50 h.p looses power sometimes mercuy o.b.

[steplift20]

have a 1984 50 hp mercury o.b. it runs great but sometimes the rpms cut down like im loosing cylinders and power then it will jump up again and run perfect
i took it to a machanic and after over 400 dollars he replaced the fuel tank and said it wasnt venting right
i only have one switch box but was wondering if it could cause half the cylinders to cut out sometimes?
let me know what you think

 

[Laddies]

Re: 50 h.p looses power sometimes mercuy o.b.

Sounds lik a ign. probem you need to ck for spark on all cyls.
Lack of spark, Rule of thumb 1 cyl is a box or coil, 1 & 2 cyls or 3 & 4 cyls switch the red & red/white, blue & blue/white wires at the box and if the spark swiches cyls. its the stator if it don't it's the trigger

 

[Texasmark]

Re: 50 h.p looses power sometimes mercuy o.b.

Multi cylinder engines can loose cylinders and it's hard to hear it and hard to catch it without instrumentation.
The larger the number of cylinders the harder it is to detect. BTDT

One thing you might do is when it does it again, immediately shut the throttle down and then turn the ign off. Remove the plugs and see if any are wet. That would be the cylinder(s) with ignition problems.

Mark

 

[steplift20]

Re: 50 h.p looses power sometimes mercuy o.b.

one thing i did is when it was having this problem i diconected the ign wire from the first plug, thereb was a spark and the engine ran the same with the wire disconected
then i did it to the nuber 2 plug and the same thing
then i did it to the number3 wire and could not start the engine
i didnt do it to the 4th wire so im thinking even if i got a spark from the 1 and 2 wires is it possible that that spark wasnt strong enought to fire the cylinder thats why im thinking there was no change what do you think

 

[steplift20]

Re: 50 h.p looses power sometimes mercuy o.b.

waiting for reply

 

[JUSTINTIME]

Re: 50 h.p looses power sometimes mercuy o.b.

u need a manual first
do not do the pull the plug wire thing

 

[Texasmark]

Re: 50 h.p looses power sometimes mercuy o.b.

Again, hard to tell in multicylinder engines.

You don't want to pull the wire (as Just said) because there is no gap to limit the output of the ignition coil and you can damage your ignition.

The fact that your engine had a definite change when you pulled wires from certain cylinders obviously points to lazy cylinders. The question is how lazy and why. To answer that one needs to understand the ignition particulars of your specific engine and I'm not capable of doing that......Like Just said, a manual is a good place to start. I don't have one for that engine.

Mark