5hp tohatsu 2T starts but will not run.

[limey01]

This has been a good engine, used only 10-15 hrs per season for the last 8 yrs. All has been well but mounted it on my alum rowboat with fresh fuel/2T mix and it would start then not run. I'd pull it several times and no action, then wait a bit and it would start but die within 30 secs. Sounds like fuel starvation, so I took off the carb and verified that there's plenty of fuel available from the tank to the carb inlet. Carb actually looked very clean - no visible silt/debris and I blew out all the orifices I could find. Put it back together and same problem - fired right up and quit 20 secs later. The carb looked pretty simple so not sure where to go from here - any pointers appreciated...

 

[pvanv]

Re: 5hp tohatsu 2T starts but will not run.

Start with the basics... Fuel, ignition, mechanical... Disassemble and soak the carb in dip, check plug condition (if dry, no fuel). Sounds like a possible varnished low-speed circuit in the carb.

 

[Wee Hooker]

Re: 5hp tohatsu 2T starts but will not run.

Does sound like fuel starvation. That means: a) bad fuel pump b) clogged /sticking carb c) no fuel getting to either or. Having just chased a fuel issue on a 5b, I'll offer this.

1) Double check the petcock and tank vent. ( assuming internal tank) Then disconnect line at carb/fuel pump and blow into the hose to assure your filter /line isn't plugged. i.e Make sure make sure fuel is flowing right at the carb.

2) Lightly rap the side of the carb a few times with a wrench to see if your suffering from a stuck float/needle valve. If the float is stuck in the up position, it will not allow fuel into the bowl or into the carb.

3) Turn your low speed idle screw out 4 or 5 full turns ( Count!) and try running it. You might just have a bit of something restricting it that passes through with teh needle backed out. Then put it back in it's original position ( usually 1.5 turns from seated to start.)
4) Take a empty /clean spray bottle ( from windex etc) and put a cup of fuel mix in it. If your motor has an air box/cleaner/screen, remove it so you can see down the throat of the carb..
Then when the motor gets running for those 30 seconds, steadily spray fuel mix down the throat of the carb if it continues to run, your carb is not feeding it fuel.

If it is fuel starvation, and you know your good right up to the carb. You may need to rebuild your fuel pump and or carb.

( If your motor has a seperate fuel pump, you can try gravity feeding fuel right into the carb fuel port via a tank held over the motors head . this will tell you if it's the carb or FP.)
hth