2002 Yamaha 2-stroke won't stay running..?

[exmoore1]

Here is the condensed story:
A few days ago I went to run my boat. Been in the barn for about 2 months.
Idled rough. When I gave gas, would start to go, but then would not get up on plane-kind of bogged down. Would not get up to speed. Would cut off at idle, but restarted fine.

Two days later, never left the dock. Idled ok, but as soon as I put it in gear, would cut off. Never got good pressure in bulb.

Here is what I did:

Replaced below deck fuel lines from bulb to pickup tube on tank. Replaced bulb, anti-siphon valve, fuel pump, quick connect at cowling. Installed brand new water-fuel separator. Removed Yamaha fuel filter and connected line directly to new fuel pump (since I installed fuel-water separator).

Primed fuel lines with bulb, ran great in driveway for about 10 seconds (I guess until fuel in bowls burned up) then died. Now wont stay running.

Pulled new fuel filter off and poured gas into glass jar twice - no water.

Running out of ideas. If I disconnect fuel line on carb. side of fuel pump, I have no problem squeezing bulb and have fuel shoot out of fuel pump.

I don't think it's a carb. issue, since it runs when I take it all apart and put,it back together and prime everything...

Today, I plan to disconnect fuel line on carb side of fuel pump and turn it over to verify that new fuel pump is working correctly.

Also thinking about sticking fuel line fuel tank side of bulb into a gas can with new gas to see if it runs.


Any ideas? What am I missing?

Thank you so much.

Erik

[99yam40]

monitor fuel pressure and vacuum to see if there is a problem

[exmoore1]

Thank you. Not sure how to do that, but I will look it up.

It's my understanding that there is no vacuum pump, but rather, that the vacuum on the fuel pump comes from the pressure created by the movement of the piston..is that correct?

Erik

[99yam40]

I was meaning the vacuum on the suction side of fuel pump, it should show if there is a restriction limiting fuel flow from tank area

[exmoore1]

Thanks.
Ran from a remote tank last night with new gas - ran perfect.
Then siphoned 5 gallons of the gas out of the boat and put it in another external tank and it rank rough and cut off a few times.
Color is darker - does not smell quite as strong.
Might be bad gas.
Gonna run it on the river today on an external gas can and see what it does under load.
AT LEAST, it's not the carbs!!

Erik

[BQUICK]

I had a similar issue...had to dump 40 gallons of fuel. Tried adding fresh to it, additives, ran through a Racor funnel. Ethanol gas had turned to crap.....

Every bit had to be removed from the tank and the filters replaced again.

[exmoore1]

Ran it on the river yesterday. Ran pefect on new gas from external tank. Ran 'ok' on the five gallons of gas i siponed out of boat tank and ran from external tank. Cut off at idle - restarted easily. Almost convinced the gas is just starting to go 'bad.' Won't be totally convinced until I drain ALL of the gas out and refill the tank.