VRO Failure; Checkout Proceedures?

I have a VRO pump on my 1987 200 HP Evinrude which is not pumping fuel. I placed a clear hose on the output and saw no fuel flowing. I also measured the output pressure. It was very low 'bouncing' around zero with each vacuum pulse. The pump is a BRP P/N 5007422 which is a pre-mix pump (no oil chamber - so I guess it is technically not a VRO) which I installed last year. It only has 30 hours on it. With such low use on the pump I'm having trouble believing the pump is truly bad. Is it possible I'm missing something...like the vacuum drive? I measured the vacuum line with the engine idling and it showed a VERY RAPID reading from 0 to 5 inches of mercury. This was measured after the pulse limiter at the input to the pump. My OMC manual only mentions the pump output pressure spec to be 3 psi, but does not discuss the vacuum pressures. I would like to fully check-out the pump before I buy a new one for $350 or so. I also pulled a hard vacuum on the pump vacuum outlet. It held with no leaks. Can anyone give me information on how to check out the pump? Likewise is there anything in the vacuum circuit I'm missing and can check?

Re: VRO Failure; Checkout Proceedures?

If you look thru my thread below, I rebuilt the VRO pump on my 1987 evinrude 225. The part numbers for the kits are listed in there. I think they, yours and mine, are the same pumps. It did not cost much, but you will need to bypass the oil injection and premix. This rebuild, the only one, only does the fuel side. Nothing fixes/rebuilds the oil side. The cost of the rebuild kit is around $40-$50. If you still have the original, it's time for a rebuild.....IMHO

http://forums.iboats.com/showthread.php?t=457212

Re: VRO Failure; Checkout Proceedures?

My guess is that the fuel pump diaphragm has cracked, which is common if ethanol laced fuel phase-separates and a super-rich mixture of water and ethanol got ingested into the engine's fuel system.

You can take your pump apart to inspect the fuel diaphragm and replace it if needed.

If your motor backfires or sneezes a lot due to a lean condition or running too cool, the check valves inside the pump that direct the crankcase pulses to the air motor could be damaged and that severely limits any pump output.

Re: VRO Failure; Checkout Proceedures?

I found some checkout procedures for the pump. They consisted of pulling a vacuum, pressurizing and listening for 'clicks' during various parts of the procedure. My pump passed. So I pulled off the pulse limiter and checked it. It appeared fine. It is the 'blue' type and passed air both directions. Now I'm scratching my head. Do I have an intermittent pump problem? It's raining now, but soon I hope to re-install the pump, check all hose connections for tight fit and see what happens.

Re: VRO Failure; Checkout Proceedures?

There is a little #10 size rod that pushes the diaphram back and forth. This some times breaks and will limit the travel of the diaphram. So even if you get a goo compression check out of each side of the pump, it still could be bad. For the hell of it split it in half by removing the torq screws. Be gental and see what is going on inside.

Check out the Maxrules web site. He has a very informative pictorial and directions on tearing one of these apart, rebuilding, and reassembling them.

Re: VRO Failure; Checkout Proceedures?

Problem solved. I installed the fuel pump and it did not work. After trying many things, I got a half gallon of premix fuel in a separate container, set it next to the motor and placed the fuel pump intake hose directly into the fuel jug. This of course by-passed the boat fuel system. The pump worked perfect. I have been chasing the wrong problem all along. I finally found the fuel line attachment point at the fuel tank (after pulling the deck - ouch!). The hose had turned to ?mush? and was leaking enough air to prevent the fuel pump from being able to pull the fuel sufficiently. It is relatively easy to replace it with the deck open. BUT I also found the fuel tank vent hose had turned to mush and was long gone. This hose runs from the fuel tank to the port side (outboard). It is foamed-in by the flotation foam Mako Marine used when the boat was manufactured. I have no idea how I will remove or replace this hose. But I guess that is a different thread in a different forum. Thank everyone for you comment. Look for the foam/hose problem in another forum.