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Discussion Starter · #1 · (Edited)
1998 ZX11...everytime my tank gets to the empty mark...[i still have 2 gallons left]....the carbs go to hell.....the idle drops to 750 and starts to drop and stall......stoplights are a nightmare and it makes a horrible sound in the exhaust......this has been going on for a month and 1/2.....
i fill at different stations everytime....
it usually goes away after 20 miles of riding after i fill back up
i ve had many encounters with ethanol..but nothing where the bottom of the tank triggers it....
[10% ethanol in so oregon here]
my tank is locked...but i was thinking maybe someone put something in it [ i doubt seriously]
any ideas would be great....thanks
 

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So, one of two things is happening here, you are running out of gas and need to switch to reserve.

Or your fuel pump doesn't work and the tank is gravity feeding the carbs until it gets too low to do so. This happened to my 7 when I bought it. Thankfully my fuel pump was just "stuck".

I would check to be sure the fuel pump is functional. Surely 11s have fuel pumps don't they? I know my 7, and I had this issue. May not even be related to your problem at all.
 

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Discussion Starter · #4 ·
i have a filter ...so i dont believe its rust/dirt....but that fuel pump idea might make sense...even though it has nearly 2 gallons when this starts....ive done the switch to reserve with no change.....
 

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Are you switching from ON to REServe exactly depending on how much fuel is in the tank: so if it's full it's ON and if it's at 2 gallons its on REServe?

Try leaving it set to REServe after you fill up. Sounds like there's water or rust collected at the bottom of your tank. A 100 miles of riding a full tank on REServe should drain most, if not all of it out.
 

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Back to e1's question, does it run fine when full with the petcock in Reserve? Could be the metal line inside the tank for the reserve circuit is plugged. If not, about 2 to 2-1/2 gallons is where the tank will stop gravity feeding. Remember, the petcock is above the bottom of the tank, once the fuel level is below the petcock, it won't move out of the tank without the pump.

It could be a pinhole in the fuel line. With the fuel level above the petcock the natural flow of the tank keeps air out of the line, when below, the suction of the fuel pump can pull bubbles into the line causing the carb problems.

Best of luck!
 

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I agree with Squidge on the fuel pump theory and its easy enough to check if the pump is working and take a fuel sample at the same time.
 

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Had a similar issue that occurred ONCE, just recently, and hasnt happened since...

Near reserve, hit the freeway, grabbed a few gears, and she started to bog, loosing a cylinder. By the time I switched to reserve and exited the freeway, the issue was gone and I have been running on full petcock and reserve with no further issues.

When I got home I dumped about 4 ounces of Sea Foam in the tank just for good measure. Im definitely aware of the age and miles on the fuel pump, but in my experience they either work or do not....

Also, a bit of shit on the petcock screen could cause a short term fuel starvation, especially under heavy throttle... OR, a pinched fuel tank air tube, causing a momentary vacuum lock.

Sea Foam is cheap, run a full bottle thru about 3 tanks and see what occurs....
 

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Discussion Starter · #9 ·
yes...ive had the problem on a low tank in the on and reserve.....and it runs fine at full in reserve and on.....but if like you said...it stops gravity feed in reserve or low...that sure would sound like my gremlin....now ive seen on other threads that the pump only runs at start up?..if so i should test only at that point??
 

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Discussion Starter · #10 ·
also it says on the tank sticker that it conforms to CALIFORNIA standards...in my experience [ive had over 40 bikes in my life]..and that emissions is usually a vapor canister and suction valve that doesnt hurt anything but this bike has always been rock solid so i havent gotten into her just yet to see for myself......is any possibility of a smog part jamming me up??
 

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yes...ive had the problem on a low tank in the on and reserve.....and it runs fine at full in reserve and on.....but if like you said...it stops gravity feed in reserve or low...that sure would sound like my gremlin....now ive seen on other threads that the pump only runs at start up?..if so i should test only at that point??
the fuel pump works during cranking and engine running.I would run a hose from a gas can on the floor to the inlet of the filter.If the pump is working the pump should draw the fuel up from the can and run the engine.
 

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Discussion Starter · #15 ·
ok , so i took the seat off and was looking for the pump relay and got a shot of gas to the face:rant and saw the fuel line coming from the selector to the pump was split and gushing....i went ahead and pulled the tank off since it did half the work for me....still couldnt find the relay so i disconnected the "Y" going to the carbs and cranked the engine ....and it gushed out nicely.........so im thinking at this point that the split in the fuel line was sucking air....which would only effect the pump.....this could explain alot...but ill drive it down to reserve this week and test the theory.....thanks again...ill get back with the results in a week or so....
 

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Discussion Starter · #17 ·
well....:tard i thought id fixed it...but something else just cropped up....i took it for test ride and its running like crap.....it smells rich and is bogging,coughing and hiccuping....all i did was replace the line from the petcock to the filter....and when i tested the pump..it may have sucked air in...but 25 miles later its still going on.....it seems related to what ive done.....oh ...almost forgot..i put a 1/2 can of seafoam in the FULL tank...ive seen people put too much marvel mystery oil in a tank and mess it up pretty good...but im puzzled on this one... i also connected the emission lines back up coming off the tank...i checked for gas around them and they're dry and gas free...so i doubt thats the issue....another thing that may be related or not is the fuel filter...its the common type you can find at NAPA etc....its cylindrical,glass with chrome ends and screws together with a replaceable white screen...it may not filter the really tiny stuff..i dont know ...id need the specs on what the micron limit is for these carbs...any help appreciated ....
 

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Discussion Starter · #18 ·
i drained the gas out last nite and filled with my extra 5gal jug....this morning i went out for a test and its still crap....i looked online about seafoam problems and "whata u know?!?!".....i found about 17 auto/truck/cycle forums that had the same reaction to the stuff....it seems it can ruin a set of sparkplugs in 10 seconds...so ill be pulling the plugs next with my fingers crossed:banghead
 

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!/2 a can is WAY to much Sea Foam....


Been running it for years, and NEVER had issues with it destroying plugs...
 

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Discussion Starter · #20 ·
i pulled the plugs and they ok... but the gas turned to swamp water[ brown soup]....i drained the tank and refilled...but its still funky....i might drain another tank and hope it starts coming around ....what a mess!:angry.....one ounce should be plenty next time
 
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