sick 91AC
 

Hi Dave,

a friend of mine has a 91AC which has run beautifully over the last few years. However, recently it has started hesitating at mid throttle. It seems to stop firing for 1/4 - 1/2 second every two to three seconds as though it is losing fuel pressure or glow.

We have between us tried pretty much everything in the book - new plug, new diaphragm, new gaskets, new fuel of various nitro levels (we are using Wildcat fuels between 15% and 30% nitro) and have stipped it down several times to look for blockages but it is spotless inside.

The fuel system has been checked out with new lines and the one way valve has been cleaned - it will hold pressure over night so there doesn't appear to be a problem there.

We have also tried adjusting the regulator in and out about 2 turns (!!) either side of flush and nothing seems to make any difference.

We are all out of ideas - do you have any thoughts?

thanks very much.

James

sick 91AC
 

Sounds like the top end is worn out. You might need to send it in for service.

sick 91AC
 

The compression is as good as new - we've both got brand new ones to compare with. Do you mean valves/rockers?

Whatever, like you say I guess the best thing will be to send it in for some professional TLC.

sick 91AC
 

If it has a good seal, there can't be much wrong with it, but I think you'll save a lot of time by letting us take a look at it.

sick 91AC
 

Dave,

it's been sent to Phil Williams of Probuild, the UK YS top man, to take a look over. Thanks for your help.

James