Leaking gas when running

Bnolte

New member
#1
Hi all -

Just a received a used 07 bonneville via shipment, and it’s leaking (a lot) of gas after idling for a few minutes, but doesn’t leak when off. Can’t find any obvious hoses or connections out place - and seems like the leak is tucked away (brief video attached)

In addition, the bike was just shipped from FL to CT, and was inspected by a dealership with a clean record. Any thoughts would be greatly appreciated!
 

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rbirkey

NBRAdmin
Staff member
#2
Hello Bnolte, and welcome to NBR! I'm sorry you are getting off to a disappointing start!

I believe the 2007 Bonneville is a carbureted model, like my 2008 Bonneville. If the Bonnie was last used in an area where ethanol was added to the gas, my guess is that one or more of the rubber seals used throughout the carbs are old, cracked and failing. If it was not being ridden and maintained regularly, the Keihin CVK 36 carbs could also be gummed up causing the floats (13) to stick open... allowing fuel to build up in the bottom float bowls and then bypass the float valves (11). Based on the sheer age of the bike, another common possibility is that the U-ring (26) seals at the ends of the connecting tube (25) that runs between the two twin Keihin CVK 36 carbs are worn out and cracked.

Also, it could be as simple as a bad fuel line. Have you checked the connections at the petcock and at the end where it attached to the fuel delivery connector? Perhaps just replacing/repairing that hose and the clamps are all that is needed?

In any case, I recommend removing the carbs and doing a thorough ultrasonic cleaning and rebuild, replacing all the seals, jets, etc. I have been able to call Sudco International in the past (sudco.com) and discuss the parts/kits that I need for my year and model, and order parts. Of course, you can also order parts through your local Triumph dealer. Let us know how it goes! These are great bikes and if we lived closer, I'd be happy to help you out!
 

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Bnolte

New member
#3
Wow - Really appreciate the detailed response rbirkey!

So I was able to resolve the above leak, but now I have a new one it seems. The first leak was due to a loose fitting fuel line. I've replaced the clamp and looks to be ok (I think) and the petcock looks ok / dry.

After filling up the tank, the bike now spits out a decent amount of fuel out of the lower air snorkel (I think that's the right name, pic attached) each time a try and turn it over, and the bike won't start at all. I'm just wondering how fuel could get in there, and could I still have an issue with the fuel delivery connector?

Again, really appreciate all the insights here. It seems clear something happened in transit, uncovering this leak is a puzzle!
 

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rbirkey

NBRAdmin
Staff member
#4
Bnolte,

Yeah, that is a big problem. It seems that somehow gas is getting into your airbox and air cleaner which will definitely hinder starting. You'll need to remove that intake snorkel (I think it requires 3 or 4 8mm hex head screws), then remove the air cleaner. Inspect the inside of the airbox to see if there is gas collecting in the bottom, especially when you turn on the gas flow petcock. That problem will need to be addressed.

Again, it may be that the float valves are sticking open and gas is overflowing, or there may be yet another leak higher up somewhere that allows gas to seep down into the airbox.

I wish I could be there to inspect with you as I have never run across this issue before!

Good luck!

Randy
 

Bnolte

New member
#5
Thanks again Randy - I promise to repay these debts to the thread over time!

I let her sit for a day, decided to try again, and it started up with no leaking...Ran for about 10 minutes, idled out, and now won't start back up. Turns over, but doesn't sound like its getting enough fuel..

So clearly I still have a fuel / fuel line issue, I'll keep trying to diagnose..
 

rbirkey

NBRAdmin
Staff member
#6
So, maybe there was gas in the airbox from the previous leak, and it evaporated over the time you let it sit. That would explain why it started and ran for a while. Hopefully, you do not have a leak that empties into the airbox anymore. Now, as you said, it appears you have a different problem to track down. Do you have any information about the status of the bike before you purchased it? Was it being ridden regularly, or was it sitting for a long time? If it was sitting, was the gas tank empty, and/or was the gas stabilized? That info will help you know where the problem may be.
 

Bnolte

New member
#7
Hey Randy & Crew!

I trust all is well...I continue to diagnose issues. Leaks for the most part have stopped, but bike still has a variable idling range and does stall out, even when shifting gears from 1 to 2nd. So far, I've only been able to ride for about a mile until it stalls out and won't start again, having me to depressingly push my bike home. Suspecting its still a fuel related issue, I wanted to check out the fuel-line filter, and noticed the below discoloration. Coincidentally, the inside of the tank is the same color thats discoloring the filter. Is that normal / natural for a 11 year old bike? I'm planning to replace the part, I would assume that would cause restriction of fuel, thoughts?

Many thanks as always!
 

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rbirkey

NBRAdmin
Staff member
#8
Sorry, that discoloration is not a good sign. The inside of your tank should be shiny bright steel, not brown. It looks like the bike may have sat with low gas during hot/cold cycles and water was able to condense on the inside of the tank and start oxidizing. I think to truly eliminate this, you may need to remove the tank, empty it and refurbish the inside to remove all potential future sources of contaminants. There are chemicals and processes for doing this.
 

Bnolte

New member
#9
Thanks Randy - I'll start with a new filter and trying sea foam in the tank to see if that improves performance. If that doesn't do it I'll go down the tank treatment process.

Thanks again as always..
 
#11
I had the exact same problem where I had gas flooding my airbox. It turned out one of the vacuum lines on my carbs was plugged up. pull each one...one by one and pass some compressed air to make sure its clear...and also make sure the vacuum lines are mounted properly.
 

rbirkey

NBRAdmin
Staff member
#12
I agree. Best practice on a carbed bike that does not run well, and has been sitting or is of unknown background/care is to check, clean and rebuild/replace every intake system part as needed! Especially any rubber/plastic parts that come into contact with the fuel - even more so if the bike used fuel with ethanol added.
 
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