johnson 150 will not plain?????????

[ant270]

yes I have a 1987 johnson 150 the boat runs great at idle and maybe 1/16 trottel after that it chokes real bad but then it comes to life and doses this over and over and then sometimes it will run great for say 15min and then slow down and choke itself again cleaned carbs new fuel lines cleaned vent on tank new plugs has spark if someone could help please.
thanks anthony

 

[emdsapmgr]

Re: johnson 150 will not plain?????????

It may be starving for fuel. Could be a weak pump, fuel restriction in the line or tank.

 

[Texasmark]

Re: johnson 150 will not plain?????????

What is/was the squeeze bulb doing when it chokes down? Is it hard (firm) or collapsed?

Did you try squeezing it when it bogs? If so, what happened?

Mark

 

[Texasmark]

Re: johnson 150 will not plain?????????

Have you put fuel stabilizer in your fuel tank? Had a problem once with alcohol jell clogging the fuel line (kinda floated around and attacked me at it's discretion). I put in a moisture absorber previously (which contained alcohol) and it grabbed the water alright, made one gooey blob. Finally got stuck right at the fuel connector to the engine.

Mark

 

[ant270]

Re: johnson 150 will not plain?????????

today put a new $290 fuel pump in because a local shop said it was no good had a cracked diafram took out tonight same problem put stabilizer in tried a 5 gallon tank. same problem likes to go when it wants to I think by now I have taken all fuel problems out of the pic but it seems to me that it is a fuel problem. now I read that it may be a bad slow or safe switch where is that or could that not be any help would be great fishing sucks when it takes 20 times longer to get somewhere

 

[jtexas]

Re: johnson 150 will not plain?????????

Step by step process of elimination.
Start with compression test and spark test.
You suspect it's going into SLOW mode - have you verified that it's not overheating? When was your last water pump change?

When you cleaned the carbs - did you disassemble, soak, install new carb kits? Including new needle valves & seats?

That must be some fuel pump, for $300...wonder why they didn't diagnose your problem?

 

[ant270]

Re: johnson 150 will not plain?????????

hey thanks for some help well compression is good and I have spark at all 6 cyl and no i did notrebuild the carbs put new gaskets and cleaned them. but last night when driveing it i found that if when it cuts out and starts to run ruff if I slam the trottel back and then forward fast it starts to go agian had this work for me about 85% of the time do you know what that may be. And that fuel pump had some cracks in the case and in the diaframe. but they never saw the pump I told the guy my symtoms and he said its the vro pump. thanks any help great.

 

[ezeke]

Re: johnson 150 will not plain?????????

Have you tried running on a portable tank or removing the backflow preventer?

 

[ant270]

Re: johnson 150 will not plain?????????

I ran a portable tank but what is a back flow preventer??

 

[james williams]

Re: johnson 150 will not plain?????????

``i did notrebuild the carbs put new gaskets and cleaned them``. quote. I belive your carbs. are stopped-up.The jets need to be cleaned.

 

[ezeke]

Re: johnson 150 will not plain?????????

Most built-in tanks have a spring loaded device that allows fuel to flow only one way. They are usually at the outlet [hose connection]. They are notorious for getting clogged and slowing or even stopping the flow of fuel. The pickup at the bottom of the tank can do the same thing.

 

[ant270]

Re: johnson 150 will not plain?????????

ok first is why if the jets are gummed up why does the boat go sparatically and also go when you slam the trottel back and forth???????? second is ran a ex tank and it did not change any more help would be great also just so you know I never work on a boat before Im a car tec not a boat tec but I try so I can learn more Thanks you for all the help.

 

[james williams]

Re: johnson 150 will not plain?????????

Each carb has three jets,not all jets are stopped.

 

[ant270]

Re: johnson 150 will not plain?????????

what do you mean?

 

[ezeke]

Re: johnson 150 will not plain?????????

Your carbs have two high speed jets at the bottom of the float bowls where they pick up anything that sinks or settles there. There is one directly behind each drain plug.

 

[ant270]

Re: johnson 150 will not plain?????????

this could be my problem? and why does it work speraticly and when you move the trottle back and forth quick? thanks for the help

 

[Zep--]

Re: johnson 150 will not plain?????????

*maybe because when you move back and forth the semi-stopped up jets get a little fuel in them but not enough to sustain it for long.

Carl
*just a guess, i'm not an expert...yet.

 

[ant270]

Re: johnson 150 will not plain?????????

but the thing is that it will run for 5 min or 1 min or ten min after it clears up from moving it back and forth. thanks

 

[Zep--]

Re: johnson 150 will not plain?????????

my 71 johnson 60 HP does basically the same thing. it will run great for anywhere from a minute to 20 minutes, then all of a sudden, it's fuel starved. if I keep reving it up and down it will continue to run, but even then not for long most times.

I'm rebuilding the carbs shortly to see if that solves my problem. I don't think it's the fuel pump because when it does die, if I screw out the drain plugs when this happens, all carbs are full of fuel.

you might consider a carb rebuild.

Carl

 

[ezeke]

Re: johnson 150 will not plain?????????

The primer bulb and fuel pump keep the float bowl full when everything is working right.

The operation of the pistons pulls fuel mix into the firing chambers through the carbs and leaves.

If the fuel supply is working correctly and you have compression, air, gas and fire, then it usually comes down to balance. Right now, it sounds a lot like carburetors- but you have to remember that we have never seen your motor.

There are a series of capillaries running from the jets, a/k/a orifices, to the carburetor throats that can easily clog and cause your symptoms.