carb or electrical??

[bob johnson]

the motor is a 2001 50 hp johnson 2 stroke, VRO disconnected. premix gas.

I sold the motor to my buddy, it always ran great...I borrowed his boat and had issues.

He didnt install a fuel filter like i suggested, nor a water seperator.

the motor was running great , then on a quick shutdown to look at something off in the distance....the motor bogged when trying to go again..

it sputtered a little and them went right back to running fine..

went a mile or so and throttled down to watch for rocks.. and the motor sputtered and would not rev on the throttle up again.

then i noticed the gas tank was almost empty...I figured it was either no gas or some junk in the bottom of the tank stuck in a carb..i switched out tanks..a tank i brought from my boat..

motor still would not rev, most i could do was about 6 mph..

when it normally can do about 30 mph.

limped in.

played with the plugs... idles fine..revs in nuetral good.. sounds OK...

at home i put on the muffs and played with the motor... switched plugs...same thing

checked the spark...with a spark tester.. both cylinders are getting good spark( looks the same in daylight!) jumps about 3/8th no issues...

when running if i remove the top plug wire you hear a noticable rpm drop...it sputters once in a while but stays running.

put it back on and take the lower plug wire off....it drops rpms more noticable than the other, but it still runs...it SEEMS to sputter a little more and once in a while sounds like it may stall...but it doesnt( actually it did once in 5 tries)

so it sounds like I have more combustion in the lower than the upper.

ok, Ill do a compression check soon...BUT

it was running strong!! till i throttled down quickly and till i got to the bottom of a dirty gas tank...both maybe coincidences...dont know yet...

I poured all the gas left into clear bottles and found a little debris from inside the tank!!!!

so question:

I know a clogged carb is one possibility....but can the power pack give me a seemingly nice spark at idle, but not be up to the task at higher rpms????

it has no power under load...

it revs good..

both spark plugs looked ok, one slightly oilier than the other...suspect cylinder a little darker...

thanks

bob

 

[tashasdaddy]

Re: carb or electrical??

sounds like you pick up trash or water from the tank. there should be an inline fuel filter under the cowl.

 

[R.Johnson]

Re: carb or electrical??

Check the fuel, and ignition linkage to see if they are going up to their full stop. Watch the engine while someone work's the control handle. Engine shut off of course. You may have to turn the prop to do this.

 

[robert graham]

Re: carb or electrical??

You needed a fuel/water separator before, now you need to get carbs cleaned and you still need a fuel/water separator. Folks will pay for preventive maintenance after they have a problem, but it's always cheaper and better to do it on the front end to save time, money, aggravation. My son did the same exact thing on his 40HP Yamaha, paid $130 for carb cleaning and still doesn't have a fuel/water separator! Go figure!

 

[bob johnson]

Re: carb or electrical??

sounds like you pick up trash or water from the tank. there should be an inline fuel filter under the cowl.

I believe there is on there, white and on the 3/8th gas line..it is positioned verticle.

I saw it yesterday....

youd think it would catch anythign that could clog a carb!!

does that mean you believe it could be the power of the spark ????

it was a sudden event.....

I had thought a short in the spark plug wire..

which did happen once before with that motor when i had it. The spark was jumping from the wire to the block...replaced the wires and it was fixed...

I was thinking to run the motor at night to check for that again.

bob

 

[tashasdaddy]

Re: carb or electrical??

check for water. they don't like to drink water. drain the bowls, then pump new fuel thru them. with help take an induction timing light in the boat, test each spark wire for constant spark. also check the compression now.

 

[bob johnson]

Re: carb or electrical??

check for water. they don't like to drink water. drain the bowls, then pump new fuel thru them. with help take an induction timing light in the boat, test each spark wire for constant spark. also check the compression now.

thanks, it is possible that water got into one carb and not the other..

to remove the bowls and drain and reinstall

what gaskets would i need, so i can do it in one night?

do you think Id have to remove much linkage??

Id hate to mess up stuff that is all adjusted...

I would like to use my buddies boat a few more times....but my mechanic had a death in the family and left town for a bunch of days and the season i want to use this boat ends in a week and a half!!!

so no time to get him to fix anything...
if there is a gasket for the bowl, can it be reused???

or is there a drain on the bowls??

thanks again for the help.

it is appreciated

bob

 

[Tim Frank]

Re: carb or electrical??

