Nasty misfire

[ultraslow]

Encountered, a nasty misfire yesterday, Checked the usual suspects. Found a fuel leak on rear carbs. Replaced stop nuts. Checked and recheck, no leak on short hops; Started home, it resurfaced. Rechecked dissy position again, wires. fuel leak,has new coil. Problem disappeared after cool down only to resurface a short time later, engine cuts out. It is v-quiet w/o the engine noise. Heat related? Going replace both carb to intake gaskets. W/leak is fuel pressure/regulator too low. Any thoughts?

Ultraslow

[anthonyseven]

Encountered, a nasty misfire yesterday, Checked the usual suspects. Found a fuel leak on rear carbs. Replaced stop nuts. Checked and recheck, no leak on short hops; Started home, it resurfaced. Rechecked dissy position again, wires. fuel leak,has new coil. Problem disappeared after cool down only to resurface a short time later, engine cuts out. It is v-quiet w/o the engine noise. Heat related? Going replace both carb to intake gaskets. W/leak is fuel pressure/regulator too low. Any thoughts?

Ultraslow

 

I had a similar issue once on my Birkin.

 

A hairline crack had formed through the body of one of my Weber DCOE 45 carbs. The mechanic who found it said he had seen this type of failure several times before. It was always on twin carb setups. He said the cracked carb was always in the same position, but I can't remember if it was the front or the rear carb. (Too many years ago.)

 

He was able to repair the cracked body, so I did not need to replace it. Again, I don't remember how he fixed it. http://www.beltfedshooters.com/forum/images/smilies/oldman.gif

[TheDingo8MyBaby]

This thread has a lot of suggestions to try:

 

http://usa7s.com/vb/showthread.php?t=9135

[ultraslow]

Fuel leak was on rear dual. Seemed to be the gasket. Perhaps not. The engine slowly cutting out is confusing, also the waiting and then restarting.?? Crack or gasket leak and marginally low fuel pump pressure. I will pull the rear carb and look. Also will look at linkage for misalignments or breakage. Will let you know. Thanks for the support.

ultraslow

[TheDingo8MyBaby]

How long are you waiting before restarting? I'm now working off the assumption it's heat related. Even though you've recently replaced the coil, an easy way to check it is to stick an ice pack on it and see if your problem goes away.

 

Another thought is boiling fuel (not vapor lock). I assume this is not happening in the bowls, so check your fuel lines for possible heat transfer.

[ultraslow]

Dingo, Just a few minutes which leads me to believe that the "heat" issue may be a misdirection. This may be fuel related. Perhaps the leak is as mentioned above is a crack and not the gasket, I will change anyway when I pull them. So again, misfire develops, engine slowly dies. I wait, checking everything in sight, and bingo it starts. Short trips are fine. Over five min or so and it reappears. Also, coincidentally? starter has quit, solenoid has been sticking. Unrelated?

Ultraslow