting into gear

Sure, Clean the carbs, set the floats properly and install new gaskets, new floats and new inlet needles and seats. now set the timing according to the link and synch procedure. Start and warm the motor on the flusher device and set idle rpm to 900 or less.

 

[Archer59]

Re: 1976 Merc 850 kills when shifting into gear

Sure, Clean the carbs, set the floats properly and install new gaskets, new floats and new inlet needles and seats. now set the timing according to the link and synch procedure. Start and warm the motor on the flusher device and set idle rpm to 900 or less.

That sounds like what you need to do. Once the motor idles in the flusher, be sure to set idle in gear on the water. I tie my boat up to the dock to set idle. Works great. Good luck with your project.

Nick

 

[crestlinerdud]

Just an update on this motor. I have lowered the rpms and cleaned the carbs. Took it to nearby lake and started it up. Everything sounded godd until I put it into gear. Then I had the same thing happen. I took it home and swapped out the lower unit and went back to the lake. I can now put it into gear but can only motor at low speed. It kills whenever I try to give it gas. I Think I need to do a complete carb job. I only sprayed cleaner and adjusted the floats so it would idle better. I also cleaned the fuel pump and replaced gaskets as they were in bad shape. Thanks for all your input...Karl

 

[Chris1956]

Karl, You might richen the idle mixtures a bit, to allow for acceleration.

 

[CharlieB]

Initial idle screws should be set to one and one-half turns out from very lightly seated. This should give enough fuel to get started, warmed up, and shifted into gear.

From there you need to adjust each carb to 'Best Idle Speed' while IN gear and IN the water. The load and back pressure must both be there or the idle mixture will be wrong.

Once at this 'Best Idle' then the motor needs even MORE idle fuel to provide the necessary fuel for crisp acceleration. Back each idle set screw out just twice the width of the screwdriver slot in the end of the needle. Test acceleration by rapidly opening the throttle to WOT, doing a holeshot. ANY bog, lean cough, miss, or hesitation is an indication the motor still needs more idle fuel. Back each out just another bladeslot width. Repeat acceleration test.

Repeat to perfection.

Note; A heavier loaded boat, like another guy, full icechest, etc. Increases load, idle mixture may need another bump richer when fully loaded for crisp acceleration.

 

[crestlinerdud]

So now I have another issue that needs to be addressed. I found out I'm only running on 3 cyl. I still have my old motor and took the wire for that cyl. off that motor and put on this motor. still no go. I even tried the wire from another cyl. and still no go. I'm hoping its not the switchbox. I took it to a friend who tested to see if there was current coming to the wiring block for the cyl. thats not sparking and he said there was. should I replace all the wires first or switchbox?

 

[CharlieB]

Swap coils to see if the no spark changes places. If not then most likely the switchbox is at fault.

HOWEVER due to that NO RETURN on electrical parts I seriously recommend you DVA test the triggers and the switchbox before spending any money on parts.

Get the FRE CDI Ignition Troubleshooting Guide. It explains most everything and clearly details how to test.

CDI Electronics Practical Outboard Ignition Troubleshooting

 

[crestlinerdud]

I have a place nearby that will the trigger and stator for me free of charge. Thanks for all your feedback. Been real helpful!

 

[crestlinerdud]

That will test the trigger and stator.

 

[crestlinerdud]

Just to give you all an update on the motor that refuses to cooperate. I tested the Stator and trigger with the Stator testing out ok and trigger tested ok also but it had some major corrotion of the wires. I installed a new trigger and still was running on 3 cyl. I had the switchbox from my old motor and I put that one in and got all 4 cyl. working.!!. Now I am working to set up the idle speeds. I took it out on the waret and got it to idle and keep running when I put it into gear. I can throttle up about half way and then it bogs down. should I back out the screws even more?

 

[Kitimat_DoubleEagle]

Yes keep turnin them out I ended up almost 2 and a bit turns out. I ran this boat all last summer went through lots if the same issues and this past weekend was the first time I went a whole weekend without taking the cowl off! You'll get there! One thing I will add I started using a . battery maintainer between trips. Seems to make a difference in ease of starting and running at idle.

 

[crestlinerdud]

UUGGHHH! still no go! 3 1/2 turns out at 1/4 turn adjustments and still bogging down.

 

[procraftguy]

Ok i read this whole post i had same issue with old motor it was a gas line from pump to carbs it was collapsed inside and only getting enough gas to idle took me 2 months too track it down so if any of ur gas line is old old id check them also compression test is first check when bogging down on 2 stroke asur motor will idle with 2-3 cylinders like a champ and fall on its face with a load or back pressure good luck

 

[Chris1956]

Once motor speed increases past 1200 RPM, idle mixture adjustment makes no difference. Since your motor runs faster than that, look for another problem in the carbs or spark advance or carb linkage.

 

[crestlinerdud]

Compression was real good at 140 - 145 on all cyls. will look into the carbs and spark advance and carb linkage this wk. thanks for the info. I will also look at my fuel lines in closely. all info really helps.