A

ARJAY

Member
The 9A I traded for has a 320/160 Hp carbureted engine and the fuel pressure gauge always reads below 5 PSI.
What is the safe range for this system.
 
What type of gauge do you have. My Van's fuel pressure gauge also reads low fuel pressure. Usually around 3-5 lbs.

It's been like that for 240 hrs and, like you, was concerned initially but determined from reading on VAF forums that the readings are normal for a carb engine. My engine has never missed a beat even when the gauge read low (3 lbs or less).

I did a fuel flow test with the tail of my -6 in a ditch simulating a high angle take off. Fuel flow was over 24 gph (IIRC) with the aux pump on and the gauge still read below 5 lbs.

It doesn't bother me any longer and when my wife/co-pilot point to it, I flip on the aux fuel pump for a few minutes to relieve her concern.

nwepz6.jpg


or3pyo.jpg
 
Last edited:
mine is low also

seems like my pressure gauge is more of a temperature gauge then a pressure gauge as it changes more based on what i am doing , startup, climbout cruise etc.after the mechanical pump i have aprox. 16 inches of hose to the transducer.
 
2 to 4

Mine is always below 5 according to Vans steam gage. Could drop down to 2 on a colder day. Normal operation recorded at 1 psi for 30 minutes as well. Aux pump will boost it up within seconds.
 
why is this?

Vlad said:
Mine is always below 5 according to Vans steam gage. Could drop down to 2 on a colder day. Normal operation recorded at 1 psi for 30 minutes as well. Aux pump will boost it up within seconds.
Click to expand...

I've noticed fuel pressure variation with temperature but can't correlate it. It seems fuel pressure should be higher when it is colder. Is it the instrumentation or real? When boost pump is on, always 5-8 psi.
 
Safety tip

There was a fuel fire in a hangar near here last year when some folks were draining a fuel tank into a bucket. Please consider putting a metal rod (hinge pin material works fine) into the container and grounding it to the plane. One small pop of even static electricity and that beautiful plane you spent so long and so many $s on could go up in flames. Your personal safety is to be considered as well. In the fire, the freshly completed plane was lost. Fortunately the fire was extinguished before any of the several other aircraft in the hangar were destroyed. Be careful with fuel.
 
good advice Mark!

Skysailor said:
There was a fuel fire in a hangar near here last year when some folks were draining a fuel tank into a bucket. Please consider putting a metal rod (hinge pin material works fine) into the container and grounding it to the plane. One small pop of even static electricity and that beautiful plane you spent so long and so many $s on could go up in flames. Your personal safety is to be considered as well. In the fire, the freshly completed plane was lost. Fortunately the fire was extinguished before any of the several other aircraft in the hangar were destroyed. Be careful with fuel.
Click to expand...

FWIW, my fuel pressure is also 1 - 3 psi during normal ops. Nary a stumble, aux pump on for all critical phases of flight of course.

I read a good article on bonding fuel components during fueling, especially from plastic jugs, funnels etc. Doing anything fuel or solvent related IN a hangar of course multiplies the risk.
Now I know why there always seems to be a guy standing by with a BIG fire extinguisher, anytime someone is doing any engine related work in the air force or commercial ramps.
 
Steve Melton said:
I've noticed fuel pressure variation with temperature but can't correlate it. It seems fuel pressure should be higher when it is colder. Is it the instrumentation or real? When boost pump is on, always 5-8 psi.
Click to expand...

Could be instrumentation Steve. Couple days ago it was really cold and fuel pressure on Vans gage was reading 7. Even without the aux pump.
 
Mine goes to zero when I turn of pump while climbing out. As soon as I lean it just a little, I get around 2psi. Don't know if this is normal.
 
full tanks, 6 psi at -11C

6 psi with full tanks at -11C without boost pump, measured with IK technologies engine monitor. not sure if it's instrument error because of the cold temp or real. with warmer temperatures the reading is 2-4 psi.
 
Low pressure reading solved

My RV4 had an intermittent low pressure indication at various stages of flight. The engine never stumbled but sometimes the pressure would approach the low peg. Turning on the electric pump brought pressure back to 5. The last thing I did to the fuel system was to replace the Facet pump and the low pressure symptoms went away. I surmise that the electric pump has a bypass that allows the mechanical pump to draw through it. I believe that the low pressure was caused by a partial restriction in the bypass.
 
You must log in or register to reply here.