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Great Forum Here!-Gotta' Problem 1994 150hp

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Swampbilly

New member
Hey guys,.
I'm running a 1984 Johnson 150 on my V-20. Had the carbs re-built last May. Afterwards, she ran great and used it all summer, every weekend. I noticed however, that after running for about an hour and shutting the motor off, that it gradually became harder to start after it sat for a short period of time-(30min.). You could smell gas. Had to choke it eventually to get it started, and then she was a little sluggish initially when throttling up, and then it would clear up and run fine untill you shut it off again and it sat for a short period.

Now this year, you can run about 4-6 miles, and the motor will bog down and shut off,..you can smell gas, and it appears to be flooded up...Won't start untill it sits for a few hours. When I disconnect the fuel line to the motor,..there's significant pressure , and gas shoots out from the connector on the motor. I replaced the fuel line (bulb), as one time it was collapsed which made me think the pick-up was clogged in the tank...The 90deg. elbow that goes into the tank (for pick-up) is WELDED ON, so it cannot be removed to check the pick -up, (ain't that a crock?). I checked to see if the check-ball (anti-siphon) was sticking in the tank possibly from Ethanol contamination..there was no checkball. I'm kinda' stumped here. Thots?....
 
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Re: Great Forum Here!-Gotta' Problem

well you did say in your previous posts that you found the primer bulb on the line was soft correct? this is an indication that your fuel pump is not working correct.

the fuel pump should be putting out around 5-7 psi for it to be working correctly, now the fuel pump will not work correctly if the cylinder that it is operating for does not have the right amount of compression.

can you do a compression test on the engine and let us know the results please?
 
Re: Great Forum Here!-Gotta' Problem

omc_10 said:
now the fuel pump will not work correctly if the cylinder that it is operating for does not have the right amount of compression.
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...Ahh, I just learned something from you here. Compression is low,..90-100 betweeen all 6 , had it checked last year as well...Is that too low? The Bulb- the bulb was collapsed at one point and when I disconnected from the motor, there was back pressure from the motor and fuel shot out of the connector (from the motor, not the fuel line with the bulb feeding it.
 
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Re: Great Forum Here!-Gotta' Problem

so you did a compression test right now?
and they all were between 90-100psi?
the main thing is that they are within 10% of each other not like one is 80 and the others are 100.
 
Re: Great Forum Here!-Gotta' Problem

omc_10 said:
so you did a compression test right now?
and they all were between 90-100psi?
the main thing is that they are within 10% of each other not like one is 80 and the others are 100.
Click to expand...
..No, these were figures from last year. It could have changed I suppose. I'll get it checked.
 
Re: Great Forum Here!-Gotta' Problem

check it yourself does not take much at all you can buy a compression tester from local stores such as canadian tire or walmart.

with all spark plugs out turn the engine over for about 3 seconds and then write down the reading make sure you mark what cylinder is which. shouldnt take longer then 10 minutes.
 
Re: Great Forum Here!-Gotta' Problem

omc_10 said:
check it yourself does not take much at all you can buy a compression tester from local stores such as canadian tire or walmart.

with all spark plugs out turn the engine over for about 3 seconds and then write down the reading make sure you mark what cylinder is which. shouldnt take longer then 10 minutes.
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Gotcha' omc', thanks again. I'll do that. I thought it had to be a "special" kind of compression guage for marine motors. I'm learnin' something here my friend...:cool:

I thought the bulb was collapsed, and when I say collapsed,.. It appeared to be "sucked" flat, which made me think the fuel pump was o.k..
 
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Re: Great Forum Here!-Gotta' Problem

hey man no problem :)
try to help as much as i can still a young pup (18) i am trying to learn also
 
Re: Great Forum Here!-Gotta' Problem

No, I'm out of town untill tomorrow. Are the cylinders marked as what each # is on the left and right bank? And speaking of left and right bank,..is that looking at the motor from the front (inside the boat) , or behind, facing the cylinder heads/sparkplugs?
 
