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Tohatsu 20hp problems

C

chrisfehilly

New member
Hi everyone,

I have a 2020 tohatsu 20hp efi with 40 hours, always ran great, today I ran it for maybe 10 mins to my first fishing spot, killed it fished for a while, went to start it again and it started in a cloud of smoke and a slick of oil on the surface, I came home on my trolling motor, let the engine cool down and checked the oil, it smells of fuel and has risen above the fill mark on the dipstick.
What could be causing fuel to get into the oil on such an engine with such low hours?
 
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Not sure on this one, new to me.....but if the fuel tank had excessive pressure from a no vent situation and out in the hot sun, perhaps it had something to do with the fuel passing into the oil. Many plastic tanks have inadequate venting systems...self operating venting is proof positive on these. Question is, how can fuel pass by the injectors, unless one of them failed? Do you use pure petrol, or 5 to 10 percent ethanol fuel?
 
You could have a blown diaphragm in the low pressure fuel pump. You can check by pulling the pump and priming. If you see fuel around the push rod, the pump is leaking. Time for an oil and filter change. Of course, you always disconnect the fuel at the motor when not running (overnight) right? You are in warranty. See your dealer.
 
pvanv said:
You could have a blown diaphragm in the low pressure fuel pump. You can check by pulling the pump and priming. If you see fuel around the push rod, the pump is leaking. Time for an oil and filter change. Of course, you always disconnect the fuel at the motor when not running (overnight) right? You are in warranty. See your dealer.
Click to expand...

I think it is the low pressure fuel pump like you said. Its back with the dealer now anyway. I always disconnected the fuel line overnight and followed the break in procedure to the letter. Just a fault in the fuel pump or possibly something else? I'd like to know the cause so it doesn't happen again.
 
Your dealer can test and let you know. These can fail, especially with the new EPA tanks if left connected as the tank pressure can get high in the sun. I have only ever seen one fail under non EPA tank situations in 20 years of turning wrenches on Tohatsu motors.
 
So Paul, the low pressure pump gets its pulses from a mechanical drive? Just curious. I simply don't have information on these. Why would they allow the dry side of the diaphragm to relieve itself into the crankcase? Sounds like the fuel pump on our 1949 Chevy truck.
 
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Thanks Paul....I think you nailed the problem here. Musta been a defective pump. Or excessive tank pressure.....or both.
 
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