Hey Gents,

I just installed a totally new fuel system in my 72 Cutlass - from TanksInc. New tank, fuel pump lines etc.

Thing is, my stock gas gauge doesnt work correctly now, where an empty tank read 1/2 full on my gauge. Basically the gas gauge is pegged as full until half the tank is empty then the gas gauge starts to move down, but right now 1/2 tank on the gauge is an empty tank in reality. At least I know this much.

My friend that owns a shop said the resistance did not seem to be matching with GM specs or something, not sure how that works. He couldn't seem to fix it and it didnt seem to be an actual problem with the sending unit or float in the tank mechanically itself.

Is this easy/common fix? First for me and I'd love to get the problem solved lol.

 

 

Sounds like the arm on the sender is adjusted wrong. The sender description says it's a 0-90 ohm, which is correct.

 

I’ve been there before. EXACT same problem. The float arm wasn’t adjusted properly. When I first got this car, I threw some money at it in the form of a new fuel system and Fitech. Hired the work done. Picked up my car with “1/2 tank of gas.” Car died on the way home. I just knew for sure that the Fitech had a problem. Finally figured out that I was actually out of gas, Boy was I pissed.
So….. eventually took it back, they dropped the tank, adjusted the arm, life was good. Sort of. Now I have the “floating needle” syndrome on the gas gauge. When the fuel sloshes, so does the gauge.

Solution: Get rid of the float arm and buy a floatless sending unit.

https://www.tanksinc.com/index.cfm/p...rod/prd346.htm

 

Thats what I figured was the problem!

TanksInc replied to me this morning "It sounds like the pivot point on the sending unit is to deep in the tank. When the pivot point is set at the bottom instead of the middle the gauge will behave in this manner."

Ironic thing is, HE was the one who pre-installed everything in the tank for me for an added cost so I wouldn't have to. LOL.

 

Well, I know what one of my winter projects is going to be now!!!

I have had the Holley sniper EFI for a couple years, I installed a Tanks Inc fuel tank to replace the original. I didn’t want an external fuel pump. I have never liked the sending unit included with the tank.

My wife and I drove the Olds to St Ignance last month for their annual car show (even with the lousy weather had a great time) this was the first long distance trip with the EFI. I noticed that after a fuel fillup, you could drive 100-125 miles before the fuel gauge started to move. I would stop at 3/4 tank to refuel, then stopped again at 1/2, next one is 1/4, etc. I found that with the gauge showing around 1/8th, it took 17 gallons to refuel. Zero safety margin. With the fuel gauge showing empty, it would really
be empty!!!

I did drop the tank the first winter after the EFI swap just to verify the sender was installed correctly. I also don’t like the”floating” needle this sender has.

 

Ironically, I haven’t implemented the fix yet. I decided that the next person to drop the tank will be me. It’s on jack stands now, so it’s happening pretty soon. The “pros” are usually more interested in your money than anything else.

I already have the new sending unit and new guts for the fuel pump. Why new guts for the fuel pump? Your standard entry level fuel pump will run at 100% duty cycle (full blast) at all times, regardless of what fuel amount is actually called for. This also means it’s producing maximum NOISE all the time, which is especially noticeable at idle. My particular Fitech has a PWM (pulse width modulation) feature, that when combined with a PWM compatible fuel pump, it basically turns it into a variable speed fuel pump. Produces less noise and heat. Might as well while I’m at it.

The bad news is that I’ll be on here seeking advice on fuel tank dropping and how to work with AN fittings. 😬.

 

This thread ended up being more informative than I thought - this community is great!

I find it ironic, TanksInc. said the sending unit was installed incorrectly (until they were reminded THEY pre installed it for me for extra cost), then it was a million other excuses). Then I said everyone with the same issues, and preferred and installed the float-less sending unit. TanksInc said they like the ball-float sending unit better than the float-less.

Sounds like I will install the float-less sending unit, as doing the opposite of what TanksInc themselves state seems to be the better way LOL

 

Just to give this horse another hit while it’s down, My first Aeromotive (made by Tanks Inc) EFI tank had the same ball float issue. I had to remove it and bend the arm to get it acceptably accurate. The other thing I notice is that the gauge is much more active than with the OE float, seems about half as buffered. I have that same sender/float in a new tank now.

In case anyone could care or just never thought about it, I always take a new tank to the radiator shop and have him solder in a 1/8” or 1/4” NPT bung at the low point of the tank so I can drain fuel out for whatever reason. This was helpful with my first gen EFI tank as it was in and out of the car for the float situation and investigating starvation problems that unfortunately required being replaced by a new design tank which solved the issue.

 

Sounds like this is a very common problem!

 

So did those guys at Tanks Inc mention WHY they prefer the arm / ball float? THEY were the ones to recommend the float-less unit to me. If the latter has gremlins of its own, then I’m gonna be pissed. I suspect they normally package it with the ball float, because it hits a lower price point. I like the idea of an easy drain port for servicing. Just like transmissions should have them too.

 

"I personally prefer the arm type senders as they tend to be more accurate when setup correctly, but the tube senders are much easier to install." - TanksInc

 

Is there a resistor on the back of your gauge still?

 

Hopefully this has been resolved after three years...

 

More detail?