I’d be interested to know what kind of fuel pressure people are seeing when using the low pressure engine driven pump on a Lycoming O-360.
The cockpit gauge in my aircraft, which is new to me (Permit Jodel D.140), indicates from 0-15 psi; in flight I get almost nothing from the engine driven pump, and a maximum of 4 when using the electric pump.
Lycoming specs are 0.5 min / 5 desired / 8 max. We have tested the pumps on the ground, plumbing in an extra gauge, and achieved 4 on the electric pump and zero on the engine driven pump – this is running up to 1800 rpm. Turning over the engine on the starter with the fuel pipe disconnected at the carb produces a modest fuel flow – but beyond that I have no idea of how to quantify it.
I am prob 90 going to replace the mechanical fuel pump because as it currently stands:
a) according to my understanding, it isn’t working as it should, despite possibly being within Lycoming specs.
b) I would have no idea of knowing if the mechanical pump had failed and may thus being be relying exclusively on the electrical pump.
What is holding me back is that:
a) This is a problem I have gone looking for – the engine runs faultlessly on the engine driven pump.
b) 0.5 psi is within specs but probabally not discernible on my gauge.
c) All thus messing around with the fuel system might make a MIF more likely than there being a real failure of the engine driven fuel pump.
What do the panel think?
We have a PA28-181 with an Lyc. O-360. The engine-driven pump gives fuel pressure at or slightly above the 5 psi line on the fuel pressure gauge. Same with the electric pump.
I get about 4 psi on a carbureted O-320, with either mechanical or electric pump, arranged in a similar configuration to that of a Warrior. I’d replace your mechanical pump and suspect all will be fine when you do. Also make sure any check valves are working, so that either pump can make pressure.
A carbureted engine only needs enough pressure to overcome the (minimal) fuel line loss at the required flow, so tends to be fault tolerant in that regard.
Thanks AA; would you expect that from the EDP @1800 on the ground?
NickL wrote:
Thanks AA; would you expect that from the EDP @1800 on the ground?
I would expect that when idling on the ground! Certainly at 1800 rpm.
Thanks Guys,
I’m replacing the mechanical pump on Wednesday – will report back.
Nick thats a nice aircraft you,ve purchased I put a bid in for that one.My Robin 400 has the same engine as your Jodel.Fuel pressure is graduated in mbar on the gauge and I normally have full scale defelection of 350 mbar with either electric or mechanical or both pumps operating.The red line is set at 80 mbar which I believe is 1.1 psi.Hope this is helpful.Regards Stampe.
Thanks Stampe (Assuming it’s ST you are thinking of).
I’m loving the aircraft – It is my first experience of the Robin / Jodel and I’m impressed. Handles beautifully, great viz, will lift a good load out of a strip, just not particularly quick.
The new pump has been installed and I’m now getting 4 psi on both pumps. I haven’t had the bill yet…
Nick thats the one I,m a real fan of the big Jodel superstol and spacious and was planning to run it as a second aeroplane for a couple of years.The daddy of the Robin I was surprised ST only offered 20kgs more payload than the 400/180 with a lower cruise and similar range.What cruise are you getting? Interesting how the Jodel/Robin range evolved and the compromises.You have a lovely example.Regards Stampe
The 400 sounds like quite a machine as well.
It’s early days in terms of gathering data but last time out @ 1500ft 2200rpm / 100 KIAS, 2300 / 104, 2400 / 108, 2500 / 115.
Two up, with half tanks, she gets up and away pretty quickly…
