Float Valve Sticking on 4hp Tohatsu MFS4A2D Model trolling motor

[Toconn87]

RE: Float Valve Sticking on 4hp Tohatsu MFS4A2D Model trolling motor

I have had problems with the fuel tank leaking on my 4 hp Tohatsu trolling motor from the strange rubber hose that connects the top of the fuel tank to the bottom for an unexplained and seemingly unnecessary reason.

The plastic nipple on the tank was broken, so the dealer removed the rubber house, and filled the holes with rubber washers and screws which stopped the leak. But the first time I took it out for the season two weeks ago, the motor wouldn't start...so I pulled it 3 hours back to the dealer and he started it right up, so he thought the float valve was stuck and must've bounced loose on the drive home. He also told me to turn off the gas and run the carb out of fuel when I'm on the water, so that the carb has no gas in it (and he did this).

The next weekend, I pulled the boat 3 hours back to the river, and when I dumped it into the water in the morning, the float was stuck again and the motor wouldn't fire unless I was spraying gas into the carb (which I did by filling a quart sized ziploc bag with fuel, cutting off a corner, and squeezing the bag). I kept tapping the carb as I was spraying (as the dealer had advised) and eventually broke the float pin free and it worked great the rest of the day. I left the gas on (intentionally) so gas would remain in the carb and then next day it fired on the first pull and ran all day.

The dealer says I should get a new carb kit installed, to prevent this in the future. I'll do that if necessary, but I'm also curious if removing that internal hose that connects the top of the tank to the bottom of the tank could be the reason that I'm having this problem.

Any help is greatly appreciated.

 

[pvanv]

Re: Float Valve Sticking on 4hp Tohatsu MFS4A2D Model trolling motor

The hose on the tank is to allow complete filling and draining of the tank. It's an equalizing vent. It might work OK without it, though. Personally, I have never disabled one.

Yes, it's always best to run the carb dry.

If the needle is sticking, a cleaning may help. That may end up requiring a kit be installed. If it's much more than a nuisance, just put a carb for the 6A2 on the motor. You get 50% more power, and about the same cost Labor/parts for cleaning may approach the $116 for the new carb.

The internal tank flows by gravity only, until the motor operates the fuel pump. If the valves in the pump are sticky, fuel will not flow to the carb very fast. If it were my issue, I would start by verifying fuel flow to the carb when it is failing. Just pop off the fuel line at the carb, and fuel should flow. If not, the issue is upstream of the carb. If there is fuel flowing, yet no gas in the carb, the issue is at the carb. Either way cleaning every bit of the fuel system, and verifying fuel flow is going to help a lot.