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Air bubbles in fuel line FL350, bad tee check valve
http://www.pilotodyssey.com/PO/viewtopic.php?f=111&t=4311
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Author:  stix [ Mon Jun 02, 2008 1:56 am ]
Post subject:  Air bubbles in fuel line FL350, bad tee check valve

Before going out to the dunes this summer I relaced all fuel lines, fuel pump and fuel filter. I am running the Mikuni fuel pump and stock Honda fuel filter. The fuel line from pump to carb is clear blue so I can see the fuel. This past weekend while at Little Sahara, we fueled up the Odyssey, took it out on the dunes and ran through about a 1/4 tank of gas, then after running in the trails the motor (( Internal Combustion Engine ? )) just quit, almost like I accidentally hit the motor (( Internal Combustion Engine ? )) kill button. So at that time I checked the clear blue fuel line(running from pump to carb) to see if it was getting fuel, it was dry. I then cranked the Engine an then fuel began to flow and motor (( Internal Combustion Engine ? )) fired up, I let idle for a minute to make sure fuel was still flowing, fuel line was full and seemed to be ok. We began to head back to camp to investigate problem further so I buckled up and took off, got to mid throttle and the motor (( Internal Combustion Engine ? )) started to lose power, so I stopped, motor (( Internal Combustion Engine ? )) still running, and noticed small to large bubbles flowing from the pump to carb. So we limped back to camp, bubbles still in fuel line, also noticed some times large bubbles. Weed was there and he thought maybe the fuel line in the gas tank had cracked and was sucking air. So I ran the Ody in reserve and still had the bubbles. I then tightened most of the hose clamps on most of the fuel lines that I was able to get to at the time thinking I was pulling in air but wouldn't I be leaking fuel too?. I removed the vaccum line into the pump and made sure I had vaccum pulses when I cranked motor (( Internal Combustion Engine ? )), maybe weak pulses from cracked vaccum line or loose connection? I disconnected the hose that runs from the check valve(tee) to the tank, cranked the motor (( Internal Combustion Engine ? )) and some fuel was spurting from the check valve,I thought this check valve was to let fuel back into the tank when carb bowl and fuel line to carb was full? Well we had to pit the Odyssey cause I didnt want to damage Engine running fuel line dry. I havnt had a chance to investigate further but my next thing to do wil be just switch out the pump with one that is confirmed working.What else am I missing? Thanks.

Author:  hoser [ Mon Jun 02, 2008 4:12 am ]
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Gas lines are run too close to a heat source and the gas is flashing to a vapor ? They on summer blends yet I think part of the summer blend is to make it where it don't evaporate as much .

Author:  bugeye59 [ Mon Jun 02, 2008 6:45 am ]
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You could possibly have a small hole in your Fuel Pump Diaphragm....Baz

Author:  bugeye59 [ Mon Jun 02, 2008 6:51 am ]
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Sorry,I just reread your post,and you say you have new fuel pump. I am on my 5th Grappa n Coke.

Author:  brooks [ Mon Jun 02, 2008 9:49 am ]
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hoser wrote:
Gas lines are run too close to a heat source and the gas is flashing to a vapor ? They on summer blends yet I think part of the summer blend is to make it where it don't evaporate as much .



Nope....this sounds suspiciously like what I had going on with mine when I first picked it up....low on gas, ody would run like crap then die...We didn't fill it up all the way because who wants to remove a full gas tank if it's the motor (( Internal Combustion Engine ? )), right?

Long story short...I had small rust holes in my pickup tube and the fuel pump was sucking some fuel and some gas...

Maybe your pickup tube broke off entirely. Mine ended up breaking in half, so the tank was worthless with about 1/2 tank of fuel.

You can test by filling the tank up more and seeing if that problem goes away. Hope that helps or gives you some ideas.

Brooks

Author:  stix [ Mon Jun 02, 2008 2:06 pm ]
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Crown and Coke is my fav. Well it was 90+ that day, probably hotter out on the sand, and I knew the head was hot cause I could feel the heat while sitting in the seat after running the Ody pretty hard. Today I checked out the fuel line routes and found the line just out of the petcock runs within 1/4 inch of the head. So I will be rerouting that hose. Also I will visually check the tubes inside the tank, have to consult manual on that, Bugeye I set the fuel switch to reserve hoping to bypass the other pick up tube. Ill have to check the manual further on that too, thanks mates!

