Howdy folks, I have an older blue case Brison 3.2 that has run flawlessly for the past 2 years. Today I went to the field and flew 2 uneventful flights. I took a break for about 30 minutes and topped off the batteries for general principals. When I went to fire it up for my third flight it started right up but it would just quit if I advanced the throttle past high idle (about 2000 rpms). Tried it a few more times and the same thing. I pulled the cowl and checked the fuel filter and the little carb screen and they were clean. I put a new spark plug in it and checked all the fuel tank plumbing and everything was good and tight and secured. Ignition battery was fully charged and was putting out 5.2 under load. The engine will idle indefinatly but dies when the throttle is advanced. What do you guys think is happening? Also, this is about the 10th run after switching to the new 10% methanol blend gas. Are my seals and diaphrams being affected by the alky?[]

Is this a mechanical advance or electronic advance?

Hi Bass,
I'd make sure that the carb is nice and tight, no vacuum leaks etc. Turn in the needles to get the settings and pull them out and check for crud inside. The diaphrams my just be old and need replacement.

Dave

It's a mechanical advance. I just removed the needles and there was a tiny speck of something on the low needle tip, very tiny. The carb is tight and there are no obvious leaks.

It sure does seem like it is suffering from fuel starvation. I take it you have an inline fuel filter. I know that you checked it but you might put a piece of brass tubing in it's place for a test. Did you actually pull the carb screen out and hold it up to the light. I have found that sometimes a clear film can form on the screen making it look clean.

See if you can find a friend with a spare carb or one that could be pulled off of his engine just to see if the rpm would come back up.

I've been running the 10% ethanol blend for about 2 months with no problems, however, this might be your problem. The jury is still out.

I just pulled the screen out and held it up to the light and there was a tiny bit of stuff on it, maybe 5% of it was covered. The little speck of stuff on the low needle tip was clear but doesn't seem like it would have caused that much of a problem

I bet it is now back to running great... I had the same problem with mine four years ago and it was a tiny speck of stuff in the low end needle. That small speck was enough to cause a slightly lean low end not allowing transition off of idle.

Well, live and learn. Thanks Dave for the suggestion of checking for crud on the needles and you were right Wings, that tiny little transparent speck on the low needle was my problem also. She's BACK!!