1996/04/15 Caterpillar

Reference: Tool Operating Manual, Using The Caterpillar Fuel Flow Monitor System, SEHS8874-01.

On some Caterpillar engines, it may be difficult to accurately measure return fuel flow because of air bubbles in the return fuel. The air bubbles in the fuel cause the turbine flowmeter to read higher fuel flow rates than actual.

Caterpillar recommends installing a 138 kPa (20 psi) check valve (B) at the outlet of the flowmeter (A) reading return fuel flow. See the illustration. The check valve will prevent any air bubbles in the return fuel flow from expanding while the fuel is flowing through the flowmeter. This will result in a more accurate reading of return fuel flow.

The Refererence shows the 4C-9759 Return Flowmeter Group (small) and the 4C-9761 Return Flowmeter Group (large).

The following parts are required to install a 138 kPa (20 psi) check valve on the outlet of the sight glass on the return flowmeter groups.

Identification of components in a typical fuel system. Caterpillar Return Fuel Flowmeter Group (A). Check Valve (B). Primary Fuel Filter (C). Caterpillar Supply Fuel Flowmeter Group (D). Fuel Transfer Pump (E). Fuel Filter (F). Fuel Supply Line (G). Fuel Injection Pump (H). Fuel Return Line (J). Diesel Fuel Tank (K).

Parts Needed For 4C-9759 Return Flowmeter Group (small)

* Check Valve (Parker Hannifin Part No. C820S-20)

* No.8 JIC female fitting (Airway Part No. 6402-0808-0)

* No.8 JIC male fitting (Flowdar Part No. RAC-1000-8) on the outlet of the sight glass on the 4C-9759 Return Flowmeter Group (small).

Parts Needed For 4C-9761 Return Flowmeter Group (large)

* Check Valve (Parker Hannifin Part No. C1620S-20)

* No.16 JIC female fitting (Airway Part No. 6402-1616-0)

* No.16 JIC male fitting (Flowdar Part No. RAC-1000-16)

The preceding non Caterpillar part numbers are available from: