Fuel Leak...

[jmpacella17]

So, there was clearly fuel leaking from the bike as it was just sitting. I took the carbs off to see if the floats are not working properly. 2 things: 1) there was a lot fuel just sitting in the head (see pics), and 2) there was a steady flow of fuel from the line (from tank) after removing them from the carbs.

1) Clearly this shouldn’t be happening right? Is it related to the fuel pressure from the pump, or are the floats/valves not working on the left side?

2) Why would there be fuel flowing fairly steadily (normally just a few drips from fuel in the lines then stop)? The tank is not full (the level is well below the carb level). Not a big issue but it still baffled me and made me wonder if it contributed to the overall mystery…

 

[Uncle Phil]

It's almost like your fuel pump is 'running' all the time ...
Just for grins, I'd remove the wires from the top of the tank and see if it still happens.

 

[Al st1100]

So, there was clearly fuel leaking from the bike as it was just sitting. I took the carbs off to see if the floats are not working properly. 2 things: 1) there was a lot fuel just sitting in the head (see pics), and 2) there was a steady flow of fuel from the line (from tank) after removing them from the carbs.

1) Clearly this shouldn’t be happening right? Is it related to the fuel pressure from the pump, or are the floats/valves not working on the left side?

2) Why would there be fuel flowing fairly steadily (normally just a few drips from fuel in the lines then stop)? The tank is not full (the level is well below the carb level). Not a big issue but it still baffled me and made me wonder if it contributed to the overall mystery…

Normal, the fuel tank is under pressure, loosen the fuel cap before taking lines off. If a fuel cut bypass was done that could explain it and or the fuel cut valve could be leaking. In pic 2 the hoses/lines in the center of the pic are over flow lines for carb if the float should stick. Were they connected?

 

[jmpacella17]

I cleaned the carbs, installed a fuel pressure regulator, and put it back together. It ran fantastic…for a short time.
There was a short, mechanical, screeching sound, and then oil was pouring out from somewhere.

I started to tear it down to find the source of the oil leak, and I saw this (part of the cylinder head gasket was dislodged; see photo).

Any idea why this happened? It continued to run fine for the short trip home from the test drive. Can I just put some sealant on this, shove it back in and hope for the best??

 

[ST1100Y]

(part of the cylinder head gasket was dislodged; see photo).

Looks like case over-pressure -> case vent blocked/attached wrong...

I would a) fix that case vent issue, b) get new gaskets + grommets to replace the strained ones...

 

[jmpacella17]

Thank you! I will give it that a whirl…

 

[Ron]

A question on the fuel pump. Do you know if the Quantum's hose was used? It has been known to fail after a while. It should be replaced with submersible hose. Take a big stack of money when you go to buy it. Probably covered in Uncle Phil's post mentioned earlier.

Enough gas will siphon through the pump to run the motor.

 

[jmpacella17]

I think I have it figured out now, all…so the gasket blow out happened, I believe, because the fuel that was being dumped into the heads leaked through the rings and into the crankcase, leading to extra volume, extra pressure. I figured this out when I changed the oil, and it reeked of fuel. Should have thought of that; could have been much worse, I suppose!

But I have the fuel pressure regulator on there now, the carbs have been cleaned, gasket repaired, and she’s running well!

Thank you all for your help! I really appreciate you all on this forum lending your wisdom and expertise…