2008 yamaha nytro lean afr

[Nytroed]

You have to determine how that external screeching in-line pump is getting fed. Gotta find out if there is a restriction on the supply side, like it's trying to draw fuel thru the old remnant in-tank pump & sending unit which would be very very bad. Hopefully someone deleted the in-tank sending unit and replaced it with some sort of rigged-up low restriction fuel pickup, doubtful though if the last owner was dumb enough to beat on the clutch with a hammer...

That's for True chief! I can't believe how much stuff was rigged up and wrong with this sled. Can't wait to take it out and see how it's going to run for the first time.

 

[Nytroed]

You have to determine how that external screeching in-line pump is getting fed. Gotta find out if there is a restriction on the supply side, like it's trying to draw fuel thru the old remnant in-tank pump & sending unit which would be very very bad. Hopefully someone deleted the in-tank sending unit and replaced it with some sort of rigged-up low restriction fuel pickup, doubtful though if the last owner was dumb enough to beat on the clutch with a hammer...

Yessir so if you kink the hose coming from the inline pump it sounds like its pumping air

 

[Nytroed]

Fuel pressure gauge will tell the tale now.
No, old fuel will not create that lean of an AFR. It will cause misfires but you'd hear that.
I'd dump it though unless it's less that 30 days old.

Take the fuel cap off, look down inside the tank for a plastic sending unit that will have a pump inside. Search this forum, there are threads with pic's of in-tank sending units.

Sun of a gun I found the problem. They were actually smart enough to remove the pump from inside the tank but they used regular fuel like it ate it and somehow collapsed and had a hole through the middle about the size of a jet. Hoping that burn down my motor. But I will need to figure out what kind of filter sock and stuff I need. It looked like they used the original sock but it's pretty dirty. Do I need to use a different one? I will get actual submersible line to fix that part.

 

[mbarryracing]

Pre-Pump filter should be course 70-100 micron. Post-pump filter fine 10 micron.
The stock cloth in-tank pickup socks I think are too fine and create too much of a restriction for a high volume pump. You need something mesh...
I use Walbro MP12 and MP13 fuel pickups.