Is it time for Seafoam?

[M61A1MECH]

I stopped for gas today after a short fast run down the interstate, when I was idling waiting for a pump the left pipe starts backfiring. When I got home one of the the left carb boots had raw gas running down it.

What is tke likely cause and repair.

Thanks

[BOO]

I stopped for gas today after a short fast run down the interstate, when I was idling waiting for a pump the left pipe starts backfiring. When I got home one of the the left carb boots had raw gas running down it.

What is tke likely cause and repair.

Thanks

 

Float stuck? Some kind of debris in the float needle/seat.

Sea Foam is a good place to start but you'll probably have to take the Carb apart and clean/unstick whatever is causing the problem.

BOO

[V7Goose]

Got me stumped here - nothing should put raw gas running down the carb boots. If you have a stuck float, the overflow hose should route the gas to up by one of the air filters. I'll have to think about this a bit . . .

Goose

[bkuhr]

Shot in the dark here.

 

State you see raw gas running down boot, I assume this means visable on outside of boot.

 

If this is the case, then maybe leaking fuel line above carb spilling gas down sides of carb, and small airleak below carb, allowing leaking gas to be sucked into manifold.

 

Hey, I started this with 'Shot in the dark here'

[1BigDog]

Steve, your still under warranty..unless its a simple fix, let the dealer look at it first.

[Yammer Dan]

Time for the Stealer to look at it!!

[wes0778]

Turn the gas selector off and run the engine 'til it quits. turn the key off and the gas back on. Now turn the key back on until the fuel pump quits ticking. That may flush out anything under the needle, if that is the problem. Good luck!!!

[RSTDdog]

Has the bike been sitting up for any length of time prior to this?

 

If the the carburetor is dirty or its a fuel contamination issue, this won't be covered under warranty unless your dealer likes you and is creative with the warranty claim.

 

Are you sure its fuel on the the left carb boot and not oil? Mine was oil. Prior owner either overfilled it or it had fuel in the oil from sitting. Causes oil in the airbox and it leaks out usuallly on the left (side stand side)

 

I just cured my pop/backfire on decel by resetting the floats per Gooses tech article. I also cleaned jets while I was in there for grins, but none of them were clogged. I replaced the orings on the brass float seats. Runs much crisper. No pop in 1300 miles of riding from Atlanta to Indy and back and thats with exhaust Y's that both leak.

 

Anyway if its flooding, its float/fuel level related. The excess unburned fuel will ignite in the exhaust causing the backfire (after fire).

 

Seafoam may fix it depending on what it is, but unlikely IMO.

 

If you have the appropriate allen socket, you can try draining the carbs in conjunction with the trick mentioned above. The float valves have very fine mesh screens on them, so the odds of it being a piece of debris is slim. If its been sitting varnish will stick them. This doesn't long with E10 gas.

 

rstddog

[M61A1MECH]

I pulled the tank, the left carb cover and the left top air box, nothing obvious.

It was definatly raw fuel on the outside of the lower carb boot, wiped it with my finger and did the sniff test, plus there was a very stong odor of fuel in the garage for a long time after. The vent line for the overflow is tee'd into both carbs just about middle of the black covers on the carbs, it possible that the float stuck and one of those joints on the tee leaked causing the fuel to flow onto the black cover, which was also damp with fuel.

 

The bike has set for a few weeks, I ran it to work yesterday and today , about 50 miles round trip, it did not happen until I was low on fuel, so I may have picked up a bit of trash, but with the screen on the feed tube in the tank, the filter and the screens in the carbs it does not sound very likely, probably varnish that broke loose.

 

Bike runs fine under throttle, so I am thinking it is sticking float needle valve.

 

I was thinking about running carbs dry to try and flush them, I will probably run some Seafoam through it and see if that helps.

 

The bike is still under warrenty, but am sure this will be judged normal wear and tear issue not covered by the warrenty.

 

It may end up back at the dealer, I do most of my own maitenance, but I learned a long time ago that carburetors don't like it when I work on them.

Thanks for the help, I will update when I know something.

[V7Goose]

I still cannot come up with anything that could possibly cause fuel to run down the carb boot UNLESS the overflow vent hose is disconnected. You can see these easily if you remove the tank and the black plastic air plenums above the carbs. The vent hoses connect to a T between the two carbs on each side.

 

I do assume you know raw fuel when you say that is what you saw. It is absolutely normal on all RSV and RSTDs with a few miles on them to have an oily mess on the left rear carb and the rubber boot above it (I have discussed this in several older threads), but that does not look like raw gas.

 

The only other possibility I can come up with would be the fuel line damaged by rubbing on something. I have never seen that on this engine, but that doesn't mean it can't happen!

Goose

[Guest tx2sturgis]

Is there any possibility that the seal around the fuel level sending unit is leaking? Although that would not cause it to backfire...hmmm....unless....oh never mind...its too late for me to think and Goose will likely figure it out anyway...

 

 

 

 

Edited September 2, 2010 by tx2sturgis

[V7Goose]

I pulled the tank, the left carb cover and the left top air box, nothing obvious.

It was definatly raw fuel on the outside of the lower carb boot, wiped it with my finger and did the sniff test, plus there was a very stong odor of fuel in the garage for a long time after. The vent line for the overflow is tee'd into both carbs just about middle of the black covers on the carbs, it possible that the float stuck and one of those joints on the tee leaked causing the fuel to flow onto the black cover, which was also damp with fuel.

