Question about VRO/fuel pump failure

[CharlesW]

Last Memorial Day weekend my old 1986 Evinrude 40 w/VRO stopped running. It didn't seem to be getting fuel. We were able to get back to the dock by squeezing the primer bulb regularly while running at idle. Don't know if that was the reason it ran, but it got us back in. After switching tanks, switching fuel lines, checking hoses and filters with no luck, I replaced the $270 VRO/fuel pump. (I wanted to retain the VRO)<br />Everything has been fine since.<br />Now the question. I kept the old pump and just now disassembled it to see what had failed after all those years. This thing looks like new inside. No cracked diaphragms, just looks absolutely new. Should I be able to see what went wrong? It was the original 3 wire pump so I don't regret replacing it, but I really expected to see some type of problem when I took it apart. Do they fail with out any visible signs of damage? Did I fix some other problem when I replaced it? I really don't have any experience with outboards, but I am a pretty fair shadetree mechanic and I am rather curious about the whole thing.<br />It won't cause me to lose any sleep, though.

 

[seahorse5]

Re: Question about VRO/fuel pump failure

A common failure from "sneezing" carbs (lean or misadjusted running) can damage the pulse limiter and sometimes the internal check valves for the air motor diaphragm. The valves are out of sight in the rectangular part just above the hose fitting for the pulse line. <br /><br />A new pump comes with a new pulse limiter, so if you replaced it, that may also have been the problem. If they carbon up from engine "backfire" or "sneezing", they don't allow a full pulse to activate the VRO pump.<br /><br />Check out the FAQ section, part F.

 

[CharlesW]

Re: Question about VRO/fuel pump failure

Thank you Seahorse.<br />A new pulse limiter was installed since it came with the new pump.<br />The old pulse limiter looked fine although it was quite different than the new one. It did not appear to be restricted in any way. <br />I did take apart the rectangular part with the check valve, and it too, appeared new. The engine has never back fired or sneezed in the one season I have owned it. Likewise, the VRO has always worked for me. Just the fuel side appeared to fail.<br />Anyway, I now have a new 4 wire pump and if it is at least as good as the "crappy" 3 wire pump, it should be good for at least 18 years. That is very likely longer than I will be boating.