Help...leaking gas

[apsolus]

gravity would help fuel bypass the pump. id say appearantly it does cause if it didnt our man here wouldnt have a gallon of fuel on the ground

[DonTZ125]

FZR's have fuel pump do they not? If the petcock was open and it drained the tank thro the carbs why does the bike need a pump ? Just asking .........................

for when the gas tank is half full or so when the gas line is below the float bowls

On my bike the pump primes itself every start up (as does everyone elses ) is that just a precaution ? Are there in fact two routes for gas into the carbs..............................

The pump primes itself until the back pressure (against the float valves) reaches the cut-off point. There is one fuel route to the carbs (via the pump) from the petcock; there are two hoses to the petcock (ON and RES). To expand on what Racerd said, on some models you can't empty the tank by gravity, but a full tank will quite cheerfully flood into your crankcase.

The petcock as a positive shut-off device; the float valves are more for flow control. They CAN achieve tight shut-off, but are far more prone to leaking (they wear much faster, and are much more vulnerable to a bit of crud). Given the potentially devastating effect (and expense) of fuel getting into the engine oil, I would have thought that George would be banging the petcock drum as loudly as I sometimes do.

It really could be thought of as the fuel version of the Overload Interrupter that I'm working on for the TCI...

[racerd14666]

[/quote]

On my bike the pump primes itself every start up (as does everyone elses ) is that just a precaution ? Are there in fact two routes for gas into the carbs..............................[/quote]


nope only one, the fuel pump when not running blocks the fuel from flowing some what it depends on how full your tank is if my tank is full it takes a few click to prime its its almost empty it takes a bit more. but its only 0.95 psi

i dont understand all this half ass theory's to you gotta shut ur petcock off cus your needle and seats cant stop the flow of gas but there for flow control. all 13 something bikes i have owned i only had to shut the petcock of on 1 bike cus i didn't feel like replacing the needle and seats. every one says oh there for "flow control" yes they are, they STOP the flow of fuel the more fuel in there the harder they seal its that simple, idk if you ever cut one apart and measured the sealing surface size and angle but it equates to almost 20 psi of sealing force on most, and if the work properly you dont have to shut off the petcock cus last time i checked 20psi is more that 14.7psi thus over coming gravity and stoping the flow. and like on my r1 its under the seat in a hard to reach place cus you really dont need it and on my 2 fzrs that i have i dont touch the petcock unless im flipping to reserve to burn the bottom stale-ish gas or if im removing the tank. you cant make up excuse for the needle and seats not working like there dirty or there prone to wear, hey that just means your to lazy to clean the car cus your bike probly runs like crap to begin with or to lazy to replace your worn out parts because i would bet my professional reputation and a thousand bucks if the needle and seats work properly they wont leak PERIOD. idk maybe im weird for thinking with logic.......

[DonTZ125]

Racerd - your comments are approaching ad hominem, and I would greatly appreciate it if you would temper them. If you actually read what I said -

They CAN achieve tight shut-off, but are far more prone to leaking (they wear much faster, and are much more vulnerable to a bit of crud).

Sounds awful damn close to your comment of "if the needle and seats work properly they wont leak PERIOD", right?

As a matter of fact, I'm not sure you read what YOU wrote - "i only had to shut the petcock of on 1 bike cus i didn't feel like replacing the needle and seats", followed by "that just means your to lazy to clean the car cus your bike probly runs like crap to begin with or to lazy to replace your worn out parts."

Sort yourself out.

[yamaha_george]

gravity would help fuel bypass the pump. id say appearantly it does cause if it didnt our man here wouldnt have a gallon of fuel on the ground

then you will agree with me that there are THREE possible faults to look at.

A} Petcock is leaking (if he did not put it in shut position )
B} The Pump is worn and passing fuel when not powered
C} the carb float needles are not working to spec

I was by playing "devils Advocate" trying to get the reader to think of what actually happens in the fuel line from Tank to engine.

Racer RD is spot on, My 50 years of owning & riding bikes has shown me that the fuel cock is for going from full to reserve.

The first thing I do is to take the pet cock off the tank when i get a new (to me) bike in my stable (current ownership is 9 , lost count of how many I have owned in the 50 years since I started this obsession).

I check that the reserve tube is actually there, been caught too many times by that one and that the filters in the tank are clean. Flush the tank & re-assemble after replacing the fuel switch seal if one is required, some just rely on a with taper with holes !!!!!!

The second port of call for the pre-1st ride check is the carbs ,float level & float needle seats .

You guys are very lucky you have all sorts of fancy fuel proof rubber tips , back in the day it was metal on metal and re-surfacing the needle with hand tools was a bitch if you could not obtain a spare. It was so bad I modified a pin vice and mounted it two tiny bearings on a modified dial indicator post and some extremely fine flour paper.

[DonTZ125]

Racer RD is spot on, My 50 years of owning & riding bikes has shown me that the fuel cock is for going from full to reserve.

... and yet the last time we had this discussion you agreed with me, and applauded the rant ...
viewtopic.php?f=2&t=6169#p61043

[yamaha_george]

Racer RD is spot on, My 50 years of owning & riding bikes has shown me that the fuel cock is for going from full to reserve.

... and yet the last time we had this discussion you agreed with me, and applauded the rant ...
viewtopic.php?f=2&t=6169#p61043

I surely did

BUT this time I had more time on my hands being out of hospital & not having to sneak using the laptop without the nursing gestapo catching me & no head full of pain killers either

[DonTZ125]

So whattaya saying - you have to be on drugs to agree with me?!

[yamaha_george]

Don,
It means that for a shortness of answer as time was tight where i was I agreed it stops the symptons of gas pools occurring. I.E. short term solution

However it does not cure the problem of the float needle seating which is the real hassle if the bike pisses gas.
e.g. the long term solution.

[thatkid]

I'm with Don here, the fuel pump has 2 one way valves. The inlet valve which allows fuel in but not out, then we have the outlet valve which allows fuel out but not in, IF the petcock is ON, a sticky float needle will flood the cylinder (gravity/syphon effect) period...

[yamaha_george]

I'm with Don here, the fuel pump has 2 one way valves. The inlet valve which allows fuel in but not out, then we have the outlet valve which allows fuel out but not in, IF the petcock is ON, a sticky float needle will flood the cylinder (gravity/syphon effect) period...

So, my "devils advocate position" that there is more than one area to be investigated stands