Johnson 150hp j150plees update. Motor still surges

jamesbaud

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Mar 29, 2009
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Ok, since my last post I found I had a blown head gasket, fixed it. Had a bad ignition coil, fixed it too. Bad ignition switch, fixed it. But I cannt figure out the surging problem. I've replaced the gas line and primer bulb from tank to motor. I've replaced the set and needle valve in the vapor bowl. I've rebuilt the fuel side of the vro2 pump. Rebuilt the carbs and cleaned the throttle bodies. Now I'm not sure where to turn next. Maybe the vapor pump? The pickup line and anti-siphon valve? And what exactly are those little tubes in the carbs when you open the bowl, are they some kind of pickup? Not sure if I cleaned them good enough?
 

schematic

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Re: Johnson 150hp j150plees update. Motor still surges

There are 2 ways to repair. Most people like shot gun approach in where you throw parts at it. I prefer to troubleshoot and prove before replacing parts.

Tee in with a section of clear hose in the outlet of the VRO. Check pressure and look for air as well. Low pressure will cause surging as well as air. Just because you rebuilt the fuel side doesn't mean its pumping good. A "dragging" oil piston within the pump will cause low pressure.

If pressure is within specs (3-5psi) and no air is present, you have eliminated fuel supply. If not, let us know and we'll continue with the next step.
 

jamesbaud

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Re: Johnson 150hp j150plees update. Motor still surges

Ok, but I pumped the primer bulb when running and surging. Would that make a difference? It did not make a difference in the surge.
 

schematic

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Re: Johnson 150hp j150plees update. Motor still surges

Ok, but I pumped the primer bulb when running and surging. Would that make a difference? It did not make a difference in the surge.

not on that system. the pump is isolated by the float valve.
 

jamesbaud

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Re: Johnson 150hp j150plees update. Motor still surges

Are you talking about the float valve in the vapor bowl?
 

schematic

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Re: Johnson 150hp j150plees update. Motor still surges

Are you talking about the float valve in the vapor bowl?


Correct. squeezing the primer will only fill the reservoir. It will not force fuel through the fuel pump as a generic system does.

Thats why its important to check pressure and get some direction.
 

jamesbaud

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Mar 29, 2009
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Re: Johnson 150hp j150plees update. Motor still surges

Thank you I'm finally getting some answers that I think are really going to help? I'll have to get the test gauges.
 
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