B-2B Can't get it to Prime

[bryancobb]

Hey Guys:

I just went through a saga and and I thought someone else might benefit from my lessons learned!

Mine is fuel injected. Well during an attempted startup, I could not get a positive fuel-flow indication during priming.

I traced the problem to somewhere between the electric fuel pump and the flow divider, because they both checked out OK.

I freaked when I found that a new engine driven pump was $3000!
I thought that was my problem. (41 oz/min @15 PSI in front of it and 12 oz/min @2 PSI behind it.) It's a vane-type pump and I had nightmares of a vane being broken off -- obstructing fuel flow -- and was feeling thankful to be alive since I had just flown the day before and thought "what if that obstruction had happened in flight?"

Well ... Harold Jenkins told me to check the 1-way check valve behind the passenger seat. YES it was stuck open and upon disassembling it to check it I found the piston inside was binding in its' cylinder. This caused pumped fuel from the electric pump to flow right back into the tank AFTER leaving the engine driven pump, instead of building up enough pressure to unseat the needle in the flow divider and squirt fuel into the cylinders to prime it.

A new $70.00 check-valve fixed it! (Cleaning it didn't help)

Hope this helps,
Bryan

[Ron Spiker]

Great tip Bryan. That's one to keep in the books for when I need it.

Thanks

[bryancobb]

Hey guys:

After I got my New check-valve on.... my fuel pressure is too high with and without the AUX Pump on. (24 to 27 PSI)
I guess the check-valve has been leaking for years and each mechanic kept tweaking up the pressure on both pumps to keep it in the green.

Now I have to dial them both back down!

Boy! That high fuel pressure made hot starting a breeze! I may call the factory or Lycoming and see if I can leave it that way!

Bryan