Adjusting an Autometer Fuel Guage

[fng]

Ok, with the help of a motorcycle jack and occasionally my wife, I got the fuel tank installed. As part of the rebuild I put in a new sending unit from autometer that matches the guage I installed in the cluster.
I carefully followed the instructions included in the box as for the proper adjustment of the arm and stem. (The depth of out tanks is 15 1/2 inches deep if anyone cares) Got it all hooked up, grounded and installed. Poured in 4.8 gallons and looked on the guage....read zero. Decided to do some trouble shooting, checked all the connections, and decided to try 5 more gallons. Ok, poured that in (now approx 9 gals onboard) checked the guage and it now reads 1/4 tank. DANGIT!
Without having to pull out the cluster does anyone know if the guage has some kind of adjusment screw on the back? If not then I guess I'll have to drop the tank and pull out the "sealed in" sending unit and make adjustments from there huh? Anybody got any ideas before I have to do all that?

[Binford]

The 1/4 tank reading is about right, eh? So it's just not reading as it nears empty then?

Maybe I'm just tired tonight...

[fng]

My thoughts are if it has 9 gals, it should read about 1/3rd of a tank. Providing the tank is 28 gals that is.

[fisherman]

My experience with gauges and sending units are that none are really dead on accurate. If you fill to half a tank and get somewhere near half reading, I would then fill it up and see what you get. It seems to me most gauges and sending units even on newer vehicles are seldom dead on. If you get an accurate reading when full and almost empy I would probably be satisfied. It would suck though to run out of fuel with the gauge above empty. I hope my new fuel sending unit will be accurate. Good luck and keep us posted.

[white433]

Don't worry so much about dropping that tank! For one reason or another, we kept having to drop ours, after seven or eight times it gets easy.

[LuckyPabst]

Were you able to adjust the sender completely for the depth of our tanks? The 715 tanks are very deep in the world of gas tanks. With my S-W sender (they make two - a "deep" and "shallow" version) it would only adjust out to within about 1" of how deep the tank is - it had a max tank depth of 14-1/2" or something like that. I just figure that when my gauge reads "E" that I still have a reserve left so "E" dosen't really mean "emergency" and I keep a little fuel on the EFI pump at all times.

Chris

[Barrman]

My Auto Meter fuel gauge with a Chevy sending unit reads about the same. It lives on full for about 60-80 miles. Gets to 1/2 tank by 120 miles on a full tank. By 160 miles on a tank, it is layed over at empty. I can normally stuff between 14-20 gallons back into the tank at that point.

I have bent the float arm everytime I have had the tank out for something to try and make it more even and it really doesn't change much. When you think about the fact that every inch is about 2 gallons, it would take a lot of bending to make a signifigant difference anyway.

Also, I wouldn't really consider 28 gallons to be your usable fuel supply. It takes a little more than 1 gallon in the tank just to get fuel to the level of the stock pickup tube. That is with the tank level and still. Realistically, you can figure 2-3 gallons still in the tank and you might run dry at the engine. I have a fuel psi gauge on my truck and rely on it when the gauge is laying over at empty with that last 10 gallons or so still in the tank. When I drop to 0 psi on acceleration and get normal psi back once at a steady speed, I know I am down to about 4 gallons.

[fng]

Wow, good info to have. I was thinking about it a little more and I agree that when it reads "E" that I will have a built in reserve so to speak.
Really considering the big picture I'm just glad it reads anything at all!!!! I'd hate to have gone to all that trouble and expense to have a dead guage.

[BCOWANWHEELS]

sending unit is hitting bulkhead in tank i bet.

[fng]

Actually I allowed for that during installation and rotated the stem (not the arm) to a position that would allow for clearance. I haven't filled the tank completely to check for a full indication but like I said before, as long as the guage reads something, I can adjust.