What drives the vromon Johnson 115

[Surgeevg22]

Hi guys,

I know I read the answer to this before but I have been searching for the answer and I can't find it.

Is there a specific cylinders pulse that drives the vro pump, and if it a specific one then which cylinder is it on a Johnson 115 cross flow engine. The pulse hose is on tHe starboard side, but there is a plug on the motor for the pulse limiter on the port side in between the carbs and starter. The plungeed up port is not in use given that it is a vro and not a fuel only pump.

I ask because I found the plug while diagnosing a fuel issue I have. That plug was loose and possible leaking. So I ask if the vro uses a specific cylinder for its pulse, or is it shared between all 4 cylinders.

Also if you have a conventional pump does it use the same cylinders pulse as the vro or does it rely on a didferent cylinder.

Thanks in advance.

 

[Daviet]

Re: What drives the vromon Johnson 115

The VRO will use the cylinder that the pulse limiter is screwed into to pulse the pump.
A conventionl fuel pump can use any cylinder to pulse the pump, just depends on the engine and how it is plumbed.

 

[Surgeevg22]

Re: What drives the vromon Johnson 115

Got it. Thank you.

Good to know that The plug on the portside was not interfering with the vro.

Thanks for the quick reply.

 

[Chris1956]

Re: What drives the vromon Johnson 115

More specifically, the fuel pump, OMS or VRO is operated by crankcase pressure. On a two cycle motor, when the piston travels down, it compresses the air/fuel mixture in the crankcase. This pressure is plumbed to the fuel pump diaghram to force fuel thru it. When the piston travel up, the pressure is released, giving the fuel pump a chance to refill with fuel, for the next cycle.

 

[Surgeevg22]

Re: What drives the vromon Johnson 115

Im taking a vacuum gauge next time i take the boat out. I know the vacuum on the suction side of the pump should not exceed 4 hg of vacuum, and it should not be 0 either, ideally 2-3 mg. But if i were to place the gauge on the fuel output side what should the fuel pressure read?

 

[boobie]

Re: What drives the vromon Johnson 115

Not less than 3 PSI.