Fueling problem. After sitting, fuel hoses dry, won't refill

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Fueling problem. After sitting, fuel hoses dry, won't refill

Postby GreenMagicMan » Thu May 25, 2017 2:08 pm

Hi all:

Very recently figured out a problem and the symptoms but not the exact cause per se.

I've had off and on start / no start problems with Green Magic. The key here is how long it's been sitting. Used to be 1-2 months was an issue, now that gap seems smaller. Sometimes 1-2 weeks is enough for it to not want to start.

Several years back I would finger the carbs getting plugged up again with ethanol gunk and yank them again and clean them. The 2nd or 3rd cleaning I really got every single hole cleaned out including the starter air jets (not pilot air jets). I did not even know the carbs had this.

Anyway, after that starting was a breeze. And then... it slowly got worse.
Recently the bike sat since December without being started. Fast forward to May 2017 and it would not start (battery strong - I checked it 12.7 - 13 VDC). I rode it a mile down a steep hill. All of 2016 that would do it and it would start after 1-2 bump start tries. This time nothing after 15 + bumps - as many as I could. It never ignited a cylinder or got close to firing. Starter works, engine cranks. No turn over with button or push starting it ins 2nd or 3rd gear.

What my friend and I figured out this time around was there was ultimately no fuel in the system. Went to drain the carbs of 'bad fuel' and very little came out. Odd.
The petcock works properly in all 3 settings, and when attached to the clear tube to the fuel filter and pump the fuel won't leave the tank and go into the fuel hose there (it will gush out with gravity if the petcock is opened to atmosphere).
Pulled the tank and I have clear fuel hose from the tank to fuel filter and fuel pump to carbs. I didn't notice it immediately, but the tubes were empty of fuel and dry.
What I did see is the fuel pump was wet with fuel around it. And I did not have several hose clamps installed over the fuel hoses. So I *think* that the fuel is slowly dripping out of a hose connection as it sits over time all the fuel leaves that low spot in the system.
We removed the fuel pump and my friend blew what tiny amount of fuel was left down there from one side of the pump to the other through the hoses.
We poured fuel manually into the hose from the tank. Then we cranked the bike and the fuel didn't move. My friend put his thumb over the tube opening and said he could feel suction.
We then attached the hose back to the petcock and the bike almost instantly fired up and ran!

So big question: why?
-Shouldn't a setup empty of fuel prime itself?

-Is the pump failing?
-Is there some sort of reverse vacuum pressure on the fuel lines to the petcock that prevent fuel from going in?
-Does it just take a really really long time to prime an empty system? I mean, a really long time?
User avatar
GreenMagicMan
Track Racer
 
Posts: 631
Joined: Wed Oct 09, 2013 3:51 pm
Location: USA
Geographic Location: California and NH
My Bike Make: 1995 ZX6e
Engine Size: 600
Model: ZX6E / ZZR600 E3

Re: Fueling problem. After sitting, fuel hoses dry, won't re

Postby GreenMagicMan » Thu May 25, 2017 2:10 pm

Been searching around here to see how the fuel pump operates and how it behaves failing without much luck.
Of course, at this point I have a number of cosmetic repairs needed now to GM and also a new stator cover needed after my recent crash.
But darn, GM was running so well again!
User avatar
GreenMagicMan
Track Racer
 
Posts: 631
Joined: Wed Oct 09, 2013 3:51 pm
Location: USA
Geographic Location: California and NH
My Bike Make: 1995 ZX6e
Engine Size: 600
Model: ZX6E / ZZR600 E3

Re: Fueling problem. After sitting, fuel hoses dry, won't re

Postby GreenMagicMan » Tue Aug 07, 2018 9:40 pm

well this was a shocker.
After the bike sat in out of the elements storage for 14 months it fired right up - on the original 6 year old AGM battery no less - after simply charging battery overnight.
Go figure, I sure can't.
I was trying to explain to my impatient friend after work: "Dude! You don't know this bike! It will not start after sitting 2-3 months! It will be nothing but drama and about 1000% you can be sure demanding a full carb clean...blah blah blah..." and then it fired up almost instantly.
I don't know what's going on (but I like it). I'm in Krazyland...

(only clue I have before going full on crazy was my friend said he put Stabil in the gas tank - but did not run the engine after my crash. I've never added Stabil on my numerous stints away from the bike).
User avatar
GreenMagicMan
Track Racer
 
Posts: 631
Joined: Wed Oct 09, 2013 3:51 pm
Location: USA
Geographic Location: California and NH
My Bike Make: 1995 ZX6e
Engine Size: 600
Model: ZX6E / ZZR600 E3


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