jasonlacey

[] Ihave just installed a Saito FA 72 in a cub. The engine was bench run for three big tankfulls.the trouble im having with the installation is, when i turn the prop counter clock to prime it sucks fuel from the carb to the tank! I have checked the lines etc What the heck am I missing(other than my smarts today!) All,well most, suggestions welcome Thanks

Rcpilot

My Feedback: (78)

Maybe, adjust the valves? Can't see why valve adjustment would effect fuel draw, but it's easy to do and won't hurt anything.

asmund

thats a new one! try to reverse your fuel lines, just kidding if the line connected to the clunk in the tank is connected to the needle at the carb, and the engine ran well during bench running I can`t see how this is happening [:@] if the lines is switched, the carb would only suck air from the muffler. I`m lost here too

Cyclic Hardover

My Feedback: (3)

Is your fuel tank upside down, thus reversing the lines.

asmund

but then the clunk would still be at the bottom sucking in the fuel like when in inverted flying right? and the other line would still let air in to the tank to compensate for the fuel beeing drawn out,

jasonlacey

The engine ran well on the bench with a diffferent set up.It is only when I put it in the cub that the problem appeared.My first action was to only partially fill the tank to check the fuel line connections,they where OK.I blew into the pressure line and turned over the prop this pushed fuel into the carb,but when I blocked the exhaust and did normal prime procedure thats when it sucked it right back out !!(The fuel that is)

redfox435cat

I'd try pulling tank disassemble it and reassemble it and try priming it with this tank attached outside the model to see what's going on. still sound like a tank and pluming issue. These engine pull fuel with authority when there plumbed right

Once I hooked up the crank vent to the tank and the muffler fitting to bottom of the fuse and didn't realize it. We all have our days right[:'(]

Kweasel

My Feedback: (29)

Flip the prop faster when priming. On newer engines the intake valve closes well after the piston is at the bottom of the stroke. If the prop is turned slowly the intake will blow back just before the valve closes.

William Robison

My Feedback: (3)

Jason:

Of all the suggestions Kweasel's makes the most sense to me, but the exhaust valve has timing every bit as "Radical" is the intake.

My thought is that you are trying to prime and start the engine with the throttle too far shut. Crank it open to about 1/4 and try it. I think your problem will go away.

Bill.

William Robison

My Feedback: (3)

Further note on throttle at start - I've never been able to start a Saito easily unless the throttle was at least 1/4 open on the first sstart of the day. Restarts are usually OK at idle.

Bill.