Author:  Lonerider [ Mon Jun 02, 2008 3:21 pm ]
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Hey Baz, what the hell is a Grandpa and Coke? :shock:

LOL...j/k

Author:  King Kx [ Mon Jun 02, 2008 5:02 pm ]
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Your eyes will not be good enough to see pin holes in the pick up tubes with them inside the tank. Put a piece of clear fuel line as close to the fuel tank as possible. Run the Engine. If you see bubbles, then you are sucking air from inside the tank.

Author:  stix [ Mon Jun 02, 2008 6:49 pm ]
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King Kx wrote:
Your eyes will not be good enough to see pin holes in the pick up tubes with them inside the tank. Put a piece of clear fuel line as close to the fuel tank as possible. Run the Engine. If you see bubbles, then you are sucking air from inside the tank.


I was wondering how i was going to see down in the tank, especially if the holes were pinhole or at the botom of the lines where I couldnt see. Thanks for the tip King

Author:  Sunblock [ Mon Jun 02, 2008 9:28 pm ]
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Let us know what you discover, I am curious on this one as well.

my 2cents... crown is best with 7up, and if your on a budget, or just cheap like me, canadian club is just about as good for half the price.

Author:  bugeye59 [ Mon Jun 02, 2008 10:23 pm ]
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Lonerider wrote:
Hey Baz, what the hell is a Grandpa and Coke? :shock:

LOL...j/k


Ha! LMAO! :-) You guy's crack me up!

Grappa is an all Alcohol type,kinda like whiskey,but made from the left overs after wine making.
It's quite strong.The one I drink,is made by one of mate's employees.He double distills his :shock:
His is very High Octane! Would kill a Cat at 20 paces :shock: and has been known to be used by one
of the guy's wives to clean the bathroom and shower tiles! :shock: No kiddin',she reckons it's the best stuff and streak free! :-)
I have even been thinkin' of mixing up a brew with my pump 98 oct for my Pilot races! Nothin' in my race rules about that one. :-) I am SO Eco-friendly! :-)

What's Crown and Coke? Canadian Club? ...Sorry about being off topic! But these are serious questions. :-) ...Baz

Author:  stix [ Mon Jun 02, 2008 11:17 pm ]
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mike25 wrote:
Let us know what you discover, I am curious on this one as well.

my 2cents... crown is best with 7up, and if your on a budget, or just cheap like me, canadian club is just about as good for half the price.


Yea Ill definately keep a log and post the outcome reguarding the bubbles. Hmm, well Im a little on the Patriotic side, I'd sure feel uncomfortable carrying aroung a bottle of CANADIAN Club however if it is just as tasty I could pour it into my Crown Royal bottle and no one would know the difference. LOL. Crown Royal is an " I just got paid" whiskey,expensive but smooth :-). IMO best mixed with Coca Cola(coke for the aussies). Crown Royal advertises on billboards on our highways that read "Ever Seen A Grown Man Cry" and there is a picture of a spilled bottle of Crown Royal, heh heh, so true though. I have shed a tear or two when I accidentally spillled, after having a few, cause its so damn expensive. Ill have to add 7up to the mix next time :-)

Author:  adnoh [ Mon Jun 02, 2008 11:18 pm ]
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If the tank was 3/4 full would the pick up suck air. If so how. just curous. Doe the manual have a flow rate check, pump it into your ratio rite cup it has a cc lable or could a vacume brake bleeder check pump for leak down or even pull fuel thu diaphram if a hole was in it or use the pressure side to pump air into pump to check for bubbles. If pump check out ok look into vapor lock thing as "H" mentioned. Man I sure hope your compression is ok, forgot it started and ran ok untill bubbles in line. Hope you get it fixed stixs.

Author:  adnoh [ Mon Jun 02, 2008 11:25 pm ]
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Stixs check the height of your line in relation to the level of fuel in tank. Once the level of the fuel mathces the fuel line height you loose pressure assist( weight of the fuel pushing down) and the pump does all the work. Ever drain a water bed or syfhane gas. Yes I had the pleasure as a kid to fill the minibike from moms car when ran out of pop bottles.

