Johnson 150 1990 fuel line pressure

[mwh086]

The primer bulb on my 150 will become tight when pumped, but soft after the engine runs. It then becomes hard to start until primed again. I have replaced the bulb with no change in performace. I would assume there is an air leak between the bulb and the VRO pump that is allowing air into the line.

Any thought or experience in this area?

Thanks,

Mark

 

[wilde1j]

Re: Johnson 150 1990 fuel line pressure

Bulb does not remain hard after motor starts and is not supposed to.

 

[mwh086]

Re: Johnson 150 1990 fuel line pressure

OK.....I like that answer!

But the bulb feels like there is no fuel in it.......

and why is the engine so hard to start unless you re-prime using the bulb.

Once reprimed the engine runs great until I stop and then repeat.

If there is any correlation, the engine dumps about 4 oz of 2 cycle oil into the transom well when tilted up to trail the boat, if that means anything.

Mark

 

[jonesg]

Re: Johnson 150 1990 fuel line pressure

Try to position the bulb so the flow arrow points up toward the sky.

Check for oil leak around the pump, clean it up good with paper towels, pressurize the fuelo system and look for leaks, around the carbs too.
It might just be flowing out the carb throats when tilted.
You should have a drain hose from the bottom of the airbox to the crankcase.
www.outboardbooks.com
get the manual, you can't figga these engines out by looking at them.

 

[wilde1j]

Re: Johnson 150 1990 fuel line pressure

A fuel delivery problem, can have a number of causes, such as:
. air leak on pump suction side (bad clamp, cracked hose, cracked tank pickup tube, etc., etc.)
. malfunctioning anti-siphon valve
. plugged tank vent
. trash blocking tank pickup screen
. plugged fuel filter
. collapsed fuel line
, bad fuel pump

Is the bulb getting sucked flat, or just empty? Most of the above except the first can cause that too.

 

[mwh086]

Re: Johnson 150 1990 fuel line pressure

The bulb does not go flat as if by engine suction, that is why I suspect an air leak after the bulb. As if the hose had a pin hole leak that allowed air in to the line between the bulb and motor.

Mark

 

[jonesg]

Re: Johnson 150 1990 fuel line pressure

Air leaking in means fuel leaking out, look for damp hoses around clamps.
Pump the bulb up to pressurize the system and use a flashlight to inspect.

 

[emdsapmgr]

Re: Johnson 150 1990 fuel line pressure

The 1989 engines used tywraps on all the fuel system hoses. These tywraps tended to loosen somewhat with age and could cause leaks. The 1990 models switched to the snap clamps-a much more positive type clamp. Check your engine and see which type clamps are on your engine's fuel hose system. If yours was a very early 1990 and has the tywraps, you may want to change them all out.