Bax,
Looks like I have one of the earlier model FS-70 Ultimates. After trying to fly with it several times (I bought it in 2006) I've decided I'm being bit by the same problems reported here and in other posts.....dies when warm. When cool it runs great for a while, but when it warms up it starts stuttering and dies. I tuned it per all of the instructions and it runs great through all throttle positions when cool.

The question is, will changing the pump assembly help? I thought I read that the pump is the only difference between the old models and the new, and if that's the case I'll spend the money to keep this engine, especially if it will run like it's cool all the time!

Thanks, Steve

A new pump unit should help.

Thanks for the reply Bax. Is it safe to assume that all of the replacement pumps out there, say at Tower Hobbies, are the newer models?

Steve

Bax,
Looks like the new pump is not the solution. I ran the ultimate with the new pump unit today on my test stand and it's the same old thing. Starts easy, runs great for about 3 minutes and then just dies....and it's hotter than hell! I even switched to using 20/20 YS fuel, but after 3 test runs you can almost time to within 10 seconds when she'll die!

I'm throwing in the towel on this engine. Looks like the new FL-70 will fit almost exactly into the same spot, but the throttle and needle are opposite. Can these be changed on the FL-70 or am I going to have to redo my throttle setup (I already have hole in the top of the cowl!).

Steve

I got the same engine with the same head ake won't OS let you in on the secrete to the seccess of the engine. Or make it right some how, exchange or fix would be nice. Email [email protected] if you got a fix...