Sick & tired of failing Mercury fuel pum float switched failing.

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wrd1972
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Sick & tired of failing Mercury fuel pum float switched failing.

#1 Post by wrd1972 » Thu Jul 26, 2018 6:59 am

2008 ST PB 21' w/ mercury 90 4-stroke

Well it looks like its time for yet another Mercury float switch for the fuel pump, inside the VST. This one lasted 2 years. But this will be the 3rd one on in about 6 years or so. Am I the only one having this issue? Any ideas on how to prevent them from failing this frequently? I have been using Sta-Bil during every fill-up.

Thanks
2008 Sun Tracker Party Barge 21' 2 Log NV performance Package, 90HP 4 stroke Mercury. 37MPH avg. on GPS.

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wwind3
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Location: Lake Livingston Tx

Re: Sick & tired of failing Mercury fuel pum float switched failing.

#2 Post by wwind3 » Thu Jul 26, 2018 7:22 am

I bought my 90 Optimax in 2009. Broke down 5 times in 6 years.. First time ethanol had eaten up my fuel hose and rubber in fuel pump.. Nightmare

Finally took it back to Capt Kirks in Woodlands TX where I bought it.....they said there was a bulletin out that told about a fix for it. I've been running almost 4 yrs now.
I was on a first name basis with Mercury in Wisconsin===owned 9 Mercs--FIRST one that ever gave me trouble. I'm still mad about it. And I let everyone know about it. Was afraid to take the boat out with anyone else with me.

Maybe your dealer has a fix--ask them about a bulletin--or better still call Merc in Wisconsin...maybe they know something now dealers don't. In fact--call them FIRST. And raise hell with them...might get a free fix this time. I use the Startron in mine now.

Good luck....
2009 LOWE SS204 25in logs
90 Merc Optimax
Motorguide W55 Wireless
Underskinning
28 GPS

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FLOUNDERPOUNDER225
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Re: Sick & tired of failing Mercury fuel pum float switched failing.

#3 Post by FLOUNDERPOUNDER225 » Thu Jul 26, 2018 9:19 am

I know lots of folks who still run ethanol, I gave it up 6 years ago in anything but my daily driver vehicles. I have seen so much destruction of fuel system components in outboard motors, even with after market additives. My advise to everyone is if you can get non-ethanol gas: https://www.pure-gas.org/ use it for your boats and yard equipment, it will virtually eliminate your fuel issues. Here is your Mercury VST Fuel pump after sitting with ethanol in the VST. Locked up solid, wouldn't even run from the corrosion damage.
vst pump.jpg
vst pump.jpg (234.98 KiB) Viewed 2778 times
Pensacola FL
2015 Berkshire 231 RFC
Yamaha F-150

wrd1972
Posts: 236
Joined: Sun Jul 31, 2011 8:37 am

Re: Sick & tired of failing Mercury fuel pum float switched failing.

#4 Post by wrd1972 » Thu Jul 26, 2018 2:29 pm

Dont get me started on the dealer. I hate them all. I can easily do the mechanic work myself fortunately.

Also, i am stuck with dock gas. It sits in a dry slip beside the lake.

Would there be any value to cutting fuel to the vst and letting it run dry when done for the day. So that the vst is dry when rhe biat is nor in use.
2008 Sun Tracker Party Barge 21' 2 Log NV performance Package, 90HP 4 stroke Mercury. 37MPH avg. on GPS.

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wwind3
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Re: Sick & tired of failing Mercury fuel pum float switched failing.

#5 Post by wwind3 » Thu Jul 26, 2018 3:41 pm

I asked that question--I was told my motor has a couple of fuel pumps and to drain all the gas would take a while to empty everything.. I cant vouch for this but was told not to try it--not worth it.

I also thought about running from a 6 gal tank but was told I couldn't run a pre-mix. Not sure if I can run from a side tank. Maybe I can. That way gas wont sit in the big tank forever and go bad.
2009 LOWE SS204 25in logs
90 Merc Optimax
Motorguide W55 Wireless
Underskinning
28 GPS

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ROLAND
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Re: Sick & tired of failing Mercury fuel pum float switched failing.

#6 Post by ROLAND » Fri Jul 27, 2018 1:11 am

wwind3 wrote:
Thu Jul 26, 2018 7:22 am
I bought my 90 Optimax in 2009. Broke down 5 times in 6 years.. First time ethanol had eaten up my fuel hose and rubber in fuel pump.. Nightmare I use the Startron in mine now.

Good luck....
I agree.. ethanol fuel is a nightmare... but I'm fortunate in that there are several ethanol free stations in my area.. I would imagine in 9 years of boat ownership I probably have only run 2, maybe 3 tanks of gas that contained ethanol... as for startron, I've heard that it's a good product. Personally I have been using pri-g. Havent had a fuel related issue since day one..
Roland & Jo
2010 Bennington 20 Sfi
Yamaha 75 4 Stroke
Shreveport, Louisiana

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FLOUNDERPOUNDER225
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Re: Sick & tired of failing Mercury fuel pum float switched failing.

#7 Post by FLOUNDERPOUNDER225 » Fri Jul 27, 2018 7:17 am

wwind3 wrote:
Thu Jul 26, 2018 3:41 pm
I asked that question--I was told my motor has a couple of fuel pumps and to drain all the gas would take a while to empty everything.. I cant vouch for this but was told not to try it--not worth it.

I also thought about running from a 6 gal tank but was told I couldn't run a pre-mix. Not sure if I can run from a side tank. Maybe I can. That way gas wont sit in the big tank forever and go bad.
when dealing with fuel injected motors, 2 or 4 stroke there are 2 fuel pumps, you have the vacuum operated pulse pump (low pressure) that bolts to the engine, and is a lift pump which moves the fuel to the VST where the electric fuel pump boosts the pressure to around 50ish then sends it to either a high pressure pump (Yamaha HPDI motor, or similar 2 stroke) or directly to the fuel injectors. and no, you cannot run a pre-mix with a fuel injected 2 stroke, it would probably damage the injectors, as they are only designed to inject gas, the oil is injected in the plenum area and sucked into the combustion chamber when the reed valves open. any other way you could lean a cylinder out and that will cause catastrophic damage.
Pensacola FL
2015 Berkshire 231 RFC
Yamaha F-150

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wwind3
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Location: Lake Livingston Tx

Re: Sick & tired of failing Mercury fuel pum float switched failing.

#8 Post by wwind3 » Fri Jul 27, 2018 4:33 pm

Flounder----thank you for this! Too bad some dealers wont tell you these things. Hopefully my last dealer fixed it--still like Russian roulette every time I go out--sux….
2009 LOWE SS204 25in logs
90 Merc Optimax
Motorguide W55 Wireless
Underskinning
28 GPS

brumbyvet
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Location: Cherokee Lake, East Tennessee

Re: Sick & tired of failing Mercury fuel pum float switched failing.

#9 Post by brumbyvet » Sun Jul 29, 2018 8:12 pm

I have the same boat and motor as OP. I've always used 100 percent regular gas with stabil marine blend with every tank. The only problem I've had is with the fuel pump diaphram leaking gas into the oil. It has been replaced once and so far, so good. That and water pump replacement every two years has been only service by dealer. I do my own oil and lube changes.
2009 Sun Tracker Party Barge, NV Performance Package, 90 HP Merc 4 stroke
36 mph gps...
Cherokee Lake, Tennessee

U.S. Navy 1971-1977

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