Fuel injection mixture adjustment?

[Xkuzme1]

This is the fuel injection on my F-4.

Can anyone identify it, or tell me how to adjust the mixture?

The engine is running extremely rich. So rich that if the mixture if full rich, the engine stumbles.

Thanks,

X

 

[JonJay]

Are you saying anytime you are full rich it stumbles or just at idle?

 

[Walt]

The star wheel on the RH side, there’s an arrow on the block that shows which way to turn it. 2 or 3 clicks then try it , repeat as nec.

 

[Xkuzme1]

Are you saying anytime you are full rich it stumbles or just at idle?

It stumbles at idle, or under power when full rich.

 

[Xkuzme1]

The star wheel on the RH side, there’s an arrow on the block that shows which way to turn it. 2 or 3 clicks then try it , repeat as nec.

Thanks!

 

[JonJay]

Well, I’m surprised that you get a stumble at any throttle setting. That would be extremely rich.
Download the procedures for your fuel injector. It will go something like ….Engine to be at operating temperature, clear with throttle, adjust mixture, Slowly, and smoothly, cut off mixture and observe rpm rise. Rise should be as per your manual but usually 10-50rpm increase.
You then need to adjust your idle rpm with the idle stop screw as it will change. Repeat the procedure until you have a proper rpm rise during cutoff and proper idle rpm.
If you are indeed this far out of adjustment it’s going to take some fiddling. Make sure you clear with throttle between each adjustment to unload the engine and get a true reading.
That’s the basics.
Good luck.

 

[wcalvert]

Any history leading up to this issue? "been doing it for a while now ..." "Just started out of the blue ..." " happened after I changed the ... "? "getting ready for first flight ..."

Good troubleshooting sometimes involves background. Just askin'

 

[Xkuzme1]

Any history leading up to this issue? "been doing it for a while now ..." "Just started out of the blue ..." " happened after I changed the ... "? "getting ready for first flight ..."

Good troubleshooting sometimes involves background. Just askin'

I have 1.5 hours in the airplane since built. It’s a new engine, so I want to run it as rich as possible, but right now it’s touch because full rich drowns the engine. About 4 tt hours in it. Built by Lyco.

Any history leading up to this issue? "been doing it for a while now ..." "Just started out of the blue ..." " happened after I changed the ... "? "getting ready for first flight ..."

Good troubleshooting sometimes involves background. Just askin'

It’s a brand new engine, and brand new build. 4-ish hours on the Lyco built engine, and 1.5 hours of flight time.

 

[Taltruda]

You shouldn’t want to run it as “Rich as possible”. That excess fuel is just going to wash the oil off the pistons and could do damage. You want to slightly on the rich side, but not “as rich as possible”. Like the previous poster, you should have the idle mixture so that you get a 50 rpm rise just before cuttoff. I would strongly recommend you get someone to look things over (mixture, timing, prop low pitch stops, ect..) before you run it again, and especially before you fly it. Setting the idle mixture is pretty basic, being that you needed to ask shows that you might benefit from an experienced mechanic looking some things over. Don’t read this wrong, I’m glad that you posted the question and asked, that’s great! Lots of people build a plane but really could use a second set of eyes to look at things once that assembly of parts becomes an airplane.