Changing Fuel Jpi 700: Step-By-Step Guide To Upgrading Your Aircraft

The JPI EDM-700 is a fuel flow monitoring feature that can be added to the JPI EDM 700/800 series. The EDM-700 series is a piston engine-monitoring instrument that can monitor up to 24 critical parameters in your engine. The fuel flow transducer measures the flow of hydrocarbon fuels such as gasoline, kerosene, and #2 diesel fuel. The transducers give repeatable signals on gasoline across a 100 to 1 flow range down to 0.3 GPH. The JPI EDM-700 is a cost-effective solution for monitoring your engine and can be used to monitor engine temperatures and voltages, adjust the fuel/air mixture, and diagnose engine malfunctions.

Fuel flow transducer issues

The JPI EDM 700 Fuel Flow system is a cost-effective solution for monitoring your engine. However, there are some common issues that users may encounter with the fuel flow transducer.

One issue is incorrect fuel readings. This can be caused by a number of factors, including an incorrect K-factor, turbulence caused by an angled fitting, or incorrect wiring. To resolve this, users should check the K-factor and ensure that the wiring is connected correctly, with the red wire for power, the black wire for ground, and the white wire for the signal. Additionally, the transducer should be installed with a straight fitting to avoid turbulence that can affect the readings.

Another issue is a low fuel flow reading, which can be caused by the transducer being installed backwards. To resolve this, users should check the installation and ensure that the "in" and "out" ports are correctly oriented, with the "in" side coming from the fuel control and the outlet going to the manifold valve on top of the engine.

Other potential issues with the fuel flow transducer include leaks and damage caused by incorrect mounting. To prevent leaks, it is important to ensure that the mating surfaces of the NPT unions are machined accurately. For sealing NPT threads, users can use Loctite or fuel lube, but should avoid Teflon sealing tape as it can break off and plug the line. To avoid damage to the transducer, it should not be hard-mounted to the engine, as vibration may damage internal parts or cause erratic readings. Instead, users should follow the recommended torque specifications for tightening fittings and ensure that there is no bend in the line within 6 inches of the transducer.

Incorrect wiring

First, confirm that the wiring is connected correctly. The JPI EDM 700 has three wires: a red wire, which is power; a black wire, which is ground; and a white wire, which is the signal. If these wires are not connected correctly, it can lead to inaccurate fuel flow readings.

Next, check that the transducer is installed in the correct direction. The ports on the transducer are labelled "in" and "out", and the fuel flow direction is critical for accurate readings. The "in" side should be connected to the fuel control, while the "out" side should go to the manifold valve on top of the engine. If these are reversed, it can lead to incorrect fuel flow readings.

Another potential issue is the fitting into the transducer. This needs to be a straight fitting. Turbulence caused by an angled fitting can cause inaccurate readings. Ensure that there is no bend in the line closer than 6 inches before or after the transducer. Additionally, make sure that the transducer is mounted horizontally with the three wires facing up. This ensures that the rotor is in the proper orientation to the flow of fuel.

If you have a carbureted engine, the transducer should be installed before the carburetor. If the transducer is higher than the carburetor, an anti-siphon loop is necessary to prevent fuel from flowing back into the transducer. For injected engines, the transducer should be installed between the engine fuel pump and the servo regulator.

Finally, check that the wiring for the transducer is not routed with or adjacent to ignition wires, alternator wires, spark plug leads, or cabin heater ignition wires. This can cause electrical interference and lead to inaccurate readings.

Fuel readings incorrect

If you're experiencing incorrect fuel readings with your JPI 700, there are several potential causes and solutions you can try.

First, check that the transducer is installed correctly. Confirm that the “IN” and “OUT” markings on the transducer are oriented in the right direction. The “IN” side should be connected to the fuel control, while the “OUT” side should go to the manifold valve on the engine. Also, ensure that the transducer is installed horizontally with the three wires facing up. This is important for the proper orientation of the rotor in relation to fuel flow.

Second, check your K-factor. The K-factor is a calibration setting that can affect fuel flow readings. Refer to your installation manual for instructions on setting the correct K-factor.

Third, inspect your wiring. The JPI 700 has three wires: red (power), black (ground), and white (signal). Ensure these are connected correctly. Additionally, check that the wiring is not routed with or near ignition wires, alternator wires, spark plug leads, or cabin heater ignition wires, as this can cause interference.

Fourth, pay attention to your fittings. The use of angled fittings can cause turbulence, which can affect fuel readings. Ensure that the fitting into the transducer is a straight fitting to minimize turbulence. Also, do not use Teflon tape or thread sealant compound on the transducer threads, as this can void the warranty and potentially cause transducer failure.

Finally, other potential issues could be related to air entering the system, incorrect fuel units, or issues with the transducer itself. Check for leaks or cracked o-rings, especially at the selector valve. Ensure your fuel units (e.g., gallons, pounds, liters, or kg) are set correctly. If issues persist, you may need to test or replace the transducer.

Remember to consult your installation manual and seek professional assistance if needed.

Fuel flow monitoring feature

The JPI EDM 700 is a piston engine-monitoring instrument that can be equipped with a fuel flow monitoring feature. This feature allows you to monitor the fuel flow in your engine, helping you to improve fuel economy, reduce maintenance costs, and extend engine life.

The fuel flow monitoring feature for the JPI EDM 700 is an optional add-on that can be installed during the initial setup. It is the only graphic engine monitor that comes with a complete fuel flow system, freeing up valuable panel space in the cockpit. The fuel flow data is displayed both digitally and in analog format, providing a clear and intuitive reading of the engine's performance.

To ensure accurate fuel flow readings, it is important to set the correct "K factor" in the unit. The K factor is a calibration setting that ensures the fuel flow rate is measured accurately. Incorrect K factors can lead to significant discrepancies in the fuel flow readings. Additionally, the direction of the flow transducer is critical. If the transducer is installed backwards, it will result in incorrect fuel flow readings.

The JPI EDM 700 fuel flow monitoring feature offers a comprehensive set of tools for monitoring fuel usage and engine performance. With this feature, pilots can access critical data during flight, aiding in decision-making and optimizing the aircraft's performance.

Fuel flow transducer placement

The JPI EDM 700 is an engine-monitoring instrument that can be used to monitor up to twenty-four critical parameters in your engine, four times a second. It is fully automatic and allows the user to select any readout. The EDM 700 can be used to monitor engine temperatures and voltages, adjust the fuel/air mixture, and diagnose engine malfunctions.

The Fuel Flow Transducer is an optional feature that can be added to the EDM 700. The placement of the Fuel Flow Transducer depends on the type of engine in the aircraft:

• For carbureted engines, the transducer should be installed before the carburetor. If the transducer is higher than the carburetor, an anti-siphon loop should be installed in the line that peaks higher than the transducer.
• For injected engines, the transducer should be installed between the engine fuel pump and the servo regulator. For injected engines with vapor return lines, the transducer should be installed between the servo regulator and the flow divider (spider).

It is important to note that the transducer should be mounted horizontally with the three wires up. This ensures that the rotor is in the proper orientation to the flow of fuel. Additionally, there should be no bend in the line closer than 6 inches before or after the transducer. The transducer should not be hard-mounted to the engine as vibration may damage the internal parts or cause erratic readings.

When installing the Fuel Flow Transducer, it is important to use the correct fittings and avoid using Teflon tape or thread sealant compound as this will void the transducer warranty. The recommended fittings are:

• #4 AN816-4 Steel 1/4 NPT
• #6 AN816-6 Steel 1/4 NPT
• #8 AN816-7 Steel (JPI only has -7 1/4 NPT)

Frequently asked questions