1980 25 hp mercury outboard won't start

[xman33]

I have a short shaft 1980 25 hp merc outboard that won't start but will only starts with starting fluid. When running with starting fluid, It will run if I give it gas and dies out if I put it on neutral. I rebuild my carb,clean as best i could even boiling it and replacing it with new gasket and a fuel pump kit. I also set and check my spark plugs and float heights placing them at mercury specs. My sparks are orange and bright light blue. Gas is getting in the carb I think. The pump gets hard when I pump it and I can see gas traveling to my fuel filter. I also dump out the old gas and replace it with new gas but to no avail, it just won't turn over. It sounds like its almost gonna fire up but there's something that's preventing it. I think i could flood my engine if I want it to. Am I getting too weak of a spark ? Do I need a stator or new coils? I'm new to outboard and this is only my second motor I've own so I need help guys. Any ideas would be much appreciated. I'm at wits end. Thanks for looking and have a nice day

 

[CharlieB]

Re: 1980 25 hp mercury outboard won't start

Starting fluid is a big No No with a two stroke as it does not have any oil to lubricate the crank and pistons.

A better solution is a bit of pre-mixed fuel in a squirt bottle.

Now, the fact that the motor does start and run with the throttle open tells us that the ignition system IS working, and your problem is still in the carb.

The idle circuits of the carb are very small, boiling it out will not clean those small passages. Often even soaking in carb cleaner will not get all the crud out.

A good spray solvent followed by compressed air is far more effective at clearing small passages.

Wally World Super Tech carb cleaner is under 2 bucks a can and is one of the best solvents I've found. Use the little tube pressed against each hole in the carb and spray thru watching carefully to see that the solvent comes out the hole inside the carb throat.

WARNING: WEAR GOGGLES or a FACE-SHIELD. This solvent is VERY PAINFULL and damaging to your eyes.

Blow compressed air thru to ensure all crud is removed.

Reinstall and adjust as spelled out in the service manual.

 

[xman33]

Re: 1980 25 hp mercury outboard won't start

Starting fluid is a big No No with a two stroke as it does not have any oil to lubricate the crank and pistons.

A better solution is a bit of pre-mixed fuel in a squirt bottle.

Now, the fact that the motor does start and run with the throttle open tells us that the ignition system IS working, and your problem is still in the carb.

The idle circuits of the carb are very small, boiling it out will not clean those small passages. Often even soaking in carb cleaner will not get all the crud out.

A good spray solvent followed by compressed air is far more effective at clearing small passages.

Wally World Super Tech carb cleaner is under 2 bucks a can and is one of the best solvents I've found. Use the little tube pressed against each hole in the carb and spray thru watching carefully to see that the solvent comes out the hole inside the carb throat.

WARNING: WEAR GOGGLES or a FACE-SHIELD. This solvent is VERY PAINFULL and damaging to your eyes.

Blow compressed air thru to ensure all crud is removed.

Reinstall and adjust as spelled out in the service manual.

Okay I think I'm going to have to take off my carb again and Recleaned it. I aready went through 2 bottle of
Carb cleaner. If I remember right, all my passage are clean. When spraying carb cleaner through passages inside my carb I can see it coming out from the other end. Thks for yr help
I let you know if
I can start it up. I really appreciate it.

 

[xman33]

Re: 1980 25 hp mercury outboard won't start

Starting fluid is a big No No with a two stroke as it does not have any oil to lubricate the crank and pistons.

A better solution is a bit of pre-mixed fuel in a squirt bottle.

Now, the fact that the motor does start and run with the throttle open tells us that the ignition system IS working, and your problem is still in the carb.

The idle circuits of the carb are very small, boiling it out will not clean those small passages. Often even soaking in carb cleaner will not get all the crud out.

A good spray solvent followed by compressed air is far more effective at clearing small passages.

Wally World Super Tech carb cleaner is under 2 bucks a can and is one of the best solvents I've found. Use the little tube pressed against each hole in the carb and spray thru watching carefully to see that the solvent comes out the hole inside the carb throat.

WARNING: WEAR GOGGLES or a FACE-SHIELD. This solvent is VERY PAINFULL and damaging to your eyes.

Blow compressed air thru to ensure all crud is removed.

