Carb blowing fuel out air horn!!!!

[734406pk]

Seems to be heat related - ran good yesterday in low 20's (Celsius). Today started spewing close to home in the 28 Celsius range - fuel pump was also very loud (Holley billet electric). Between this, the oil leak the engine shop can't seem to fix, and my street bike with intermittent start issues - almost time to sell all the toys and buy a good pair of shoes and go for a walk.

Possible fuel boiling condition? Since you mention the Holley EFP getting very loud at the same time could indicate that it is pumping boiling/aerated fuel from the suction side of the pump. A restriction in the supply line to the pump will cause a lower fuel boiling point. Check over your fuel lines for kinks etc. Or you can tee in a vacuum gauge on the suction side of the the Holley EFP , disconnect the carb. feed line and route it into a container. Turn on the fuel pump and read the restriction on the vacuum gauge during full fuel flow. It should be very low (< 3.0 InHg). The greater the restriction, the lower the boiling point. Shield all of the fuel lines from exhaust heat as best as possible can help.

[BS CUDA]

Spoke with Holley tech today and explained my set up and routing of lines etc. They are almost certain it is heat soak at the carb bowls and suggest a carb heat shield.  No harm in trying it and they look cheap enough - just need to find one locally. Suppose I   could build one if it came down to it.

[734406pk]

Here is one supplier:
http://www.coolcarb.com/

[73440]

I have used the heat shield from DEI.

http://www.designengineering.com/catalog/design-engineering-inc/line-hose-protection

Probably combination of insulating the line, maybe a spacer and the cool carb.

[BS CUDA]

Ended up with this one from Holley - it was the only one available on the shelf. Hopefully this does the trick - I may still end up trying to insulate the fuel line itself as well. Certainly can't hurt!

https://www.holley.com/products/fuel_systems/carburetor_components/adapters_and_spacers/parts/108-70

[734406pk]

Good Luck! Hope it works!

[BS CUDA]

So far so good - hasn't been 30 C since but flogging her hard @ 24 and 26 degree C and symptoms seem to be gone. I am still going to insulate the lines in the engine bay with DEI heat shield wrap that will cool things further.
Current temps within a few degrees:
Intake 155F
Carb bowl 115F
Fuel feed line that runs next to intake 145 - 150F
Fuel line running along fender to regulator 130 - 140F (about 6" from header all along)
Fuel still seems to likely be entering carb hot but not enough to boil - or so it seems. Fingers crossed!!!!

Oh and the engine shop solved the rear main leak - 4 attempts - something bout ARP studs / nuts not allowing the retainer to fully seat.   

[73440]

If you don't want to remove the lines, this DEI one velcros on.
https://www.designengineering.com//category/catalog/design-engineering-inc/line-hose-protection/heat-shroud

If you remove the line, https://www.designengineering.com//category/catalog/dei-cycle/line-sleeving/heat-sheath-aluminized-sleeving

[734406pk]

I would say the fuel supply line needs some insulating big time! That's hot!

[BS CUDA]

DEI has some really nice product!!!

Yes the supply line is hotter than I would have suspected. It's running much better now but still has a bunch of room for improvement.

[734406pk]

DEI has some really nice product!!!

Yes the supply line is hotter than I would have suspected. It's running much better now but still has a bunch of room for improvement.

 

[Chryco Psycho]

Glad you got the oil leak solved