Float switch problem

[G48]

Hi, My '09 115 hp 4s efi s/n 1b738471 is headed to shop Wednesday for what appears to be a faulty fsm float switch for the 2nd time. It was replaced the 1st time in March 2016. The symptoms were loss of power at wot and then after coming off plane would not idle and died..refused to crank. vesselview threw code 3075-28.. lift pump timeout. When i turn the key on I can hear the pumps priming but takes longer than normal to stop. Is this a pump or float problem or fuel leak? I have had a fuel smell throughout the boat (mainly behind console area) under deck since new but thought that was from normal venting. It's a 18' nitro x-5 with a 26 gal. fuel tank.

I was told by a tech that the pumps should last the life of the engine and it could be a hairline crack in fuel tank. I currently have about 7 gals. in tank. I had the fuel line upgraded via warranty. Should the switches go out that frequently as well? I've had some unrelated over heat issues recently as well running wot thru giant salvenia patches... but was able to recover water pressure by coming off plane and reversing out to clear debris. That wouldn't have anything to do with the fuel problem I wouldn't think??? Anyways, TIA for the responses!! Gary

[EuropeanAM]

Lift Pump Timeout does NOT necessarily mean that the float is bad. It means that the pump ran longer than SHOULD have been required to completely fill the FSM.

Since you are "smelling" fuel, it would be wise to investigate that. A leak in the fuel supply line or fittings- anything between the fuel level and the FSM (or a restriction) can and will cause excessive pump "on-time" (resulting in a Lift Pump Timeout).

Normally if the float is the problem, it either does not signal for the pump to come on (engine runs out of fuel), or does not signal for the pump to turn OFF (potentially flooding the system).

[G48]

Thanks Mr. Don.. Tracker marine replaced the 1st switch and I suspect since this smell was apparent since the 1st day I bought it that their wasn't much troubleshooting the cause of the switch failure.

[EuropeanAM]

Suspect the Float switch that failed back in 2016 is unrelated to your current problem (even if you do happen to have a failed float switch now).

[G48]

Dealer has ordered the switch..apparently my engine is antiquated.. it was ordered last Wednesday and the still don't have a tracking # as of today. They don't seem motivated to investigate the cause of the failed switch just that it was bad and the pumps are fine. So i guess I'll do my own research. At the time of the 1st failure I had prolly 80 engine hours but have been spending more time in it the last few years accumulating up to 130 hours now. Just wondering if others are having this issue with lowish engine hours and repeat float failures thereafter. Don't know ..just seems odd the switch failing multiple times. I have noticed on other forums people having similar issues but not widespread. Might be wise to order a couple for backstock for the eventual repeat failure so I don't have to wait on parts.

[garyle]

For what its worth I had a similar issue a few years back. Lift pump kept timing out and had to purge the fuel rail to restart. Traced it back to the back flow tank spring being too strong and an air leak in the water separator. Found out by pulling vacuum on the fuel line from the engine back to the tank fitting. Ended up loosening up the backflow spring and ditched the water separator all together. Also replaced the FSM as that job is a big dollar bear and didn't want to chance it happening again. Zero problems after but now I run fuel cleaner with every tank just to be sure about keeping water in check.

[EuropeanAM]

G48... there is only so much investigation that can be done to a simple "on-off" float switch. Essentially... like a light-switch or a light-bulb, it's either good and working properly, or it's not (and you replace it).

The only real exception is that ethanol percentage in the fuel can potentially be a contributor to float switch deterioration or failure. Anything over 10% ethanol content is going to cause problems with fuel system components.

[G48]

Got the switch in, dealer had no explanation for premature failure. I have a couple of ideas...could the use of non ethanol with the proper "cocktail" over time have anything to do with it and/or would my 100 ah ionic lithium starting battery have anything to do with it. I ask about the battery since it stays fully charged via alternator and although this battery has an upgraded bms that keeps my running voltage about 13.8v at the analog gauge, I'm curious how the excess voltage from the alternator is handled? I would assume it is regulated somehow but could that cause the premature failure (backfeeding somehow)? Just spitballin..very curious. The boat ran better on this outing getting 33-34 psi at 6000 rpm and 42-43mph and no rasping engine noise after coming off plane and idling up to 5 mph afterwards. Anyways, it took my dealer about 8 days to come up with the part so I'm contemplating just ordering a spare for backup so I can present it to the dealer on my next unfortunate "lift pump timeout" code that pops up on my vvm. Engine getting older it appears that the parts for it are getting scarcer thru the traditional supply chains. I called some other local dealers and asked them about it and no one had 1 in stock nor did their sister locations within a 300 mile radius. They say they're constantly upgrading the part but can't seem to find a superceded part for merc 8M6000359. Appreciate the replies...TIA!!

[EuropeanAM]

Non-Ethanol and/or cocktail: no.

Battery: no.

Most of the time, stock levels at dealers are based on previous/current demands for the part. I know that we used to sell this part quite regularly, but in the last few years the demand has tapered off (meaning that it is not necessary to keep multiple items in stock).

As suggested- don't overthink the failure. Sometimes the reason is just simply "it failed".

And they're right, 8M6000359 is the latest and greatest part number.

[G48]

Thanks Don, Another issue though... 3rd trip otw yesterday since switch replace and it died on me again with the same "lift pump timeout" code and trolled back to the launch. Tried calling the dealer while otw and they are closed on Monday's...so I will make an in person visit this a.m with a video of the motor choking and sputtering and emitting white with what looked like a tinge of yellow smoke coming from the exhaust. After the engine quit it would puff alittle smoke then quit and puff alittle more..It did that same action 4 or 5 times before the smoking stopped. Some of the water was covered with surface vegetation I was going wot thru but as soon as my water pressure dropped I came off plane and did a back flush and started again. Only had to stop 3 times to do that. Would choking the water pressure trigger the failure? I know the fuel and water pressure issues are exclusive events but I'm trying to think outside the box because this is starting to get expensive. What else do I need to look for (or suggest to my dealer) that is causing this extremely premature float switch failure? This is driving me crazy with all the possibilities.! would it be the fact that my dealer told me he added 5 gallons of fuel on last repair because the analog gauge was showing dead on the empty mark. It was not empty..the gauge will drop much below empty before running out of fuel. I had run out of fuel by accident but noted the gauge level to see just how much fuel it took to get it to the dead on "e" mark. Right at 8 gallons. So I changed my fuel level on my vvm to match his addition (assuming he put)of 5 gallons which put me at 12.8 gallons. The fuel reading on the vvm was 6.5 gallons when it died a slow death yesterday. I have a 26 gallon tank and normally don't like till fill it above 20 for the ride. I did have tracker marine audit the fuel sending unit with analog gauge a couple of years ago and they verified it's accuracy. Thanks for the replies...Gary

[EuropeanAM]

"Lift Pump Timeout" does not necessarily mean that the float switch has failed. It simply means that the float switch did not signal the VST was full within the maximum time it should take to fill.

This can be caused by a fuel supply restriction, no available fuel, vapor-locking, or a weak lift pump (usually if it is the float switch, there would be likely other faults involved as well).