Gas in Airbox from Engine Breather Tube 82 1100EZ

[rgierer]

I have seen this bike and heard it run and can't begin to believe that the engine is running so poorly it is causing back pressure. Of course valve adjustments can be checked and compression run but I can not imagine these are not within normal limits.

I have some ratting old GS's that run great this one is in so much better shape than the best of mine ....

I don't know CV carbs well, mine just work.

I am useless to help my friend on this. The text book strategies don't seem to work ...I am hoping Earl or Keith might weigh in.

[KEITH KRAUSE]

Jeez! Whattsa matta you bike? Sorry. I know it's frustrating.
Very unusual that gas would exit (in such large amounts) through the crankcase breather hose. All venting would have to be blocked, resulting in a vacuum. The bike couldn't do this on its own.
I'm thinking someone took your two float bowl vent lines and connected them together or otherwise compromised the bowl venting.
If not connected together, check that they're both open and not routed poorly/kinked. You should be able to blow into them. If not, see what's blocking the venting to the float bowls. Both lines should have equal venting.

[away_man]

Thanks Keith, and thanks to Earl, who sent me some help via pm.

For anyone following the saga, here are my next steps:

1. Triple-check carb operation by trying to overflow them on the bench with the bowls installed, using the test tank. I think they'll continue to function normally.

2. Change oil and run the engine out of gas again. I want to try to start the next run with no gas still in the places it shouldn't be.

3. Double-check my float bowl vents to make sure they're clear

4. Plug petcock vacuum line and refill carb bowls (hopefully, just the bowls ) from the test tank

5. Double-check vent tubes at this point.

6. Start the bike and cross my fingers. 8-O

(I'm typing this list up for myself as much as anyone else (so I don't forget anything), so I figured I might as well post it. If anyone has any other steps I need to put in, feel free to let me know.

Unfortunately, I won't have any time to work on this until possibly Sunday evening at the earliest. I'll probably be taking a day off work on Monday to go through it again; I'll be sure and let y'all know what I come up with.

To be continued....

[KEITH KRAUSE]

Did you check to see that the two float bowl vent lines are open and routed correctly? Easy to see. Do you know what lines I'm talking about? Also, please describe ALL your hose connections. Every one of them.
I doubt another leak test on the carbs will tell you anything. Same thing with the petcock. Just plug the vacuum port at carb #2 and run petcock on prime using a properly vented reservoir while testing. In this condition, if there IS any petcock problem, it would be from no fuel at all or poor flow amount...the opposite of your apparent problem.
Only thing that can create such a vacuum and draw fuel in such amounts up through the breather, is plugging all venting at the carbs...the bowl vents. Or some kind of incorrect vacuum/fuel/vent line connections.

[away_man]

Keith, I know the lines you're referring to. I know at one point I was able to blow and suck air through both of those lines, but I don't remember if the carb was on the bike or not at that time. The vents were definitely not connected together at any point. I will double-check these just before my next test start; it's step #5 in my last post.

I'm pretty certain that my hoses were hooked up correctly the last time I tried it, with the caveat that I was using a test tank, and didn't have the petcock vacuum line plugged, which Earl says I need to do. And I believe him. (no offense to dietcokeking; sometimes I'm just a bit thick-headed until I get a second opinion!)

I've spent the last week going through manuals and every post here that deals with hoses on my carbs. Correct me if I'm wrong, but here is my understanding of how all the hoses should be set up for my 1100EZ:

1. Fuel hose (5/16, I think) from petcock to carb inlet, between 2 &3 on the airbox side of the carbs

2 & 3. Vent hoses from carb bowls, between 1-2 & 3-4. These are on the engine side.

4. Vacuum hose from petcock to nipple on #2 carb (engine side)

5. Drain hose from bottom of front secton of air box to under the bike

6. Vent hose from fuel guage relay thingy on tank opposite petcock assembly

7. Vent hose from battery to bottom of bike (unused, as I put in a sealed battery. I'm going to pull this one)

8. Hose from engine breather cover to top of front airbox (normally, but mine is going in a bucket while testing in case it pukes more gas)

I think that's it.

