Help !! Johnson 150 vro problem poss fuel pump ??

[Stuarth]

Hi looking for some help if possible , I have a Johnson 150 vro outboard on my boat that I just bought , on my first time in water it has shown a problem when going on full power it would go fine going slow , and when you put it on full power it will go great for about 10-30 seconds then just die as if it had ran out of petrol, if you start it up again rite away it starts no problem and away you go , no miss fire or stutters ,

Things I have tried.

Brand new fuel tank

New fuel line

New primer new fuel filter

Cleaned out carbs

New spark plugs

The only other problem I have is when starting from cold if will fire up straight away no probz but will run and cut out a few times trying to get it to heat up , if you get it to tick over and pull away it runs fine and will tick over then when you start it again you need to catch it with throttle


Any help would be great thanks

 

[Daviet]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

Have you tried to pump the primer bulb when the problem happens?
You could plumb in a fuel pressure guage and see if you are loosing fuel pressure.

 

[Stuarth]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

We did try pumping primer , it seemed to go for longer but still did die , have you any idea how you would plum in a pressure gauge ,

Thanks for reply

 

[Randy000]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

Is your primer bulb going flat? Usually you can pump up the primer bulb and it'll get hard, then the engine will run until it uses up that fuel in the carb. If you slowly from time to time pump the bulb and it'll stay running your not getting fuel to the carb. I've tried the pressure gauge before but it works off low pressure. If your diaphragm has a hole in it you'll get fuel coming out of your pulse line. A quick easy test of the pump for troubleshooting purposes on the outlet of the pump add a section of clear tubing and see if the pump is pumping fuel.

 

[Stuarth]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

The boat will run all day on a nice easy throttle will go all day it's only when you build a bit of speed up , it will go up to speed no problem then die , when we pumped the primer there was 4 of us in boat and primer is under bench seat so it was a bit of a palava lol

 

[Chris1956]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

If the primer bulb is going flat, you have a fuel restriction up stream of it, say the antisiphon valve or the fuel tank vent. If the primer stays hard, the restriction is downstream of it, say a fuel filter or strainer on the motor.

Some Johnnys have a main strainer for the gasoline under the airbox.

 

[Stuarth]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

When you say flat do you mean sucking in ? I have eliminated the inboard fuel tank by using a new plastic tank with vent new fuel line new primer new filter everything new rite into engine ,

 

[Randy000]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

By flat it won't be hard/stiff, basically full of fuel.

 

[Chris1956]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

OK, Are you using a 3/8" ID fuel line? That is what you need for that motor. Are you using the quick disconnect? If so, remove it and plumb it directly to the main strainer.

 

[Stuarth]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

Am I rite in saying you get 9mm and 10mm If so I have 9mm straight connected to my fuel tank , I spoke to owner of local Johnson repair specialist who advised that I should of used the larger diameter fuel pipe but it shouldn't cause the problems that I am having , ??

 

[Chris1956]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

A 3/8" ID fuel like looks to be 9.5MM, if my math is correct. A smaller fuel line could starve the motor at high seed. Try breathing thru a straw while sitting. That works OK. Now start to walk and still breath thru straw....then jog...then run. Straw will not supply enough air.

 

[Stuarth]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

Sorry had to go to yard and check , yeah it's 5/16 all the way , is it worth trying this then ?

 

[pn]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

pump your primer until hard, open the fuel drains on your float bowls, they all get gas? check all lines/connections for leaks. very thirsty engines on wot.

 

[Stuarth]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

Seem all to have fuel , as I say runs fine on low throttle I am going to try running a larger fuel supply line see if that helps , no signes of any leaks ,

 

[Stuarth]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

Another wee update got 3/8 fuel line and a 3/8 primmer , placed the fuel line into the bottom of my plastic tank and my friend held it it ,

Don't know if it was a coincidence but on initial start up it started well , ticked over great and pulled away with no cutting out , let it heat up then tested wot went for longer than usual then done its usual but when it stalled made a strange noise this time ,

Removed plugs when I got home and they were white - running lean

It didn't like starting after this either ?

 

[Chris1956]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

White is lean or hot, or some combo. Clean carbs, replace impeller

 

[Stuarth]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

The carbs have been done , what is an impeller ?

 

[Stuarth]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

We tried pumping primer again 2 this didn't really help ,

 

[Chris1956]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

The impeller is the rubber water pump located just above the gearcase. It supplys cooling water to the engine.

 

[Stuarth]

Re: Help !! Johnson 150 vro problem poss fuel pump ??

Hi been meaning to update this , I decided I hat put enough money into this boat and not getting anywhere , so I sold it on for a fare price explaining the problem to new owner best I could ,