Can't figure out what's wrong here.. Did I muck sth up? Suddenly lost half power :(

Fstarocka · 17 April 2016, 16:29

Can u listen to the vids and let me know what you think?

First run 3 weeks ago

https://www.youtube.com/watch?v=MZG7...e_gdata_player

Then this yesterday..

https://www.youtube.com/watch?v=tYnO...e_gdata_player

Did compression test, all three on 140 psi..

Cyl 3 started missing, boat running half the speed, carbs cleaned 4 times, check lines, for the life of me can't figure out what's wrong.

Senior member from another site says broken coil magnet shouldn't cause that, he's seen many motors with those things cracked running fine..

Did I blow something??

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Fstarocka · 17 April 2016, 16:31

Other forum here:

http://www.marineengine.com/boat-for...epair&p=534450

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VanillaIceCream · 18 April 2016, 01:09

I had a Mercury do that to me, it turned out a plastic piece of the throttle linkage under the hood had broken and would not advance the throttle, although I couldn't tell while driving that the linkage was broken.

Edit - just watched your video, I think its fuel related. Gas line or probably connector from line to engine. Swap out tank and/or fuel line and connector and go from there.

Fstarocka · 18 April 2016, 05:15

When I drain carbs they're full of fuel.. Tested pump, had good flow.. New orings on connectors.. My plastic thing also broke but epoxied it back, still holding well..

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spartacus · 18 April 2016, 06:34

What's the fuel bulb like when it starts missing a beat? If in doubt - then replace. Original or Quicksilver part. Are you getting sparks to all cilinders?

Fstarocka · 18 April 2016, 06:41

Bulb feels medium, not hard or soft.. Tried different tanks, etc. Sparks on all yes, as I posted cyl 3 was not sparking at 7 btdc like 1 was, very odd, could magnets have slipped?

The power has just basically halved, I have been mucking around and so but I'm sure it's set up close enough to run much better than that..

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matt h · 18 April 2016, 06:44

Fuel related by the sound of it. Fuel tank venting ok??

Fstarocka · 18 April 2016, 06:45

Yes, don't think it's fuel related.. Floats have always been full, twice dealt with gunk in floats and checked pump diaphragms, 3 tanks, new connection orings.. Bulb pumps good fuel.. Filter always full..

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matt h · 18 April 2016, 09:09

does it start off with being ok and then latterly dying?

Fstarocka · 18 April 2016, 09:27

In what sense, IE seconds or days? Days yes, seconds
No.. Didn't fiddle too much.. Just cleaned carbs checked Max timing etc.. Bogs on acceleration, running.. Starts and idles instantly..

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steve-ribnet · 18 April 2016, 13:23

try new spark plugs, and examine health of ignition leads - disconnect from coil packs and clean connectors on both ends.

Run engine until it bogs, then kill engine and pull the plugs - tell us the colour of each of the spark plug tips on each cylinder and smell for / look for wet unburnt fuel.

If one cylinder shows inconsistent burn, swap plugs and spark leads over with another and repeat:
If different plug now fouls you have problem with that lead or plug.
If same plug still fouls you have a problem with the ignition circuit (coil pack, trigger from CDI) or carb/fuel line on that one cylinder.

Had a 55 mariner with same symptoms - started fine and spark visible when test cranking on shore. Turned out to be a hairline crack in the spark plug insulator neck.

steve-ribnet · 18 April 2016, 13:25

Can you have an assistant pump the fuel bulb when it starts to bog? This would rule out issues with fuel pump diaphragms

Fstarocka · 18 April 2016, 15:32

Plugs are brand new.. Tried old plug in cyl 3..no difference.. Yes friend pumped bulb during bogging.. No change.

Did wot run, top two were nice tan, bottom wet fuel, like it wasn't firing at high rpms.. Thing is jumping all over the place..

All fire perfectly at idle.. Think timing is wrong somehow..

Tx for the suggestions so far.. Think I've covered fuel supply and some base settings..

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matata · 18 April 2016, 15:53

is the poor running only higher up the rev range. how does it idle. is it repeatable or reproduceable? Is the bottom plug consistently wet and the others a nice tan. Sounds very electical?? Nik

office888 · 18 April 2016, 15:54

Quote:

Originally Posted by Fstarocka

Plugs are brand new.. Tried old plug in cyl 3..no difference.. Yes friend pumped bulb during bogging.. No change.

Did wot run, top two were nice tan, bottom wet fuel, like it wasn't firing at high rpms.. Thing is jumping all over the place..

All fire perfectly at idle.. Think timing is wrong somehow..

Tx for the suggestions so far.. Think I've covered fuel supply and some base settings..

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Check the resistances and examine for cracking in the coils if you haven't already.

I have seen cases where modules work fine when cold, then when warm, they expand a little bit and the spark randomly grounds out.

Maybe run the engine in the dark and look for any arc'ing?

Fstarocka · 18 April 2016, 15:55

Bottom plug been wet .. Haven't swapped coils yet.. Only back at boat in a week about.. Really scratching head..

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Fstarocka · 18 April 2016, 15:57

I did crank it at night, saw some arcing near coil ground wires and another near plugs.. Rubber looks good tho.. Looked for cracks everywhere.. Stumped. Ran so good just the other day..

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Fstarocka · 18 April 2016, 15:59

Maybe sync link is way out? On front cover it says to set Max cranking degrees and then carb cam pickup just before the big slope to open carbs, but it doesn't specify whether to do that with Max stop touching or what...

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office888 · 18 April 2016, 16:11

Quote:

Originally Posted by Fstarocka

I did crank it at night, saw some arcing near coil ground wires and another near plugs.. Rubber looks good tho.. Looked for cracks everywhere.. Stumped. Ran so good just the other day..

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I have seen that before with automotive plug wires. The insulation has degraded with age and petroleum exposure. You will need to replace the defective spark plug wires. You may have to crimp your own. Keep in mind, most marine spark wires are simply copper cored...NOT automotive-style carbon core.

You may want to redo the grounding. Sand the surface of the attachment and check for high resistance.

Fstarocka · 18 April 2016, 16:13

Reground and cleaned all connections.. Sprayed down with switch cleaned and sanded surfaces

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