Fuel Flow Transducer - New Installation

[Janat83]

Hello Mooniacs

I recently upgraded my JPI EDM700 so it shows Fuel Flow function, my main mechanic is sick and I had to take it to a new mechanic who installed the Fuel Flow Transducer as shown in pictures, do you think it's good installation, and is it normal to lay the transducer sleeve down on the bottom like that. 

I also noticed that fuel flow fluctuates rapidly +/- 1 GPH approximately on max power for take off , is that normal to see the Fuel Flow fluctuating like that?? 

The airplane was normal on runup, I only noticed delay in fuel pressure when I turn on the auxiliary fuel pump. 

Thank you in advance for your helpful thoughts. 

MOUSTAFA JANAT 

Edited September 7, 2019 by Janat83

[Guest]

The 2 hoses could stand to be replaced with shorter lengths.  Also the clamp on cylinder 4 exhaust stack is wrong.

Clarence

[Yetti]

Looks half ass.

When the black ty wrap fails where will that hose go (hint something really hot)  Adel cushion clamps back to back would be better.

Firesleeve does what good if the ends are not secured (the piece over the transducer)

Could be routed better.

Wiring should not be just hanging out just flapping around.  Move it around enough and it will break the wires.   secure it

What's that white stuff on the hose connection at the carb?   Most of these fittings are supposed to be no sealant type connections.

The wiring bundle looks like sensor wires should not be touching the carb.  Nor should it be hanging by the icing probe in the carb.

Some fuel transducers instructions suggest that it should be level or close to level.  You might want to check.

 

 

[Yetti]

Second to bottom pic.  Fuel line should not rub on the cowl flap.

[DXB]

Looks totally sloppy in comparison to my install - sorry don’t have a pic handy - will try to get one.

My hoses are measured to allow it to be carefully suspended away from everything else - I think some rigid ones were used also to immobilize it completely- will have to look - the transducer itself is fixed in place like a rock even though it is not ziptied to anything. Why in the world would someone simply lay such a critical component on top of the cowl flap? My ends of the firesleeve are closed off with safety wire (what good does the sleeve do with the ends gaping open?).  The electronic connector for mine is carefully routed and secured to the hoses and engine mount, not flopping in the breeze like yours.  

Also the fluctuation in flow is not normal at all- an artifact of the sensor not being properly secured maybe?

Edited September 7, 2019 by DXB

[MIm20c]

The small FF fluctuations are normal with a carb as it’s filling the float bowl. Looks like some high quality hoses were used. IMO the routing and attachments need to be modified slightly. 

[Browncbr1]

I don’t like how it is routed through probably the hottest area of the cowl.  There is probably enough hose there to just move it around and re-secure high up along firewall behind baffling maybe fixed to the upper motor mount.    Zip tie both ends of fire sleeve closed.   

Occasionally check for blue dye in the fire sleeve.  Especially if your engine misses up high and FF and fuel pressure fluctuate up high.  Although those are self sealing pipe threads, I had to use special sealant. (Not Teflon tape)

[Yetti]

10 hours ago, Browncbr1 said:

    Zip tie both ends of fire sleeve closed.   

 

unless it's a metal zip tie it really does no good to use a nylon one.

[Nukemzzz]

I'm not an AP or IA, however, I know that fuel lines are something that should be taken very seriously.  You are supposed to land right below you as fast as possible in the case of a fire and hope that the ground is close enough to get there.  

Others have already said what I saw:  Shouldn't touch cowl flaps.  Fire sleeve should be secured on each side of the transducer. 

It looks like the lines purchased were too long and the technician tried to make them work.  It's good that there isn't a high point in line routing.  I think there is an AD on that aspect.

I recommend getting the the install instructions yourself to double check his work.  

[ArtVandelay]

It’s supposed to be mounted horizontally, and mine is secured to the firewall.

Yours looks like it’s at a 30° angle. Don’t know if that’s “good enough”.

[Immelman]

Perhaps its the photos, but the wire harness coming out of the fire sleeve looks precariously close to the exhaust, and does not appear to be secured away from it.

I have an E, so different fuel setup, but when we did my JPI fuel transducer, we removed a single long hose (From engine fuel pump to servo.... I think... memory fuzzy), measured that, and ordered two new hoses, with the fuel flow transducer going between them in a straight-line area, so that the length of the entire new contraption was the same as the old hose we removed. The hoses were all fire-proof. Then the assembly between the two hoses and transducer covered in fire sleeve similar to what you have. Well way from exhaust.

Edited March 2, 2020 by Immelman

[0TreeLemur]

A&P Dave, before he flew west, installed the fuel flow transducer in our C using an elbow and three pieces of hose, not two pieces.   Photos of that are on MS someplace.  

Instructions from From the JPI "Frequently Asked Questions" on their web site say:

1.  Make sure the transducer is horizontal with the wires up.

2.  Be sure there is no bend in the line closer than 6 inches before or after the transducer.

3.  Do not use aluminum fittings.

4.  For carbureted engines, if the transducer is higher than the carburetor, put an anti-siphon loop in the line that peaks higher than the transducer.  We installed it slightly lower than the carb for this reason.

5.  Mounting the transducer between the electric boost pump and mechanical pump is not recommended.

6.  Do not hard mount the transducer to the engine.  Vibration may damage the internal parts and cause erratic readings.

7.  Do not use teflon thread tape.   The big issue with this is that the teflon tape can produce threads that when mobilized, and jam in the fuel system or in the fuel flow transducer turbine.

I'm not an A&P, just an involved and curious owner and PP.  Good luck!

[0TreeLemur]

I found this photo shows the installation mentioned in my previous post.   We bought three hoses and one elbow.   The length of hose from the elbow to the sensor is about 6".   The hose connecting the sensor to the carburetor is about 5" long.   I don't remember for sure, but it seems that the hose coming down from the fuel pump was about to 16" long.   The sensor and the hoses connecting to it all slope uphill towards the carb to avoid the need for an "anti-siphon" loop in the line.   The trick is keeping it all near the firewall, away from #4 exhaust riser,  braced, and not rubbing on the cowl flap when closed.   Also, generous application of high temperature silicone to close the fire sleeve.  Fittings nice and tight with no sealant.  Not an A&P, just showing what my A&P IA approved.  Good luck.

[0TreeLemur]

A closer photo taken the last time I had the cheek cowl off.

 

[jetdriven]

There are detailed drawings In the EDM fuel flow installation manual and its pretty clear 

[carusoam]

Nice pic of the whistle hole in the case vent line too!

-a-

[Aerodon]

It's always a challenge to make a neat installation of the JPI FF Tx.  It helps to have a box full of the various fuel fittings to experiment with straight and 45 degrees out of the gascolator or into the carb.  Then have a hose shop on speed dial to make up hoses exactly to length, with either straight or 45 degree fittings.  I always have straight fittings into and out of the FF Tx, and always get it pretty level as per JPI instructions. The 90 into the FF Tx in the photo above would not meet my standards.  This is necessary for the FF transducer to discharge any bubbles that might be entrained, and also to measure accurately.  Then always band the fire sleeve.  And punch and seal a small hole with RTV for the wires.

It takes a bit of practice and rework to get the hoses to route nicely, and also not induce any side loads on the fittings.  Don't be shy to get it redone to your satisfaction, now or the next annual.

 

Aerodon