Fuel transducer routing in an M20C

[Dave Morris]

The early Mooney cowl is legendarily tight. I want to have a JPI fuel flow transducer mounted ahead of the carb, and both JPI and EI say to mount it on a length of hose, not directly to the carb. And if the transducer ends up higher than the carb, there's even supposed to be an upward loop in that hose.

Do any of you have photos of a proper (working!)  installation that I can use for reference when I talk to my A&P about creative routing options? (I think my A model actually had more space in the cowl to route those giant hoses!)

 

[Prior owner]

Not sure whether these will help, but here is mine

[DanM20C]

It's difficult to follow the directions from JPI and make it work in a C.  My installation worked well but I didn't have a powerflow in the way.  Things look extra tight for you.  If you add 15+ inches of fuel line and some creativity you should find room lower in the lower part of the cowl. 

Cheers,

Dan

 

[carusoam]

Read the transducer installation instructions carefully...

They can be very sensitive to 90° elbows close by....

The sensors prefer long straight entries and exits.

Turbulent and laminar flows are meaningful inside pipes and hoses as much as they are around wing surfaces...

My FF sensor is mounted across the firewall(?) allowing lots of entry and exit distance... often, engineers use a ratio of 10:1 length to diameter to describe needed entry and exit lengths...

Did the instructions say to avoid 90° elbows or changes in pipe diameter close by?

The oddity of these instructions is they may get by at low flow rates, but their errors may show up later at higher flow rates...

This often makes it very difficult to get a good working k factor...

PP thoughts only, not a mechanic...

Best regards,

-a-

[Guest]

3 hours ago, carusoam said:

Read the transducer installation instructions carefully...

They can be very sensitive to 90° elbows close by....

The sensors prefer long straight entries and exits.

Turbulent and laminar flows are meaningful inside pipes and hoses as much as they are around wing surfaces...

My FF sensor is mounted across the firewall(?) allowing lots of entry and exit distance... often, engineers use a ratio of 10:1 length to diameter to describe needed entry and exit lengths...

Did the instructions say to avoid 90° elbows or changes in pipe diameter close by?

The oddity of these instructions is they may get by at low flow rates, but their errors may show up later at higher flow rates...

This often makes it very difficult to get a good working k factor...

PP thoughts only, not a mechanic...

Best regards,

-a-

You beat me to it again.  I was going to say the same thing regarding 90 degree elbows on flow transducers.

Clarence

[0TreeLemur]

10 minutes ago, M20Doc said:

You beat me to it again.  I was going to say the same thing regarding 90 degree elbows on flow transducers.

Clarence

Here is a photo of the fuel flow sensor we installed in my '67 C.  Sensor is inside the big firesleeve, about 6" downstream from the elbow.   Seems to work fine.   The hose coming down from the engine-driven fuel pump was spec'd a bit long to make sure that the run through the meter slopes upwards towards the carb. 

[salty]

I did mine remarkably similar to Fred. The only difference is I mounted it on a stand-off on the firewall. 

 

[47U]

Dave,  I found this photo on the internet when I was researching my own E.I. red cube install a couple years ago.  I’m not sure how far forward in the cowl your exhaust downtubes extend, mabe this location won’t work for you, but the fuel line routing looks similar to yours and this xducer doesn’t have any 90 degree elbows.  Again, I found this on the internet so cannot vouch for its ultimate success.  Good luck with your install... Thomas

 

 

[Heloman]

I found the only way I could meet all the requirements of the JPI instructions, was to route it behind the oil sump with straight lengths of fuel line on each side using two 90 degree fittings before and after the required straight sections, than it loops back to the carb, seems ridiculous but I don't believe any other way fully meets all requirements in a less ridiculous fashion. You kind of need to make your own fuel lines upon install to work this mess out somewhat cleanly.Too bad we can't mount the flow meter vertically...

Edited December 18, 2018 by Heloman

[jetdriven]

On 12/5/2018 at 7:47 PM, salty said:

I did mine remarkably similar to Fred. The only difference is I mounted it on a stand-off on the firewall. 

 

 Is that plastic string holding the firesleeve on? You get the purpose of firesleeve, right? 

[salty]

9 minutes ago, jetdriven said:

 Is that plastic string holding the firesleeve on? You get the purpose of firesleeve, right? 

That was redone properly with clamps 

[mike20papa]

I couldn't figure how to configure installation under cowling to meet EI's spec, so opted for under floor, just down stream of elec. pump.   Required moving pump, forming new fuel lines, but it's a solid mounting.  Joe