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97 johnson 150 2 stroke running weird

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Avila_27

New member
Have a 97 j150exeue that I can prime up and starts up and runs for a few mins then Boggs down and I can pump the primer bulb and starts to run like it should for few mins and then I'll have to pump the bulb again. See no leaks. Replaced fuel lines and primer bulb. Have also ran off a portable tank and still some issues. Looking for recommendations. Have also put a aftermarket vro pump on and run even worse then it did with old pump
 
I like to diagnose parts before installing new parts.-------Do you have the old pump and is there something wrong with it , yes or no.--------A fuel pump is driven by crankcase PRESSURE pulses.----There may be an issue there.-------A cylinder compression test may offer at least some clues in this case.----Post your numbers.-----Carburetor float bowls are know to warp on these motors.---Have you inspected them ?
 
racerone said:
I like to diagnose parts before installing new parts.-------Do you have the old pump and is there something wrong with it , yes or no.--------A fuel pump is driven by crankcase PRESSURE pulses.----There may be an issue there.-------A cylinder compression test may offer at least some clues in this case.----Post your numbers.-----Carburetor float bowls are know to warp on these motors.---Have you inspected them ?
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All compression was tested 100 psi +/- 5 range.. old pump has bubbles pushing out a small crack where a screw was tightened to much.. have not looked at bowls for warping but I know they are not leaking. Weird befuase it runs fine and then does out some but pump the bulb and runs fine again
 
This additional information leads me to assume that your replacement ( made in China ? ) fuel pump is defective.------
 
Racerone, that is faststrike rite with optical ignition ?
If so on port side of motor where oil and fuel lines come to cowling at coupler. You have short lines going to vro pump. I would install clear short fuel line from coupler to vro. Run motor a look for air bubbles. If air bubbles bypass coupler. And see if you still have air bubbles if u do,
your sucking air , between motor and fuel tank. Another question is this a bass boat with 2 fuel tanks with splitter valve to switch from one tank to other.
 
Avil 27, if it's the motor I'm thinking . on port side where fuel and oil lines come in there is a phillips screw , remove and slid cover up lines and u will see coupler I'm talking about , bottom line is oil( should be)
 
racerone said:
This additional information leads me to assume that your replacement ( made in China ? ) fuel pump is defective.------
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I was thinking the same thing. Probably go ahead and change pump out to convert to premix and see if that fixes the issue and do away with oil injection
 
Mikey N.C. said:
Oil not the problem sounds like fuel is. Does it have cover on port side where oil an fuel lines go in ?
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Yes it has the outtle black over that then goes into a little coupler where fuel line and oil line come in to connect to vro pump and to the 2nd fuel filter at the fuel bracket
 
If you get a short piece of tygon yellow line. On junction to pump ( fuel) u will see if u are getting air . rule that out first. Quick and simple. That shows if problem is for our aft.
 
faztbullet said:
The VRO cannot pull fuel from boat side if VS top is leaking..The separator feeds the VRO
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The vapor separator isn't leaking from antrhing I can see nothing is leaking. Going to put clear hose on and run from couple where come into housing in a little bit and see what it does if there are bubbles there or not and then run from a tank straight to carb running without the coupler at the housing.
 
Avila, Racer mentioned warped bowls. They can be warped and not show leakage. Mine were not leaking gas, but apparently WERE letting air in. I was having similar issues. I sanded them down on a piece of glass and it runs great now. Just fyi
 
Mikey N.C. said:
10 -4 eliminate every thing back to boat
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Connect line from primer bulb straight to fuel bracket on motor bypassing the plastic coupler at the motor housing with no air in the clear hose and still doing same issue have to pump bulb often to keep it running or it bugs and cuts out
 
This might sound ridiculous, but... I had the same problem with a similar outboard. I zip tied the fuel line so that the primer bulb was in a verticle position rather than a mostly horizontal position, and it resloved the problem.
 
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