1980 50hp not running right (carb/cylinder problem) and starter problem

I have had some problems with this motor as I just bought it. I took apart the carbs and cleaned them as the bottom one was leaking fuel and the motor wouldn't start. I had also replaced all of the fuel lines because they were leaking fuel. The problem I'm having now is that the top two cylinders are not getting fuel. The motor starts instantly when I hit the ignition so I didn't think there was a problem until I took the top two spark plug wires off and it does the same. And then when I put them back on and take the bottom two off it doesn't start. Any ideas?

The other problem I have is with the electric starter. It works fine when I do not give it any throttle, but when I give around 1/2-full throttle the starter will run and then it drops down off of the fly wheel. Does anyone know what could cause this?

Thanks.

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

well you got some kind of fuel problem going on there for sure ....how were all the gaskets when you took it apart ? maybe you got some leaks there now ....I wouldn`t strip a carb unless I had all new seals and gaskets especially on a 32 year old motor......also the starter gear is deisigned to disengage from the flyheel gears when the motor starts and exceeds a certain speed.....is that what is happenning ...If you can get a service manual as it is your best source of knowledge .....good luck

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

You should first varify that the top plugs are firing good. The spark should be bright blue/white and able to jump a 7/16" air gap. If they are good then check that they are on the correct plug and not crossed. Then you will need to test the coils and other ing. componets. This is best do using a manual for the motor and meters. Manuals for the motor are a must have for working on a motor and is a cheap investment. Doing the formentioned test and get back to us . The SR# and modlue # will let us better help you with your trouble. JMO
oldman570

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

fisherguy123 said:

well you got some kind of fuel problem going on there for sure ....how were all the gaskets when you took it apart ? maybe you got some leaks there now ....I wouldn`t strip a carb unless I had all new seals and gaskets especially on a 32 year old motor......also the starter gear is deisigned to disengage from the flyheel gears when the motor starts and exceeds a certain speed.....is that what is happenning ...If you can get a service manual as it is your best source of knowledge .....good luck

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No it is not when the motor starts, it is when I was trying to start the motor (when I was having trouble starting it). Like it would take a while to start because of the leaks and stuff. The starter will run for ever with the throttle down but when its wide open, the starter will run for a second or two then go down. I can take a video if you want? I'm at college and my dad is working on the boat this week ( I could take a video next friday). He's going to replace all of the spark plugs and spark plug wires, although the spark plugs do arc from a good inch. He is going to do some stuff like rebuild the carbs I think. Maybe something to do to check the cylinders or something (I forgot what he said it was, not the compression.)

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

greendrake said:

No it is not when the motor starts, it is when I was trying to start the motor (when I was having trouble starting it). Like it would take a while to start because of the leaks and stuff. The starter will run for ever with the throttle down but when its wide open, the starter will run for a second or two then go down. QUOTE]
I just checked my service manual for my motor (82 merc 50hp) and it says to never exceed 30 seconds of cranking nand allow 3minutes to cool off in between or you will damage the starter...sounds like it may alredy be damaged to me. I wouldn`t fool toomuch with the motor unless I had a service manual.

Click to expand...

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

Bat poop! I hate it when I spell out a nice response, then hit the wrong button and zip, gone, not posted. Grrrrrrrrrrr

Nothing wrong with your starter, its working perfectly. The slightest release of pressure on the gear teeth from a cyl firing and the spring disengages the drive so as to prevent the teeth from grinding. It will not re-engage until the starter comes to a full stop then the instant acceleration of the shaft spinning causes the drive to 'screw' its way up the threaded shaft.

A factory service manual will be your greatest aide getting your carb linkage, idle adjustment, and ignition timing all synch'd to perform flawlessly.

Check this thread to see if yours is still available for free download.

Do you need any mercury manuals on pdf format!!! - Page 1 - 309079

Now, if I can just hit the correct button to post this and not lose at all, again! Somedays I should maybe stay in bed.

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

Don't feel bad Charlie as I have the same trouble myself. LOL If they were to make the keys bigger would help but then we would need a larger table for them to fit on.
Best of Boating.
Oldman570

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

You will not find your manual at the link indicated. As has been said many times, that link is only for later engines.

Here is the parts list for your engine:

Mercury Parts, 45/50 H.P.

The service manual for your engine is P/N: 90-86135--5

MERCURY MARINER OUTBOARD SERVICE MANUAL 45, 50, 60, 70 P/N 90-86135--5 | eBay

In the interim, here is the condensed version of the manual to help you:

Small Engine Repair Reference Center Home

Download this soonest to your computer as the link is short lived.

Gerry

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

Ok actually the problem is that all of the timing is off or something. My dad used a timing light on it and some cylinders were firing in two spots and some were all over the place. Any help on this?

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

It is VERY rare for a switchbox system to double fire a cyl, so the very first thing is to check every cyl.

Remove all spark plugs and turn the motor by hand, as each cyl comes to TDC mark a mark on the flywheel and number it. Now reinstall the plugs and start the motor. At an idle check timing one cyl at a time, each cyl's mark should appear in the same 'clock' position and in only that one position.

If any marks show in any other position write it down and repost.

Is this a distributor motor or the 2 switchbox and 6 individual coils? If switchboxes, check the White Bias wire that links the two boxes together, if there is a second white wire leading to another small black box, disconnect it, tape it off, and retest timing check on each cyl.

That 'third' black box is an idle stabilizer module which has been known to cause problems, most of us remove it and trash it to prevent future problems.

Edit: D'oh!,I thought (wrong) you said 150, you won't have two switchboxes.

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

The shaft of the starter needs to be cleaned with carb cleaner then lubed with a light oil (Olive ) something like that. It will disengage when any firing of the engine is taking over the thrust of the starter. Carb adjustment will help in correcting this. Choke the engine just until you hear it want to start then unchoke and turn over with a bit of high idle lever to get it going then back off. As for the intermintent spark check all wires for cracking and bare spots. if trigger or coil wire on cyl 1 jumps to cyl 2 when firing your ingnition will and can be firing on more than 1 cylinder due to arching. Try starting it at night and see if there is arching at the switchbox or plug wires.

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

150? I don't know what you are talking about..anyways I didn't think it had a distributor. My dad found a video on youtube and put numbers on the motor to help with the timing light. He put a number 1 on the 0 mark and a 2 opposite of that. Then a 3 and four on the other 'diretions' of the flywheel. So it would be like instead of NESW (north-east-south-west) it is 1 4 2 3 or 1 3 2 4. The 1 and 2 cylinders show the 1 and 2 numbers on the 1 spot and 2 spot. The 3 and 4 cylinders show at the 3 and 4 spot.


Here is the video and shows how he put the numbers on the flywheel. We have the same thing happening except it doesnt show 3 and 4 in the 1 and 2 spots.

And we did clean the starter parts. I don't know if that helped or not.

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

That video pretty much proves that the switchbox IS cross-firing.

If your motor is showing other numbers other than the cyl that the light is attached, then replace that switchbox.

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

A bad trigger can cause double or miss firing. I have only seen a few Merc swichboxes do this as it more prone to OMC ignitions

Re: 1980 50hp not running right (carb/cylinder problem) and starter problem

We have already replaced the trigger. I'll look into the switchbox.

And that is not our video if you think it is..i was just showing how we tested it.