I'll let y'all know what I find out next, hopefully after riding my bike back home to use my computer. :mrgreen:

[earlfor]

Just in case. The vent hoses from the float bowls go to atomsphere. The open end of the hose is not connected to anything.

Earl

[KEITH KRAUSE]

Well, be sure to check that the float bowl vent lines are clear and not kinked. Test by blowing into the lines so you know air enters the bowls. You shouldn't need to blow real hard. Only problem here is that each line supplies venting to two carbs. So blowing into each line (with the carbs assembled) wouldn't positively prove all four carbs are venting well. You would have to remove all bowls and feel/hear air with your hand enter the bowl chamber. After this, you would prove all four carbs are venting.
Obviously, your engine is acting as a vacuum. Literally sucking fuel from the carb(s), into the cylinder(s) and up through the top breather. I didn't think such amounts of fuel could enter though, as you describe. But vacuum is vacuum. You have excessive vacuum.
Only way you can have excessive vacuum is if the engines venting has been compromised. Only vent points besides the carb vents, are the breather, and a vent hole in the crankcase area. My '79 1000 has an open hole on the lower left side, behind the starter/stator area. Not sure where yours is located. The hole is generally large enough to put your finger in. I don't know how yours could become blocked if the bike just sat and no one worked on it. But it's possible. Locate it and check it. Maybe someone here with a similar model knows the hole I'm talking about if you have trouble.
All I know is, based on your exact description of the leaking, your venting is gone and the engine is acting as a vacuum.
Besides the above, what else could cause this? An exhaust valve(s) always closed or nearly closed? How could that happen if the bike ran fine, was turned off and then sat?

[dietcokeking]

Is there any chance that his fuel tank is not venting, causing pressure build-up to flood the carbs when the petcock opens upon starting the engine?

[KEITH KRAUSE]

Is there any chance that his fuel tank is not venting, causing pressure build-up to flood the carbs when the petcock opens upon starting the engine?

Naw. If the tank had poor or no venting, you would have poor or no fuel flow.
Very odd what's happening with this bike. After sitting for about 6 weeks or so I can see the float valves maybe varnishing up and not sealing or some common thing like that, but that kind of thing would cause fuel to rise inside the carb and then exit out the engine side and into the crank and also exit out the filter side and down into the airbox and out the airbox drain line.
For raw fuel to go up into the top of the engine and drain out the breather line is excessive vacuum. Like it's being pumped. I just can't see anything allowing this excessive vacuum except for no venting. And there aren't that many vents to check.

[away_man]

Many thanks to Keith; that is the type of info I've been looking for. The more I looked at this, I was leaning more towards a vacuum problem, rather than a carb problem (carb problem would have been better, in that it's expected, relatively easy to troubleshoot, and fairly easy to fix).

I'm definitely working on the bike starting first thing Monday morning, and your tips about engine venting give me some confidence that I'll actually have it running by Monday evening.

Regarding the vent hole, if anyone knows where it is on the 1100EZ, I'd be happy to find out. I just remembered, after Keith mentioned "no one worked on the bike"-- I did change the oil last fall, and it could have been before this issue started, probably around the same time.

Could I have screwed something up in a process as simple as an oil change to create this issue? I didn't do anything as blatantly obvious as forget to put a filter in or anything....

[away_man]

Lessons Learned...

(First off, it's running! \\/)

So, after checking to make sure the carb vents were open (before I replaced the bowls), I decided to change the oil. I pulled the drain plug on the oil pan, and....

THREE GALLONS (roughly) of gas (with some oil in it) came out of my engine. :shock: The tank was not on the bike at this time, and had not been for a couple of weeks. I'm not just guessing at the three gallon measure; I drained my oil collector into a 5-gallon container, and it was about 2/3 full.This would explain the unusual occurence of gas pumping out of the breather; the entire engine was so gas-logged that it had nowhere else to go.

I pulled the oil filter cover (more gas drained out), put a new filter in, put clean new oil in, got the carbs installed, and she's running like a top again (after I got the idle screw set where it's supposed to be).

