Fuel gauge doesnt work on my 1997 Beaver Monterey with 3126 e emgine

[Desertrat]

Hi,

I am new to this and i just purchased used  1997 Beaver Monterey 36ft mtr hm with 3126e engine. Has 46k miles and the fuel gauge is not working . Previous owner said he sparked something
when messing with batteries for solar system and noticed gauge quit working. So as part of purchase he was to get gauge working well its not and i am needing help on steps to take to diagnose
what the problem is.

Thank you
Rick

[WallyNM]

We had a similar problem and we had to replace the gauge cluster.

[David.e.atherton]

Hi have to agree with Wally, would replace gauge assembly.would be my first choice.
Plan number 2 to fuel  tank and locate two wires going to gauge in tank and should be
Ground to screw holding gauge in fuel tank check ground to make sure there is a good
ground and check gauge for movement on needle. If nothing happening apply 12 volts to other wire if nothing or movement replace like Wally indicated. If traveling when you fill up
Check your miles traveling you will be getting 7 mpg and you should have a 100 gal fuel
tank. Than wait till you are in your home court for repair where you can control cost.
Ask Dave, Dave Atherton Retired Cat Mechanic

[Desertrat]

Thank you for your replys. Where can i purchase the gauge to replace it? Magnum chassis.

Thank you
rick

[Brett Wolfe]

Hopefully, someone else with that vintage Beaver/Magnum chassis will have details.

BUT, before doing that you do need to diagnose the problem-- you want to insure that it is not a loose wire or sending unit problem before ordering and installing a new gauge or gauge cluster.

Said another way, do not ASSUME that is is the dash gauge at fault-- prove it first.

[Desertrat]

Excellent advice and thats just what i will do.

Thanks Rick

[ziggyh]

Most fuel gauge circuits of that vintage can be diagnosed by disconnecting the sender wire, with it disconnected the gauge should go to one extreme, with it grounded it should go to the other. If there is no change then the next thing to check is the wire from the sending unit to the gauge. If the wire is ok then the circuits to the gauge is the next step. There will probably be 2 more terminals in the gauge one will be a ground the other is a power supply. The power wire is usually a lower voltage some are around 8 volts this comes from a small voltage regulator for the gauge. A voltage regulator is used instead of battery voltage so that the gauge does not fluctuate as the battery voltage does when driving. Some gauge circuits share that voltage regulator with other gauge so other gauge would not be working if it was a problem.

Another problem that can cause gauge so to be inoperative or read incorrectly is if diesel fuel has leaked through the terminal or wires on the sending unit, diesel fuel becomes conductive as it absorbs the moisture in the air, cleaning with brake clean would only be a temporary fix.

Checking the sending unit, they should have a resistance of 20 to 120 ohms depending on the position of the float. Note: depending on the type of float used they can saturate with fuel and cause incorrect readings or read empty if they are sunk.

the sending unit may have 1,2,or 3 wires on it. A common ground, the fuel level wire and sometimes a power wire for an internal lift pump.
 If the resistance spec is known the accuracy of the gauge circuit can be checked by putting a resistor of the approximate values between the gauge wire and ground wire.

[ziggyh]

here is a picture of a balanced coil type gauge circuit.


If your fuel gauge only has 2 terminals on it, it is a bi-metal type.  The checking procedure is pretty much the same, except you will not have a ground terminal on the gauge, just a power terminal, and a terminal for the sending unit wire.