7KCAB Fuel injected engine Skip at idle

F

fla115

New member
Guys my engine with 20 SMOH has a slight skip at idle during taxi. It is not there at any other RPM range and the engine is very smooth at cruise and full power. Leaning the mixture has no effevt on the skip. It is almost like a "lope" in the engine at low RPM.

Any help would be appreciated,

Thanks
Steve
 
Steve...... I have a 67 7KCAB and it does the same thing during taxi when it is warm. I have had the plane for seven years and have checked everything in the fuel and ignition systems. It runs great under power. Does it happen if you taxi with the boost pump on?

Jim
 
Jim, thanks for the reply. It appears to run really rich with the boost pump on at idle and does not like it at all. It is worse when the egine is hot and sounds like it is lean at idle but I am getting the prescribed 50 rpm rise when shutting down the engine with mixture cut off. I have checked for induction leaks and have found none. Have not messed with the idle mixture yet since I am getting the 50 rpm increas at shutoff. The engine runs great at mid range and very nicely at cruise. I have a lot of experience with Carb engines but none with fuel injection.

Thanks again for the reply.

Steve
 
Jerry, I had not thought of vapor lock. I am running 100 LL and the problem is only at idle. The engine skips a little when warm and pops when taxing back in after a flight when the engine is hot.

It has all the symptons of being overly lean at idle.

What would be best way to check if vapor lock could be an issue?

Thanks for your response.
Steve
 
I tihnk we set our 8KCAB around 600-700.
Might just try tweeking it up a notch or two and see if the wee little bit of extra flow helps. You can always turn it down again.
 
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