Fuel Sending Unit way way way off

[Doogie]

I replaced my fuel sending unit with one from DMC and it never reads right. Ever.

When I fill it up, (stopping after first "click" of the handle) it will usually rise up to about 3/4 or even 7/8 reading, and I'm fine with that.

But, I can drive about 50 miles, and it will read about 1/2 tank. 50 miles? 1/2 tank? wow, that's some really bad MPG!

My took the car to work the other day. The night before, I drove down to the gas station and topped it off, and reset the odometer. Took it for a short cruise, about 18 miles, and she drove it the next day. Total Mileage? 62 miles, and the gauge was on empty when she got home, and the low fuel lite was on. 62 miles?!

I took it down to the gas station, put 3.2 gallons in it before the first click.

Seems like my new fuel guage is defective. waddya think? just get another new one?

Doogie

[DeLorean03]

Gotta be more specific with us, Doug. Is it the $400 combo, or the $100 sender?

[Doogie]

Gotta be more specific with us, Doug. Is it the $400 combo, or the $100 sender?

Oops, sorry. The $100 job. Did I hear from Dave H. correctly that after you replaced yours setup with the combo unit you gave him your leftover sending unit? Did it work as far as you recall? He offered it to me to try, I might just take him up on that...

[DeLorean03]

Yes, you heard correctly. Mine was pretty good. Whatever the gauge read, the tank had 1/4 more than that. For example, if the gauge read half a tank, it really had 3/4 a tank. Was good for a solid 9 yrs like that!

[WelmoedJ]

I replaced my fuel sending unit with one from DMC and it never reads right. Ever.

When I fill it up, (stopping after first "click" of the handle) it will usually rise up to about 3/4 or even 7/8 reading, and I'm fine with that.

But, I can drive about 50 miles, and it will read about 1/2 tank. 50 miles? 1/2 tank? wow, that's some really bad MPG!

My took the car to work the other day. The night before, I drove down to the gas station and topped it off, and reset the odometer. Took it for a short cruise, about 18 miles, and she drove it the next day. Total Mileage? 62 miles, and the gauge was on empty when she got home, and the low fuel lite was on. 62 miles?!

I took it down to the gas station, put 3.2 gallons in it before the first click.

Seems like my new fuel guage is defective. waddya think? just get another new one?

Doogie

Your fuel consumption of 3.2 Gallon for 62 Miles seems a bit high.
This calculates for 19,375 Miles per Gallon.

However there's more to consider when trying to calculate fuel consumption.
Consider acceleration, average speed, city vs highway, outside temperature, long idling etc.

Go and keep record of miles and refill quantity each time you're going to fill up.
Fill up all the way until first click (as you did before).
Use your Mileage counter to track the Miles between fills.
After a year you will have a more accurate overall fuel consumption pattern.

A fuel sender/gauge is only a simple means to let you know about the contents.
Never trust it as the instruments are not calibrated.
Use your day trip counter to give you a more accurate signal when it's time to look for a gas station.

If the fuel consumption pattern over time changes significantly, there's work ahead: either pre-emptive maintenance, of bigger issues.
Therefore keeping track of fuel consumption is a great help to Judge your car's condition.

BTW: If you're eager to know your car's fuel consumption over time, I'll have an Excel sheet that can help you.
For reference, my car 'dwells' between 28 ~32 Miles per Gallon and I do demonstrate (engine sound at shows) and regularly drive higher speeds (up to 120 MpH), also over longer distances.
PM me if you want to have a copy of this fuel consumption sheet.

[NightFlyer]

my car 'dwells' between 28 ~32 Miles per Gallon

Is that imperial gallons, or us gallons?

[WelmoedJ]

Is that imperial gallons, or us gallons?

US Gallons (or 3.8 liters in a Gallon).

[Silverbullet]

Well,

IF you ever do the new combo unit...FYI, it works GREAT!...

Craig

[NightFlyer]

US Gallons (or 3.8 liters in a Gallon).

That's great economy you're getting - especially if you're idling and city driving a lot!

[refugeefromcalif]

Your fuel consumption of 3.2 Gallon for 62 Miles seems a bit high.
This calculates for 19,375 Miles per Gallon.

19,375? LOL.

I drive my D as a Daily Driver, (When it's not Pouring Rain).

I drive 7.8 miles to work One way. The Highway/main part of that is 6 miles @ 65MPH.
I go out for lunch everyday and the car stays on while I eat in comfort, (30 minutes with the A/C running on MAX).
I get between 19-21 MPG with the D right now. My Grand Caravan gets 14-15 MPG under the same conditions.
That's one reason I drive the D as much as possible. :biggrin:

George

[dvonk]

Your fuel consumption of 3.2 Gallon for 62 Miles seems a bit high.
This calculates for 19,375 Miles per Gallon.

19,375? LOL.

many europeans use a comma instead of a dot in decimal numbers.

[Henrik]

I have the old style fuel sending unit. When I have it out of the tank (with wires still connected) and I turn it upside down the float goes all the way to the top and the gauge pegs out, showing completely full. When I turn it right side up the float falls to the bottom and the tank shows completely empty, so it is working OK.

But when I install it it nevers shows less than 1/4 tank or more than 3/4 tank. I am suspecting that maybe the gasket is too thick so that it covers up the tube's vent hole at the top and therefore not allowing air to enter-exit the tube (ie the float is not moving to the extreme positions properly)... If so, a thinner gasket is the way to go. Drilling additional holes in the tube might be a bad idea as the float may snag on the burrs on the inside.

Does anyone have any thoughts on my issue?

[Jack]

I get between 19-21 MPG with the D right now.
That's about my average also.
I take the claims of anything over 25 mpg with a huge grain of salt.
20731

This is the first I've seen a claim of over 30 MPG. :jawdrop:

[dmc6960]

That's about my average also.
I take the claims of anything over 25 mpg with a huge grain of salt.
20731

This is the first I've seen a claim of over 30 MPG. :jawdrop:

I got lots of witnesses who can confirm I get over 30mpg on the highway. Averaged 31mpg on the drive to DCS 2010, and on the flat (non-mountainous sections) of the drive to DCS-2012 I got anywhere between 30-32mpg.
City driving is anywhere between 20-25mpg.

Back when my engine was stock, I could still pull 27-29mpg highway.

[Grover]

It's all about the speed and the state of your engine tuning. I got 31 mpg from Albany, NY to Morristown, NJ, BUT I never went above 65mph. It can be done. (This was before all of my engine work).