Fuel Pressure Plumbing

[EJS]

For those that are still flying with a factory fuel pressure gauge I am looking for information on how the fuel line from the gauge attaches to the injector servo on a M20E. We currently have a STC that measures nozzle pressure from the flow divider (on top of engine) that distributes fuel to the injectors at each cylinder. That pressure is converted to gals/hr on the gauge. We are converting back to reading unmetered pressure from the mechanical pump. There are two ports on the injector servo that can measure unmetered inlet pressure. I would like to know how the aircraft was set up originally and the manuals are not very clear. Can someone post a picture of the injector servo showing where the fuel pressure line attaches?

Thanks

Eli

[Guest]

Eli,

There is a port on the servo finger screen body between the servo and the oil sump.  It uses a special Mooney elbow which goes I place of the plug.  It is -4 on the servo and -3 for the fuel pressure hose.

In a standard installation there were no pressure pick ups on the flow divider.

Clarence

[EJS]

Clarence thanks for the reply. That's what we were thinking but wanted to confirm.

Our Mooney is a 1964 M20E. SN 113. The parts manual we have shows some conflicting information. First the older manual we have has a schematic that shows the fuel pressure line coming off the distributor (spider) on top of the engine but that would be low metered pressure not fuel pump pressure. Second it lists a 45.5 inch -3 hose. Obviously that length can't be coming from the spider which brings me to my next question. Both parts manual call out restrictor PN 610013-501 for our serial number. Later serial numbers appear to use PN 610120 which according to Mooney has been replaced by 940178-1. They still sell the -501 part. My question is which one correct? The new part number is nearly twice the price of the -501 and they are both outrageously priced for a fuel line fitting. Does anyone have one of these they would sell or know where to get a used one?

[tony]

[tony]

This is a new servo.  You will see a plug with safety wire.  The plug needs  be removed and replaced with a special fitting that has a pin hole in it.  Clarence can elaborate.  

[carusoam]

Great photo, Tony!

We don't often get to see that out in the open.

Best regards,

-a-

[Guest]

The fitting is likely a standard industrial fitting which has been modified with a small restrictor.  They are as you have found, quite expensive.

I don't have the IPC for your serial number here at home so I can't help you with correct part number.

Clarence