Reinstall and adjust as spelled out in the service manual.

updated.....Ok so I rebuild the Carb today and now the motor seems a lil better but still doesn't want to start on neutral. It will now start on the fast position on throttle. I have to the fully open the throttle for it to start up. It will die out as soon as I put it in nuetral. Will start up again fine on fast position and will atomatically run on full throttle very fast until i loose the throttle slowly and dies out if i try and put in neutral or reverse. Sometimes i can hear the engine pop when trying to start up, is that bad? There is gas on my spark plugs when i pull them out, its wet and black. I even tried spraying carb cleaner in my cylinders through my spark plugs holes to clean out carbon excess. Kinda outa of ideas. Any suggestion would be nice to hear. Thanks for helping.

 

[CharlieB]

Re: 1980 25 hp mercury outboard won't start

Idle mixtures screw need to be adjusted while IN the water and idling IN Forward gear.

Starting point is 1 and 1/2 turns out from very lightly seated.

Adjust each carb to obtain 'Best Idle Speed' by making very small changes, waiting a minute or two between each adjustment. Turn adjusting screws only 1/8 turn or LESS, wait, then repeat, until you get to your Best Idle Speed while IN gear.

From Best Idle Speed, you will need even more fuel to provide the additional idle mixture necessary for crisp acceleration. Almost, but not quite 1/8 turn out. Test acceleration by rapidly opening the throttle to WOT. ANY cough, bog, or slight hesitation is aa sign the motor needs even more fuel. Adjust each just the width of the screwdriver blade slot out and retest acceleration. Repeat to perfection.

 

[xman33]

Re: 1980 25 hp mercury outboard won't start

Thanks for the info..Charlie . I be sure to do that.,,
One more question I didn't take out my core plugs( freeze plugs) while cleaning my carbs, Is it nessasary?
Should I go back and take those off and put new ones on and clean the
The carb holes which the core plugs were on. Maybe that's why I'm not getting it to fire up and fires up only when throttle is wide open. Is it hard to take off those plugs off and easy to replace. I got core plugs also that came with my gasket kit but didn't want to replace because it looks hard to take them off.

 

[CharlieB]

Re: 1980 25 hp mercury outboard won't start

You don't have to take them out, it is not easy for a novice to replace them and get them to seal perfectly.

Float height adjustment is critical to fuel mixture.

Trim the motor level, pump the primer and hold it firm while looking down the carb throats for any fuel flooding, indicating a bad float needle/seat.

If no flooding yet the primer buld seems to slowly squeeze in, disconnect the fuel pump and check the vacuum port to the crankcase for wet fuel, indicating a leaking diaphragm. If so, order a fuel pump rebuild kit.

 

[xman33]

Re: 1980 25 hp mercury outboard won't start

You don't have to take them out, it is not easy for a novice to replace them and get them to seal perfectly.

Float height adjustment is critical to fuel mixture.

Trim the motor level, pump the primer and hold it firm while looking down the carb throats for any fuel flooding, indicating a bad float needle/seat.

If no flooding yet the primer buld seems to slowly squeeze in, disconnect the fuel pump and check the vacuum port to the crankcase for wet fuel, indicating a leaking diaphragm. If so, order a fuel pump rebuild kit.

I had aready did that. I Change my fuel pump diaphragm when cleaning out my Carb. One question, if my stator, switch pack or trigger coil is bad would I still get a 3/8 spark jump. Im getting a nice jump on one of my coils but my other coil seems a lil weak but I can still get the 3/8 spark jump. Tested my coils and one is kind of out of range, the readings are not stable becuase the number are jumping all over the place compare to the other coil. Any ideas
thanks

 

[CharlieB]

Re: 1980 25 hp mercury outboard won't start

Coils need a good clean ground connection.

Any question if a coil may not be good, switch places with another, if the spark is still weaker, replace that weak coil.

You need a hot blue SNAP to ennsure it lights the fuel mixture under full load.

 

[xman33]

Re: 1980 25 hp mercury outboard won't start

Coils need a good clean ground connection.

Any question if a coil may not be good, switch places with another, if the spark is still weaker, replace that weak coil.

You need a hot blue SNAP to ennsure it lights the fuel mixture under full load.

I swap coils and sanded my ground base to bare metal and the problem still exist. I guess the only thing I can do now is to buy a new coil to see if it works.