Tom @ N269CP
Well Known Member
My RV-8 is powered by an O-360-A1A with Marvel Schebler carburetor. The fuel pressure gauge is hard piped to the pressure tap on the inlet of the carb. I've been flying it regularly for the past couple of months.
Fuel pressure normally varies between about 3-6 psig during flight on the mechanical pump alone.
When I fired it up yesterday morning to go flying the fuel pressure was reading about 9 psi on the mechanical pump alone at about 1000 rpm. It read about 5-6 psi before starting on the electric booster pump alone. As fouling/stiction is a concern, my A&P checked the inlet strainer to the carb which was clean. We drained the carb bowl and flowed fuel through it to flush any debris.
After reassembly, I fired it up again this morning and the fuel pressure was still indicating 8+ psi at 1000 rpm with the mechanical pump alone. The pressure held steady at 8 psi after shutdown and even after cycling the mixture lever. We bled the panel gauge and the pressure immediately dropped to less than 1 psi. So the 8-9 psi pressure appears to be real.
I'd be grateful for any ideas and suggestions as to what the cause of this anomaly may be.
Thank you.
Tom
Fuel pressure normally varies between about 3-6 psig during flight on the mechanical pump alone.
When I fired it up yesterday morning to go flying the fuel pressure was reading about 9 psi on the mechanical pump alone at about 1000 rpm. It read about 5-6 psi before starting on the electric booster pump alone. As fouling/stiction is a concern, my A&P checked the inlet strainer to the carb which was clean. We drained the carb bowl and flowed fuel through it to flush any debris.
After reassembly, I fired it up again this morning and the fuel pressure was still indicating 8+ psi at 1000 rpm with the mechanical pump alone. The pressure held steady at 8 psi after shutdown and even after cycling the mixture lever. We bled the panel gauge and the pressure immediately dropped to less than 1 psi. So the 8-9 psi pressure appears to be real.
I'd be grateful for any ideas and suggestions as to what the cause of this anomaly may be.
Thank you.
Tom