Re: Great Forum Here!-Gotta' Problem

In regards to your fuel pump test here are the instructions..
When working on a fuel system, check for any restrictions or air leaks which would affect the engine. You can use a clear piece of fuel line connected to fuel pump inlet and "T" off to a vacuum gauge. Run the motor at all speeds while inspecting for air bubbles in the line and for any vacuum restrictions above 4-inches Hg. A system with 3/8-inch fuel lines, a clean "spin on" filter, and a quality anti-siphon valve should show between 2.5 to to 3-inches of vacuum at full speed.

Check and inspect all your fuel hoses, clean and inspect your jets and float. You smelling gas is a no no, check for leaks..stuck floats ?
 
Re: Great Forum Here!-Gotta' Problem

first off thanks NTBRAN for the fuel pump help

second i am not sure of the cylinder number but look from the back of the engine (looking at sparkplugs) just start from top left middle left bottom left then move to right side. if you follow the spark plug wires there should be a number where they end or something indicating which is which. not sure if this number has worn off though since it is an older motor.
 
Re: Great Forum Here!-Gotta' Problem

Just on the off chance here, run the motor with the cap on the fuel tank open and see what happens.
 
Re: Great Forum Here!-Gotta' Problem

He mentioned that the fuel bulb was sucked flat...that would indicate a plugged vent for the gas tank. With the cap off, the tank would be vented.
 
Re: Great Forum Here!-Gotta' Problem

2 1
4 3
6 5

from the back of the motor, this is how the cyl are numbered.
 
Re: Great Forum Here!-Gotta' Problem

Compressions fairly typical. If it were my boat I would look for a carb or two that is overflowing. I would first rule out the fuel system by running a new 6 gal can with a new hose and bulb. That will tell you if you have a restriction, fittings leaking air, etc.
 
Re: Great Forum Here!-Gotta' Problem

martino1 said:
Compressions fairly typical. If it were my boat I would look for a carb or two that is overflowing. I would first rule out the fuel system by running a new 6 gal can with a new hose and bulb. That will tell you if you have a restriction, fittings leaking air, etc.
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...Yeap, I realize this motor is getting a little "tired" compression-wise, I ran it once on a 6 gallon (new) tank with new line and it ran like a scalded cat. I want to run it again with a couple portable tanks to eliminate, (or include) the 55gallon tank as a problem. Seems like it runs ok on the portables. Can't run with the gas cap off, I'll splash fuel in the drink, (the tank is full).I was looking for a pick up tube with a screen in the large tank (55gal) and couldn't see one..how the heck does fuel get into the line without one??
 
Re: Great Forum Here!-Gotta' Problem

Swampbilly said:
...Yeap, I realize this motor is getting a little "tired" compression-wise, I ran it once on a 6 gallon (new) tank with new line and it ran like a scalded cat. I want to run it again with a couple portable tanks to eliminate, (or include) the 55gallon tank as a problem. Seems like it runs ok on the portables. Can't run with the gas cap off, I'll splash fuel in the drink, (the tank is full).I was looking for a pick up tube with a screen in the large tank (55gal) and couldn't see one..how the heck does fuel get into the line without one??
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So you're saying since you started having the problem, you tried a new 6 gallon tank and it ran great?

I think you need to get back to basics - like the guy above said, the collapsed bulb is often a classic sign of a fuel restriction upstream of the bulb, including a bad vent or anti siphon valve. IF (again, I'm assuming here), the 6 gallon tank solved the problem, that's a big clue!
 
Re: Great Forum Here!-Gotta' Problem

You don't need to run it with the gas cap off, just crack it open enough to let air in or out.

If it is the problem you will hear air being sucked in. Leave it like that and run it and see what it does.
 
Re: Great Forum Here!-Gotta' Problem

d.boat said:
So you're saying since you started having the problem, you tried a new 6 gallon tank and it ran great?

I think you need to get back to basics - like the guy above said, the collapsed bulb is often a classic sign of a fuel restriction upstream of the bulb, including a bad vent or anti siphon valve. IF (again, I'm assuming here), the 6 gallon tank solved the problem, that's a big clue!
Click to expand...

......Gonna' try it again there, d.boat..It ran "fine" on the regular tank as well up to a point. So, the process of elimination continues....:)
 
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