60 HP 4 Stroke (2012) Fuel issue

[JDeeDotGee]

<1C216502>
Hey yall,

My Mercury is having an issue that is fuel related and before I go buying a bunch of parts, I figure I would post here.

Running WOT today and engine just bogged down and acted like I ran out of gas. It would start right back up and then sputter and die again. Found out that if I pump the primer bulb until it was hard, it would run for about 5 minutes again. I did this for 17 miles back to the ramp today... Anyway, you all think it is the fuel line or the fuel pump that is the issue? I changed the fuel pump about two years ago already.

[SilverFox579]

Try posting in the 4-stroke forum and be sure to provide engine serial number (required when posting).

Mercury - 4 Stroke / Verado

[EuropeanAM]

Moving thread to the Mercury Fourstroke Forum for you.

Please update with your Engine Serial Number (required when posting) for further assistance. Thanks!

[JDeeDotGee]

Serial Number is 1C216502. I changed out the fuel line and primer bulb assembly and still have the same problem. Fuel pump next? Or could this be a VST issue?

[rickdb1]

VST

[EuropeanAM]

Serial Number is 1C216502. I changed out the fuel line and primer bulb assembly and still have the same problem. Fuel pump next? Or could this be a VST issue?

If pumping the primer bulb firm allows it to start again and run for 5 minutes- the engine is likely running out of fuel (fuel SUPPLY problem).

That can be any one of the below items (or a combination of any):

-No fuel in tank
-Pickup Tube cracked/pin hole
-Restriction in Pickup
-Vent for Fuel Tank not working properly
-Anti-Siphon Valve (or Fuel Demand Valve)
-Primer Bulb or Fuel Line
-Fuel Filter(s) restricted
-Mechanical fuel pump not functioning properly *
-VST needle/seat/float problem

*Have seen several where the o-ring that seals the pump shaft hardened and prevented the plunger from moving when hot. Most of them would work ok for a while if disassembled, plunger cleaned and lubed well with 2-4-C, then reassembled. CORRECT method is replace pump.

[JDeeDotGee]

Thanks for the info Don. I already eliminated the fuel line, primer bulb, vent on cap, and I know I had fuel in the tank. Guess I have some more troubleshooting to do on to the mechanical pump and fuel demand valve... I can manually by pass the valve to test it, but I haven't figured out how to test the pump yet. Maybe I can just disconnect the output and turn the engine over and see if it is pumping anything out? Or just replace it and hope for the best. haha.

[EuropeanAM]

Normally a vacuum gauge is placed inline (via a tee) near the pump, and then the line is closed off or plugged while the engine is running. Monitor to see the maximum vacuum present before the engine begins to run out of fuel (which may take a while). A healthy pump should be able to pull 4+" hg (often 5+).

[JDeeDotGee]

Well... Got her fixed today. It was the mechanical fuel pump. I went ahead and replaced the whole assembly. Took the old pump apart and the two plastic o-ring valves were broken off around the rubber pins and just floating around in there. I can't believe those little o-rings are designed that way. Didn't last two years...

Fuel Pump broken valves.jpg

If I can find some of the valves I have a spare now... lol.