Saturday, August 18, 2007

.8 hrs: Fuel pressure finally fixed

After a failed attempt to fix the sky-high fuel pressure with a new fuel pump, I tried a bunch more things today and one of them worked. I suspect the problem was that the faston tabs on the (Dynon-supplied) pressure sender are a bit on the thin side, so they don't make good contact. This only became apparent when I tried to pull the fastons off to replace them. Even brand-new fastons didn't grip that well, so I soldered them on.

I also enlarged the restrictor fitting to the sender (on the theory that the fuel was boiling in the line, and couldn't vent the pressure), and filled the sender line up with fuel (larger volume harder to boil)...I guess these could have fixed it too.

3 PSI, I think the only time I've ever seen this in the green! It's always shown 6 or higher, sometimes as much as 20. No more wondering if fuel is spraying out the carburetor throat! (Supposedly the needle valve starts to leak at 14 PSI, but I guess I never really had 14 PSI...)

1 comment:

Anonymous said...

Thanks for the Post. I have the same problem on my RV-8. My Dynon gave me an alarm on final which woke me up considerably. Still, the engine ran fine in spite of the indicated '25 psi'. Ground check indicated no problems, so will focus in on the sender as well.

Again thanks,
RV-8 20 hrs.