Oil & Fuel Fuel tank vacuum

jbitting · Jul 27, 2003

I have a YM1500. Plastic fuel tank, fuel line out the bottom. There is another (small) line going into the tank by the cap. I thought it was a vent until I saw it was coming from the injectors... what is this little line for?... meanwhile, my fuel tank is pulling a vacuum and trying to crush itself.
1. should the small line be coming from the injectors and what is it?
2. how do I get around the tank vacuum?
I'm sure one of the Yanmar vets has seen this before.
any help appreciated.
Thanks,
Jake

MarkStewart · Jul 27, 2003

Maybe it's the supply line for the thermostart reservoir.

pruntyc · Jul 27, 2003

I believe he is speaking of what the manual calls a bleed off line, that runs from the injectors to the tank.

kayssupply · Jul 27, 2003

The line is for unused fuel returned to the tank. I had a YM1401 do the same thing with the tank. I had put the wrong cap on it. The cap must have a vent. I had actually put a new gasket on the cap and it was too soft and closed the vent notch in the cap threads.

Inspector507 · Jul 27, 2003

Jake,
My YM1700 did that a few times if I tightened the cap too tight. If I put it on enough to not vibrate loose, all was well with the tank.
Hope this helps

jbitting · Jul 28, 2003

Roger that fellas...
Thanks for the replies...

will check the cap/gasket and make sure all is well with the vent notch.

I have been known to overtighten a cap now and then too <grin>

appreciate the replies.
Thnx much,
Jake

shady1701 · Jul 28, 2003

if you check and can't find vent run engine with fuel cap slightly loose the pumps on the engine draws a vacum just like old fuel pumps on gas so if tank ain't vented it will pull vacum on it's self..