4cyl Mercury, 50hp '82' Rope Start

[Centani]

Hi Everyone
This engine has got me baffled.
It Idles rough (missing) & gets more noticeable as you increase throttle & it seems not to beable to reach WOT(5000-5500), I don't have a Tack installed. I'm not a O/B mechanic.
I'v read the Seloc manual, read all you guy's post on mercury 4cyl's in that year range.
While running at Idle I'v sprayed a oil/gas mix into Carb's-no noticeable difference. I'v pumped the primer bulb-no difference. Sprayed carb. cleaner in & around carb's to see if there was a vacuem leak-no change.
Plugs are new, spark is jumping great, even checked at night to see if there was any spark arcing anywhere-nothing.

I put my inductive timing light on each spark plug wire one at a time the light flashes beautifully.
Everthing seems to be in order, can I still have a stator or trigger problem even if it seems the plugs are firing ok ? or could the timing be out of whack ?
But timing wouldn't necessaryly create a Missing situation, I don't think. That would only cause maybe a sluggish acting engine.

thanks
Centani
Mass

 

[coolguy147]

Re: 4cyl Mercury, 50hp '82' Rope Start

syncronizations of timing and carbs


and a good cleaning of the carbs( removing carbs and taking it apart to blow through passages with carbs cleaner and air) new gaskets if needed.

might not be propped correctly.

 

[Centani]

Re: 4cyl Mercury, 50hp '82' Rope Start

Thanks, Coolguy

I did suspect possible Syncronizations.......but neither I or anybody else has messed with that......they go out of adjustment by themselves ?

and how in the world would a rough idle be caused by an incorrect prop ?

thanks
centani

 

[coolguy147]

Re: 4cyl Mercury, 50hp '82' Rope Start

ohhhh sorry. i thought you were saying that you couldn't reach WOT.

i forgot to say earlier. you should also check your compression in the motor.

my carbs on my motor weren't in-line before and as i would accelerate it was very rough. check that. butterflys in the back are all the way open.


rouch operation isn't very much to go by? vibrating? lean sneezing? sounds like it's bogging?

video?

 

[Centani]

Re: 4cyl Mercury, 50hp '82' Rope Start

Hi Coolguy
Those are great pictures by the way.

Compression was checked all were nice & even & above 100

At idle, it looks & sounds like its missing, as if a plug isn't firing properly.

However, when I check the plug wires & plugs all looks great, as said earlier I used a timing light to check each plug as the motor was idling and the light flashes perfectly on each plug.

Do you know enough of these engines to know if I still could have a trigger or stator problem even though plugs are firing ok

Thanks, Centani

 

[Tim R W]

Re: 4cyl Mercury, 50hp '82' Rope Start

I have the same year engine and had some issues with it not missing but poor starting and lack of power, my problem was carbs were gummed up also some of the 14 gauge wires coming from stator to cdi were corroded and I had to replace sections of the wires. Have you checked the plug wires for resistance?

 

[Centani]

Re: 4cyl Mercury, 50hp '82' Rope Start

Hi Tim R W

Yes I checked & had checked the plug resistance. All 4 plug wires are great.

...In the meantime a mobile marine machanic looked at it & troubleshooted the electronics he deduced it is the Switch box, by checking the whole system eliminating everthing else ie stator, trigger, plugs, wires, etc etc.

by my previous posts you'll see I had checked my plug firing with my Auto timing light and saw great flashes with a great pattern of flashes, guess he saw something I didn't. He said my bottom 2 plugs weren't firing right....& after going thru everthing else, we came to the conclusion it was the Switch box.....

I did ask him if he had some sort of tester to test for sure that it was the Switch box, he said there isn't & its a matter of elimination.

Thanks
centani
Massachusetts