Well, this is a little more information, but I'm not sure it is exactly clear. But it does give me a couple of more ideas.

 

You say the raw fuel was on the outside of the "lower carb boot" - by this I think you mean the tube that connects the carburetor to the engine? I call this the intake manifold, and Yamahaha calls it a "Joint, carburetor".

 

If there is raw fuel below the carb, there is a slight possibility it could be leaking by the rubber gasket that attaches the carb to the manifold. A true backfire (explosion back through the intake valve into the carb) from this engine is very rare, but if something did cause that, it could have upset the fit of the carb to the manifold. That bottom clamp on the carb CANNOT be over-tightened, as there is a metal collar in the middle of the clamp that prevents it from being tightened beyond the contact point. This metal-to-metal contact on those lower clamps is why the screws often stick so bad they round out when you try to remove the carbs. Anyway, the only real check here is to make sure the clamp is in the right position, does not move with your fingers, and the carb is fully seated on the manifold.

 

However, you also said the "black cover" on the carb was also damp with fuel. Did you mean the round black plastic covers for the diaphragm? If so, this says the ONLY place raw fuel could have been coming from is either above the carb or from the diaphragm cover itself. In either case, something significant is wrong. I cannot think of any way fuel would have leaked out of the vent hose connection unless the vent hose was kinked - unlikely, but possible. And even if it was kinked, enough fuel pressure in the carb to force the gas though that hose connection and onto the carb would almost certainly have forced some through the kink and out onto the back of the lower cowling under the air filter. The vent hose from the left carbs gos to the RIGHT air filter unless someone has changed it, so be sure to check both sides.

 

All in all, I'd say this is definitely a warranty problem. Your bike has a 5 year unlimited mile warranty, and anything that causes leaking fuel would definitely be covered. In addition, anything that affects the proper running of the engine would be covered unless it was caused by a part that specifically requires periodic maintenance in the service specs. There is no part in the carburetor that requires any service or replacement, so any problem there has to be covered. Even if something is stuck in the float valve, the argument would be that with the un-modified fuel system, including the screens and in-line fuel filter, it would be impossible for something to be inside the carb unless it was there from the factory. The only exception here would be jets plugged from gum or varnish if the bike sat too long. But plugged jets do not cause leaking fuel.

 

Good luck,

Goose

[M61A1MECH]

Hey Goose thanks for the info, yeah some of my nomeclature is not the same as yours, but you IDed the parts I was talking about, the backfire was not thru the carb, I guess the correct term is after fire, because it was a popping from the left exhaust. Like I said once I got it apart to where I could see what may have been leaking there was nothing obvious. I am going to put it all back together , less the chrome carb covers so I can see a bit better and run the carbs dry and see what happens. if there is anything meaningful to photograph I take some some pics.

[M61A1MECH]

I am not sure what it was all about, I put it back together tonight , idled it till it quit for lack of fuel, put about 1/3 of a can of Seafoam in the tank, turned the petcock on let it run at idle, no pops no leaks. Ran about 10 miles, about half way through shut the petcock off again and let it run till it started to sputter, back on with the gas, no problems. Got back to house no leaks, dry as a bone.

 

I will take it out tommorrow for a good long run and see what happens.

 

If it breaks, I have roadside assistance.

[N3FOL]

 

I do assume you know raw fuel when you say that is what you saw. It is absolutely normal on all RSV and RSTDs with a few miles on them to have an oily mess on the left rear carb and the rubber boot above it (I have discussed this in several older threads), but that does not look like raw gas.

 

Goose

 

This is what I thought is being described on the issue. My bike does have that oily mess mentioned by Goose, but I just get a rag and wipe it clean time to time. Not worried about the 'oily mess' right now for the bike is running fine (knocking on wood).

 

Keep on riding and ride safe. Regards.

[RSTDdog]

When I had my carbs apart, the oring for the brass float valve was not in great shape. There was also oxidation build up ( water attraction from ethanol)on the aluminum sealing surface/wall for the oring where it seats in the carb body. The carburetors were other wise very clean and not varnished from sitting. A poor oring seal on the brass float valve can cause fuel to seep by even if the float holds the needle closed.

 

The only way you will know if sea foam fixed it is to let it sit for a couple weeks. I'm guessing if its a slow seep, it will recur. Mine would flood the left rear if I let it sit a period of time. Riding regularly it was not an issue other than afterfire on decel.

 

rstddog

[WisonKev]

I have an 86 Venture and have a similar/same problem. I have gas running down the left rear carburetor joint (carburetor boot) and I cannot tell where it is coming from. I noticed it about a year ago but it was rather insignificant and I would just keep the area clean. However, it now is to the point that I am concerned about the bike starting on fire. I have several parts removed from the bike as I just did a valve clearance check. I am going to try some of the suggestions on this post and hope for the best. I would like at least like to get through the summer riding season and possibly rebuild the carburetors next winter.

[eagleeye]

If you still have the carbs off, I'd to that rebuild now. It doesn't take all that long. Read the last post about the oxidation buildup from using ethenal. I took mine apart to clean that mess up. (white buildup from ethenal)