I believe there is on there, white and on the 3/8th gas line..it is positioned verticle.

I saw it yesterday....

youd think it would catch anythign that could clog a carb!!

It may have caught "anything that could clog a carb."
The in-line filter could be clogged. I'd slap in a new one. Quick and easy, and might solve the problem.

 

[bob johnson]

Re: carb or electrical??

It may have caught "anything that could clog a carb."
The in-line filter could be clogged. I'd slap in a new one. Quick and easy, and might solve the problem.

i will replace the filter , but anything that suppolies BOTH carbs probably isnt my immediate problem..

I have a spare water seperator, and i will add an inline fuel filter on the primer bulb hose...

hopefully when i check the carb bowls Ill find water...


make life easy for me!!

fingers crossed

bob

 

[Tim Frank]

Re: carb or electrical??

i will replace the filter , but anything that suppolies BOTH carbs probably isnt my immediate problem..

I have a spare water seperator, and i will add an inline fuel filter on the primer bulb hose...
hopefully when i check the carb bowls Ill find water...

make life easy for me!!

fingers crossed

bob

Why would something that supplies (or restricts!) flow to both carbs not be a possible cause?
Remover the filter and blow backwards through it into a container and see if you get a lot of %$#@@!! coming out....that should give a pretty good idea of how much junk it has picked up.

 

[bob johnson]

Re: carb or electrical??

Why would something that supplies (or restricts!) flow to both carbs not be a possible cause?
Remover the filter and blow backwards through it into a container and see if you get a lot of %$#@@!! coming out....that should give a pretty good idea of how much junk it has picked up.

because one cylinder is running fine.... so RIGHT NOW

ONE carb might be clogged....but BOTH are NOT!!

I can change the filter and protect BOTH carbs in the FUTURE...but RIGHT NOW ...

either I have a funny elctrical issue..or I have ONE clogged carb..

the problem is only one carb...

it might have been CAUSED by a bad filter that supplies BOTH carbs... and if it was bad and let stuff get by....

the bad stuff only got to ONE carb

not being a jerk here.

just trying to figure the exact problem right now, more than the cause!!!

does that make sense??

like i said before, i told my buddy to install an inline fuel filter AND a water seperator!!!

because we boat in the winter in extreme conditions.

thanks

bob

 

[bob johnson]

Re: carb or electrical??

OK, I MIGHT have found the problem..

I ran the motor just now, in the dark.

on the top cylinder( the suspect cylinder) I can see two faint sparks jumping from the cap of the plug wire to the large body of the plug!!!!

this is while the plug wire is ON THE PLUG!!

so I am getting a short from the wire to the plug itself!!!

am I to assume it is defect in the plug wire???

or is the plug bad...???

bob

 

[bob johnson]

Re: carb or electrical??

well another update...just to have closure..I guess, and not really just talk to myself!!

I switched plug wires and the problem stayed with the top cylinder...shorting out from the plug wire boot to the plug...so i went and got another plug off a spare motor I have and the problem was gone.

NO short that can be seen...motor hummms nice...havent reved it...but since the spark short is gone on the suspect cylinder, i am guessing I fixed the issue.

still wonder why it was so all of the sudden and happened right after i did a real quick throttle down...

maybe just the plugs time....right when i get to the bottom of a slightly dirty gas tank and right when i throttled down...

a spark plug starts to short out on me...

really strange...was running wot a few times in the morning....running about 30 mph...

started in a second each time...

i started that motor about a dozen times that morning...it ran great.

anyway, thanks for the ideas..

hope i didnt waste much of anyones time...

bob

 

[R.Johnson]

Re: carb or electrical??

Never try the simple first. Nobody does that.

 

[tashasdaddy]

Re: carb or electrical??

the plug casing / insulation probably cracked, causing the short.

 

[bob johnson]

Re: carb or electrical??

Never try the simple first. Nobody does that.

you know because that motor had a bad spark plug wire a few years back and acted the same way...caused me to CONSIDER it might be electrical, if it wasnt crab/fuel related.

you know you poke around a little, move this, move that, check it all...decide you cant see anything wrong and close it up...and walla...it is running good!!

you dont figure it was because you made the electrical shorts bath a little harder to jump!!!

bob

 

[R.Johnson]

Re: carb or electrical??

Yup! Nothing wrong here.