Fuel Pressure

[merrja]

HI All,

I just had a complete overhaul and new fuel pump installed as well and have about 28 hours on the engine so far.

The issues (or maybe not an issue) is that the fuel pressure runs about 30 psi ( I was told this will come down once the fuel pump wears in), but it will run constantly about 29-30 psi, then after a few minutes drop to about 25 psi for only a few seconds.  I've confirmed the readings on both my EI fuel pressure gauge as well as the original fuel pressure steam gauge. 

Any ideas?

 

Thanks!

Jim

[N201MKTurbo]

I assume this pressure is on the mechanical pump with the boost pump off. It is controlled by the spring in the fuel pump. I wouldn't worry about it. As far as the negative spikes, those are almost always caused by air leaking into your fuel system. 

[MARZ]

Curious as to what the electric boost pressure is supposed to be as well

[carusoam]

There are a few recent posts regarding the new mechanical pump high fuel P situation.

Finding them may be helpful To see the number that are going on in a similar time frame....

Best regards,

-a-

[RobertGary1]

Are you referring to the mechanical pump? I've got about 30 hours TT on my new Lycoming and my pressure holds 29 in all phases on the dot like clockwork. I think the previous mechanical pump was middle of the green. The Lycomjng break in yellow sheet shows that is what it ran at the factory too.

My Electric pump runs the same but of course I can no longer tell in flight. Before I replaced it it was near the bottom of the green when priming.

It does sound like you might have an air leak somewhere. This is just at high flow?

 

-Robert

[merrja]

4 hours ago, RobertGary1 said:

Are you referring to the mechanical pump? I've got about 30 hours TT on my new Lycoming and my pressure holds 29 in all phases on the dot like clockwork. I think the previous mechanical pump was middle of the green. The Lycomjng break in yellow sheet shows that is what it ran at the factory too.

My Electric pump runs the same but of course I can no longer tell in flight. Before I replaced it it was near the bottom of the green when priming.

It does sound like you might have an air leak somewhere. This is just at high flow?

 

-Robert

Thanks Robert, The boost pump alone is mid 20s as it was before and I'll need to check on it at lower flow rates, I noticed it in flight coming back on a 3 hour flight. 

[merrja]

On 3/25/2016 at 2:44 PM, N201MKTurbo said:

I assume this pressure is on the mechanical pump with the boost pump off. It is controlled by the spring in the fuel pump. I wouldn't worry about it. As far as the negative spikes, those are almost always caused by air leaking into your fuel system. 

Yes, just the mechanical pump.  Thanks very much.