Tohatsu 6hp 4 stroke keeps stopping

M

Mandarin331

Well-Known Member
Joined
27 Oct 2008
Messages
791
Location
North Norfolk
Visit site
Hoping someone can help. We have a 2020 Tohatsu 6hp outboard that runs perfectly, until it stops, sometime after 10 mins sometime 40. We've tracked it down to fuel shortage, when it stops we can see that the filter is empty.

Question is why should the.pump suddenly decide not to pump (it runs from an external tank, also brand new with fresh fuel).

The engine has been in store since bought, run once by the previous owner about a year ago and not again until now, so essentially a brand new engine, although it could have had fuel in the system for year.
 
Mandarin331 said:
Hoping someone can help. We have a 2020 Tohatsu 6hp outboard that runs perfectly, until it stops, sometime after 10 mins sometime 40. We've tracked it down to fuel shortage, when it stops we can see that the filter is empty.

Question is why should the.pump suddenly decide not to pump (it runs from an external tank, also brand new with fresh fuel).

The engine has been in store since bought, run once by the previous owner about a year ago and not again until now, so essentially a brand new engine, although it could have had fuel in the system for year.
Click to expand...
Tank vent open and venting properly? .... Try running with the cap off

Air leaking into the fuel line? Connector is no 1 suspect for this.

Defective fuel pump? Tried pumping the fuel line primer bulb ? Will that keep it running

Will it run from the integral tank Change over cock OK ? Or are you saying it will not run from integral tank but will run from remote tank?
 
Mandarin331 said:
Hoping someone can help. We have a 2020 Tohatsu 6hp outboard that runs perfectly, until it stops, sometime after 10 mins sometime 40. We've tracked it down to fuel shortage, when it stops we can see that the filter is empty.

Question is why should the.pump suddenly decide not to pump (it runs from an external tank, also brand new with fresh fuel).

The engine has been in store since bought, run once by the previous owner about a year ago and not again until now, so essentially a brand new engine, although it could have had fuel in the system for year.
Click to expand...
Check if that year model has a filter in the tank isolation valve. Ours did. It was full of dog hairs ?
 
VicS said:
Tank vent open and venting properly? .... Try running with the cap off

Air leaking into the fuel line? Connector is no 1 suspect for this.

Defective fuel pump? Tried pumping the fuel line primer bulb ? Will that keep it running

Will it run from the integral tank Change over cock OK ? Or are you saying it will not run from integral tank but will run from remote tank?
Click to expand...
Thanks for the inpu, much appreciated.

Tank vent is open and working g OK

I will check the connectors, hopefully OK as they're a brand new.

Yes, pumping with the primer bulb keeps it running. My suspicion is the pump, but why when it first did it after 45 minutes of running since new?

It has no internal tank, just the remote.
 
Mandarin331 said:
Thanks for the inpu, much appreciated.
Tank vent is open and working g OK
I will check the connectors, hopefully OK as they're a brand new.
Yes, pumping with the primer bulb keeps it running. My suspicion is the pump, but why when it first did it after 45 minutes of running since new?
It has no internal tank, just the remote.
Click to expand...

If pumping the bulb keeps it going it is either air getting into the fuel line or a defective pump.

If you see the filter is full of air it suggests air getting in is the culprit!

Focus your attention on the fuel line connectors and other joints

( BTW there is a filter on the fuel pick up in the tank)
 
VicS said:
If pumping the bulb keeps it going it is either air getting into the fuel line or a defective pump.
If you see the filter is full of air it suggests air getting in is the culprit!
Focus your attention on the fuel line connectors and other joints
( BTW there is a filter on the fuel pick up in the tank)
Click to expand...

I agree, most likely drawing air on the fuel line somewhere, check hose clamps and tails are tight on the bulb.
 
geem said:
Strip the carb and clean the jets. I had to do this a couple of times on mine. 4 strokes are far less tolerant of dirt or poor fuel than 2 strokes
Click to expand...
This. And double check the fuel line and tank. There’s nothing quite like a quick runup and a 2 year layup for turning fuel into something resembling ghostbusters slime, but dogshite brown in colour. Any of that in any part of the fuel system and you are up the creek. Hopefully with a paddle cos you’ll be needing it.
 
We experienced the same issue with the same engine and it turned out to be less than perfect hose clamps on the fuel line. Pumping the fuel bulb when it started to falter keep it running. We actually pressure tested the hoses using a bike pump and soapy water.
Chris
 
geem said:
Strip the carb and clean the jets. I had to do this a couple of times on mine. 4 strokes are far less tolerant of dirt or poor fuel than 2 strokes
Click to expand...
If there is a problem with the carb it is not likely to run for 40 minutes or to keep running while the bulb is being pumped.
 
I have 2 tohatsu 6hp, one 2 years old and i guess 5 hours, the other a month old and an hour in, but with the inbuilt and external tank. Both start 2nd pull every time, and run 100% as i turn off the fuel and run them dry every time i use them. However, i have had problems with the external fuel line in both. If i squeeze the bulb enough to prime the engine its fine, but if i really squeeze it hard i found a number of fuel leaks. The metal bandit clips leaked, the bulbs perished and the fuel was a bright yellow colour, due i think to impurities in the new fuel lines disolving in to the fuel - or the new e fuel related problems. I replaced all the bandit clips with double cable ties, rinsed out the lines with fresh fuel, just pumped it till clear and both engines run perfectly now. I fow also disconnect the fuel lines and clear them through now, as best i can, by pushing in the BB and pumping the line semi clear. So far so good and now both run exactly as i would hope
 
VicS said:
If there is a problem with the carb it is not likely to run for 40 minutes or to keep running while the bulb is being pumped.
Click to expand...
My 2 stroke did. It is possible. Of course an air leak is also possible. It’s the lay up that makes me think a fuel jelly in the carb problem is likely, outboards hate not being used.
 
OK, so we cleared out the fuel system, dumped the supermarket fuel, stripped the carburettor (some varnish on the bottom) and soaked in carb cleaner.

Reassembled with fresh BP super 5% and its runs perfectly now.

The dealer strongly advised against supermarket 10%.

No clear findings but it seems to be solved so I'm happy.
 
You must log in or register to reply here.

Share this page

Top