Fuel Pressure Low until Engine Warmed
I believe we have a failing Mechanical Engine Driven Fuel Pump here, two mechanics agree independently, but wanted to throw this out to see if anyone has seen this before.
Lyc 0320, Ellison
Normal Operating Range 3-5 psi
New Fuel Pump, approx. 40 hours since new. Purchased 15 months ago or so.
Fuel Pressure on startup, less than 1 psi. Engine will run fine at all throttle settings except near full or at full throttle. The Ellison system will not throttle back, it will simply cut out if inadequate fuel pressure for throttle setting isn't present, which is what it is doing.
Fuel Pressure does not increase with an increase in engine rpm.
The Wobble Pump easily brings pressure into the green at any state including engine not running.
Fuel Pressure rises into green once engine is at or near operating temps. At operating temperatures, Fuel Pressure stays in the green, and rock steady through all power settings with normal slight variances.
I reviewed the cool video from Tempest "the amazing ubiquitous fuel pump". The only thing I can imagine is one, or both, of the valves are staying open until the engine heat free's it up, allowing the pump to operate normally.
This is not in an RV. The fuel system is a header/main tank mounted much higher than the fuel pump. I am assuming that there is enough pressure from gravity for the engine to operate without the fuel pump except at higher throttle settings.
If anyone has seen this before, please chime in. We have a replacement pump coming but I thought I would post for education purposes, mine and others.
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