fuel guage

Try grounding the wire going to the sender. The gauge should go to full. If not, either you have no power to the gauge or the gauge itself is bad. Use your ohmmeter on the sender (with the (+) wire disconnected) and check resistance to ground. The range (I think) is 240 ohms empty to about 80 ohms full. Also make sure the ground is good. A common problem on these is the float on the sender sinking due to a hole in it. Hope this helps!

Tommy

Hope this helps.

Mark

I"m not sure about the actual ohm readings but the least ohm figure is full and the most is empty on most gauges; however it can be the other way around, doesn"t matter. Some GM autos are that way; you ground the sender wire and they will go empty. The gauge is just like an ohmmeter in that it reads resistance to ground. The sending unit is just a variable resistor. Yes if you leave the ground on the gauge it will ruin it but for an instant, it will not be harmed. Its just a quick check to see if the gauge is working. Been fixing them for about 20 years now like that for what its worth. Thanks for the post!

Tommy

Have a "91 Ford hay truck and the ignition switch located on the steering column broke (literally). Figured out how to and did replace it.

Next thing you know the fuel indication gets irratic. Thought I"d disturbed something in replacing the switch.

Hmmmmm m. Went to the trusty resistor drawer and pulled out several resistors between 200 and 33 ohms. Disconnected the wire from the sending unit, installed the resistors (one at a time) and presto. Gauge works fine. Must be the sending unit. Bought such, replaced, problem gone.

Mark

Got another odd one for ya". Had a Lincoln welder with a Deutz F4L1011F engine come into our shop that customer said was cutting off after about 30 minutes operation. Fixed a fuel leak on it and thought maybe that was it; cranked it up and it ran for 3 hours fine. Two weeks later it comes back with the same problem. Making a long story short, it had a low level fuel function built into the engine controller. Being a diesel, at about 1/4 tank the controller shuts the engine off so you don"t run it out and have to bleed it. You can turn the switch off and restart it and get another 30 minutes out of it to finish a job. We were unaware of this on the first repair, but it also had over 3/4 tank of fuel (it would never shut off like that). Second time in it had a bit less than half but the fuel sender was bad and would send a low fuel reading to the controller. I pulled the float up by a wire and it ran 4 hours non-stop. And they wonder why techs have no hair!!!!! !!!

Just for laughs, the fuel gauge doesn"t work on my 240 MF either; I just take the cap off and look in the tank! LOL, LOL, LOL

Tommy