Fuel issue with 86 Johnson GT 150

[daggettb]

When i start the engine, it starts right up and idles low but fine. (if i start while choking (pushing key in) it will flood the engine). The first few times i get on plane it jumps right up and runs fine. After shutting it down and starting it up a few times it is slow to get on plane, then once on plane with 3/4- WOT the boat will bog then sound like its over accelerating, this will continue then at all times while in that throttle range.

Is this a issue with carbs, fuel lines, something else?

Thank you in advance for your help!

 

[1983 ercoa 21']

A few questions so we can better help you.
when did the motor last run fine?
have you done a compression test?
does it pass a spark test jumping a 7/16 gap ? A weak ignition will flood easily.
does the bulb pump up hard? And stay that way for a few minutes? With out starting the motor?

 

[emdsapmgr]

Agree, check for spark on all 6 cyls when the engine starts to act up. Weak ignition compontents tend to fail, once the engine warms up to normal operating temps. May run fine when cold, then drop cyls when it is warmed up. A warmed up engine will tend to heat even more, if it's shut off after running. That builds up slightly more heat-since the water pump is not working. It's that just heat which affects weak components.

 

[daggettb]

A few questions so we can better help you.
when did the motor last run fine?
have you done a compression test?
does it pass a spark test jumping a 7/16 gap ? A weak ignition will flood easily.
does the bulb pump up hard? And stay that way for a few minutes? With out starting the motor?

Last time it ran fine was about a month ago, i was fishing a tournament on the river. It started after i spent almost an entire day idling backwater through sand and muck. I ended up replacing the hub, which helped with one issue but not this issue.

I took it to a local mechanic to have compression and spark tested and it all checked out after this started happening.

The bulb pumps up and gets "harder" but still weak compared to other boats i have ran. But after 20 or so seconds the bulb is weak again. (the bulb was replaced when i took it to the shop a month ago).

Water pump and impeller were replaced mid last year. Motor still spits water at a high rate.

 

[1983 ercoa 21']

Ok now I can point you in the right direction hopefully.
take the hood off,remove the air silencer ,pump bulb and look in carbs to see which is leaking fuel past needle and seat it may help to have motor slightly tilted up so fuel will run out the front rather than into the motor. When you determined which carb it is pull it and check float for buoyancy and level setting,also check needle for proper seating by simply blowing into fuel inlet and pushing float up to seat ,if you can still blow your have trash on seat or bad seat. My recommendation would be to have all carbs cleaned and checked along with fuel lines to make sure they are not breahing down on the inside.

 

[emdsapmgr]

It's normal for the fuel hose bulb to soften after the engine runs for a brief period of time. Once the engine runs and starts to draw fuel through the hose, the bulb will soften. That's normal. But the bulb should not collapse on itself. Am trying to interpret your comment-does the engine vary it's rpm's while the throttle handle is constant. For instance will run strong for a while, then slow for a minute, then run strong again? If that's what you are describing, it could be a weak fuel pump. Pump can't provide enough fuel to keep the carb bowls full of fuel.

 

[Fed]

I'm with ercoa Post #5, you could also check the primer solenoid for leaks.

When someone says easy stone cold starts without a choke/primer I say, "There's something wrong with it".

 

[daggettb]

It's normal for the fuel hose bulb to soften after the engine runs for a brief period of time. Once the engine runs and starts to draw fuel through the hose, the bulb will soften. That's normal. But the bulb should not collapse on itself. Am trying to interpret your comment-does the engine vary it's rpm's while the throttle handle is constant. For instance will run strong for a while, then slow for a minute, then run strong again? If that's what you are describing, it could be a weak fuel pump. Pump can't provide enough fuel to keep the carb bowls full of fuel.

I will look into carb leaks tonight. But the bulb does not collapse on itself just soft. Yes rpm's very at WOT drop for a split second then strong... and then it continues on and on.

 

[1983 ercoa 21']

I'm going off your input and you had stated at the beginning it would flood this and the bulb softening while not running points towards a stuck or bad needle and seat and or the primer leaking sorry I missed getting the primer in my other post I had gotten distracted lol

 

[daggettb]

Well I just pulled off the air silencer and pumped the ball. When pumped the middle 2 carbs leak. What is the next step then?

Do both those carbs share the same bowl?

 

[1983 ercoa 21']

No they do not. It should be three two barrel carbs on that year. So your middle carb has a issue with the float or the needle and seat.

 

[1983 ercoa 21']

From reading your previous post about taking it to a shop to have compression and spark tested makes me ask if you are comfortable with the task at hand? If you are you need to get a manual and go step by step removing the carb and removing the bowl to test as I stated in a previous post about blowing through the fuel inlet. If your not comfortable with the task at hand take it to the shop and have them fix it.

 

[emdsapmgr]

An 86 Johnson GT 150 is a crossflow engine. It has 3 carbs, each with dual barrels. The 3 dual barrel carbs do share the same bowl. Any chance that your carbs have plastic fuel bowls? Those came out in the mid 80's (I thought they were 1988 and 1989) and were leakers. The plastic bowls actually warp with age and are known leakers. OMC made replacement aluminum bowl kits for a number of years due to the problem.

 

[daggettb]

It is aluminum. I just picked up a rebuild kit. I took it to a shop to check compression and spark after a oil line blew and I had replaced it. I was out of town at a tournament at the time

 

[1983 ercoa 21']

Glad you have found your problem. It wouldn't be a bad idea to clean all the carbs while your at it.
from your statement about blowing a oil line hints your still running the bro.
most motors that age have been bypassed.
are the fuel lines the same age as the oil line that blew ?
you might want to take a good look at your fuel lines also.