I put it back on the sidestand until the weekend, when I'm going to give it another oil change, for two reasons. 1. Just to make sure there's no residual gas in this batch of oil, and 2. to make sure no new gas has leaked from the tank into this oil. I went for a spin around the block, but that's as far as she goes until I know I have gas-free oil in it.

I'm guessing (hoping, actually) that all that gas got in there in the first place becuase of the bad o-rings on the needle valve seats. Not sure how I managed to get *that much* gas into the engine, but I'm guessing it was something to due with the length of time I left it sitting on the sidestand, and maybe running the throttle improperly when I was trying to start it with a bad battery.

I'll have to keep an eye on my oil for a while and make sure I don't still have a petcock problem or some other undiscovered issue, but I have my fingers crossed that I'm all ready to go, just in time for warm weather.

Thanks much to all that helped me out on this one. =D> I'm hoping this is the last post I'll have to make on this thread.

-Aaron

P.S. (miscellaneous thoughts)

1. I could have saved myself a lot of headache (and looking silly) if I had changed my "oil" to begin with, but I was trying to get this gas problem resolved before I put good oil in, so I wouldn't waste oil. I'm sure there's a lesson about "penny wise and dollar foolish" or being a cheapskate in here somewhere...

2. For those who think I'm either crazy or deaf, the engine really did sound fine for the few seconds it was running with all that gas in there, every time I started it. I'm reasonably confident that it drowned quickly enough every time I started it that it didn't cause any serious damage from lack of lubrication.

3. You woulda thought it would have hydro-locked with all that gas in there....started right up every time when the battery was charged. Go figure...?

Thanks again to all.

[Billy Ricks]

The o-rings on the float seats are one of the most often overlooked culprits with problems like this.

[dietcokeking]

I'm certain all that fuel entered the engine while you were storing the bike. Therefore, two things were occurring: 1. Fuel was seeping by the float needles; and 2. The petcock had been left on PRIME or the petcock is not working as designed.

The petcock should not flow fuel when the engine is stopped, except on PRIME. Of course, PRIME should only be used for the brief time necessary to manually fill the carb bowls with fuel, most often after carb service or if the bike had ran out of fuel. The bike should be stored with the petcock indicating ON (or RESERVE as the case may be).

You have to accept that our four float needles don't seal that well, or that reliably. However, unless things are really, really, really goofed up, float needles seeping at any expected rate aren't going to deposit gallons of raw fuel into the crankcase of a running engine (although that particular cylinder might be running rich).

An investment in a new petcock (or a cheaper rebuild kit) would eliminate this worry for you.

[earlfor]

If you didnt have a bad petcock, gas could not flow even if you removed the float needle valves and threw away the floats when the engine was not running. When the engine is running, fuel is drawn into the combustion chamber to be burned, not the crankcase. You probably do have faulty "O" ring seals on the fuel inlet valves, but it is for certain, the petock is BAD.

Earl


[QUOTE=away_man]
I'm guessing (hoping, actually) that all that gas got in there in the first place becuase of the bad o-rings on the needle valve seats. Not sure how I managed to get *that much* gas into the engine, but I'm guessing it was something to due with the length of time I left it sitting on the sidestand, and maybe running the throttle improperly when I was trying to start it with a bad battery.

I'll have to keep an eye on my oil for a while and make sure I don't still have a petcock problem or some other undiscovered issue, but I have my fingers crossed that I'm all ready to go, just in time for warm weather.

[KEITH KRAUSE]

Hope you get the gas leak fixed.
Your latest findings make sense but with that much fuel in the motor, I don't see how gas was only noticable coming from the crankcase breather line. There should also have been fuel passing into the exhaust and dripping through the condensation holes at the bottom of the exhaust, and more would be backing out of the overflow tubes for the carbs. With the fuel ONLY leaking from the breather, it was quite a head scratcher.
Maybe you didn't notice fuel exiting at these other places but I have to believe it was after your latest description. That would have made it easier to figure out that your motor was simply filled to the maximum. Not a vacuum or venting problem, just simply too much fuel entered, due to a float valve(s) or bad petcock.
Any float valve problem I've ever seen showed fuel leaking out the carb and into the filter(s), besides into the engine.