Diagnosing the Fuel Gauge

Tag: diagnostics fuel gauges

SPECIFIC TEST PROCEDURE FOR FUEL GAUGE USED BY CATALINA YACHTS

(Other systems may use a different procedure.)

There are FOUR components in the fuel gauge system on Catalina Yachts and therefore four possible sources of fuel gauge problems.

This article will explain the testing procedure for this system.

1 - The FUEL GAUGE in the engine control panel may be defective.

TEST PROCEDURE :

• Disconnect PINK sender wire from "S" terminal on gauge.
• Turn on ignition switch. Pointer must deflect to extreme left.
• By temporarily shorting together the "S" (sender) and the "G" (ground) studs, pointer must deflect to the extreme right.
• Re-connect the PINK sender wire to the gauge after the test.

2 - The PINK SENDER WIRE may be DISCONNECTED from the sending unit at the tank or SHORTED TO GROUND.

TEST PROCEDURE:

• Disconnect PINK SENDER WIRE from terminal on sending unit in tank.
• Attach pink wire to a KNOWN GROUND, such as engine block or battery NEGATIVE.
• DO NOT ASSUME THAT FUEL TANK IS GROUNDED.
• Turn on ignition switch.
• Pointer must deflect to extreme right, as in previous test.
• Disconnect pink wire from ground.
• If pointer STILL deflects to extreme right, pink wire is GROUNDED at some point between the sender and gauge.
• Check ALL connection points on pink wire or replace the entire wire.

3 - The BLACK GROUND WIRE may be DISCONNECTED from the sending unit at the tank or NOT GROUNDED at the other end.

TEST PROCEDURE:

• If the gauge tests "GOOD" and PINK wire tests "GOOD" attach pink wire to the black GROUND wire on the sending unit at the tank.
• If pointer does not deflect to right (as in test above) the black wire is NOT GROUNDED.
• Follow the black wire from the sending unit in the tank and make sure it eventually CONNECTS TO GROUND.

4 - The SENDING UNIT in the tank may be defective or the wrong unit may have been installed.

TEST PROCEDURE:

• If the gauge tests "GOOD", the PINK wire test "GOOD", and the black GROUND wire tests "GOOD" the sending unit in the tank is defective or the "WRONG" unit may have been installed.
• The "CORRECT" sending unit has a specification of:

STEWART WARNER, 240 TO 33 OHMS RESISTANCE

There are several other resistance specifications available but those sending units WILL NOT WORK in this application.

FUEL GAUGE TEST PROCEDURE

PANEL DEPARTMENT April 22, 2003

* WHITTIER, CA. 90601 * * SEAWARD PRODUCTS *

Information provided by Jamie Pett