Author:  stix [ Tue Jun 03, 2008 12:25 am ]
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Funny thing is I never had the problem earlier this in the Spring, until I did the dipstick vent tube crankcase mod. Randy at O.S. mentioned my dip stick vent tube mod might be playing havoc with my vaccum. I Have several things to skeelbilly through. Will check out all my reply fixes this weekend and post results...marc

Author:  hoser [ Tue Jun 03, 2008 9:02 am ]
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stix9567 wrote:
Funny thing is I never had the problem earlier this in the Spring, until I did the dipstick vent tube crankcase mod. Randy at O.S. mentioned my dip stick vent tube mod might be playing havoc with my vaccum. I Have several things to skeelbilly through. Will check out all my reply fixes this weekend and post results...marc


The balancer case is separate from the Engine the only way it can affect your vacuum is if the crank seals are leaking. ::-:

Author:  stix [ Tue Jun 03, 2008 6:29 pm ]
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hoser wrote:
stix9567 wrote:
Funny thing is I never had the problem earlier this in the Spring, until I did the dipstick vent tube crankcase mod. Randy at O.S. mentioned my dip stick vent tube mod might be playing havoc with my vaccum. I Have several things to skeelbilly through. Will check out all my reply fixes this weekend and post results...marc


The balancer case is separate from the Engine the only way it can affect your vacuum is if the crank seals are leaking. ::-:


Oh. That makes sense.When I talked to Randy yesterday I don't think he quite understood what I was trying to convey to him. My cell phone was cutting in and out at the time of our conversation. Anyhow thanks Hoser and I have a few things to check over the weekend. Unless the lake calls my name. :-)

Author:  stix [ Thu Jul 09, 2009 11:10 pm ]
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Update.... The air bubbles in the fuel line were from a bad check valve "tee" not closing completely and therefore the fuel pump was sucking in air from the top of the tank through the bad (open) check valve. New check valve/tee installed and problem solved...

Author:  mozzy [ Fri Jul 10, 2009 12:30 pm ]
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Is that check valve really necessary?

I mean, as far as I can see it just lets air out of the line which wouldn't really make much difference as the bowl in the carby does end up with some bubbles in it anyway.

Can it be made obsolete & still run ok?

Author:  Sunblock [ Fri Jul 10, 2009 5:26 pm ]
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I think its like a pressure overflow valve. Since the gas is being actively pumped into the carb it allows for excess to be returned to the tank. If you bypassed it pressure in the fuel line would increase until most likely the float valve in the carb fails, and then the bowl would fill up and overflow constantly.

Author:  mudbogger [ Fri Jul 10, 2009 8:51 pm ]
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I have seen fellas stick a main jet in the lines as well to replace the tee fitting, hahaha.

Author:  Ody_Stable [ Fri Jul 10, 2009 9:32 pm ]
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The brand of carb doesn't make any difference, but the float valve and seat make a big difference.

If the valve and seat are in good condition the factory pieces may seal just fine, if they leak you can either replace them with new and take the chance they will seal or replace them with the size used on a gravity fed system from a similar sized Engine.

I personally prefer the Keihin's over the Mikuni's, but I'm sure everyone has a preference. A stock keihin from an ATC250R or CR250, MT250, etc. would work fine since they're all gravity fed systems.

I have done 4 FL250 gravity feed conversions and they all worked just fine with the stock FL250 carbs, valves and seats, though they were all rebuilt by me using the K & L rebuild kits (NOT to be confused with Keyster CRAP kits). The K & L kits used to come with new rubber tipped valves and seats and they've always sealed well.

All 3 of our pilots are running the stock carbs and gravity feed without a problem as well.

Author:  Ody_Stable [ Fri Jul 10, 2009 9:42 pm ]
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Mudbogger wrote:
I have seen fellas stick a main jet in the lines as well to replace the tee fitting, hahaha.


Yeah, bad idea in my opinion. That chokes the flow down, but increases the pressure and it's not progressive as the stock tee valve was designed.

Just my opinion though.........

I have never believed there was a REAL issue with the stock Tees, if there was, they wouldn't still be available and I have installed a few new ones in the last few years without any issues. One or two missing the spring, OK, a few more maybe (I have never seen one or known anyone to have the issue), but ALL of them (maybe somebody fell asleep at the spring installing point of the assembly line..)? BS in my opinion, hype to steer people to other products? I don't know, but I've only heard of ONE person making the claims and everyone else hyping it up, again BS in my opinion.

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