inaccurate fuel gauge

[bagpiperjosh]

anyone else have an inaccruate fuel gauge on their IDI? My gauge was almost on E when i tried putting a wmo blend in there, and i only got about 12 gallons at the very most before it overflowed out of the filler neck, lol. and this was the front tank... when i started the truck it was just a hair below the full line.. is there a tech article for a fix for that?

 

[icanfixall]

Not really a good repair for that. Most trucks suffer from this issue. When I first got my rig I would run it out of fuel and switch tanks. Felt I was not harming anything doing that. Every refill was around 12 gallons... Made me think I had a 12 galon tank. Then later years I found out the shower head tank suction had broken off and thats a commone issue with these tanks. Running out of diesel with a 1/4 tank of holly fuel left in it was tuff to handle. So I fixed that with some fuel hose on the end of the tank pickup. Works great now. I still wont suck a tank dry because that can harm the injection pump. Remember the fuel lubes and cools the pump. My gauges still are way past the full mark when they are full both front and rear... I live with it... I really don't know if replacing the dash gauge or the sending unit will fit this. Maybe others will chime in with what the fix is... I will be watching too.

 

[Thefarmboy21]

Mine sat for 10 years before I swapped the motor now I'm working the bugs out...
Until today, my front tank always showed past FULL and the rear tank would always show past EMPTY. I pulled the front tank because I knew it had fuel and because I was getting air intrusion. Showerhead had disentigraded, but tank had about 8 gallons if fuel so wasn't full by any means. Cleaned the sensor fixed the pickup tube with some 3/8 hose and put it all back in today. Now it jumps back and forth between 1/2 and 3/4 tank when I hit bumps and sometimes just idling. It only has maybe 7 gallons in it so it's still wrong but it's kinda working now I guess. The rear may legitimately empty but by the way the gauge acts I think it a sensor problem.

On another note....after all that, I'm still getting air bubbles somewhere between the front tank and firewall

 

[chris142]

Both of my tanks read full until I have about 3 gallons left then they shoot to empty in just a few miles. I figured this was normal since both do the exact same thing.

 

[MIDNIGHT RIDER]

If, and that is a big IF, the sending-unit is electronically accurate, meaning there are no typical Ford dead-spots along the sweep of the gauge-arm, then it is a simple matter to re-form the float-arms such that the gauge reads dead-on accurate.

I retrofitted the generic J.C.Whitney sending-units into my tanks and bent and adjusted the float-arms until my gauge shows the real story.

The $16 J.C.Whitney sending-unit is light-years ahead of the costly Ford unit, far more durable and way more accurate.

Before, both of my tanks would read way past FULL for a hundred or more miles, then steadily drop toward EMPTY for another fifty miles, and fall way below EMPTY before ever sucking dry.

Now, exactly on "F" is neck-full and "E" is bone-dry.

All it takes are a few measurements; over-all depth of the tank at the sending-unit location and at what exact point of over-all depth measurement the pivot-point of the float-arm resides.

The rest is just length adjusting and bending the arm, such that the float travels the entire available depth, instead of just a portion of it.

 

[ZWilson07]

If, and that is a big IF, the sending-unit is electronically accurate, meaning there are no typical Ford dead-spots along the sweep of the gauge-arm, then it is a simple matter to re-form the float-arms such that the gauge reads dead-on accurate.

I retrofitted the generic J.C.Whitney sending-units into my tanks and bent and adjusted the float-arms until my gauge shows the real story.

The $16 J.C.Whitney sending-unit is light-years ahead of the costly Ford unit, far more durable and way more accurate.

Before, both of my tanks would read way past FULL for a hundred or more miles, then steadily drop toward EMPTY for another fifty miles, and fall way below EMPTY before ever sucking dry.

Now, exactly on "F" is neck-full and "E" is bone-dry.

All it takes are a few measurements; over-all depth of the tank at the sending-unit location and at what exact point of over-all depth measurement the pivot-point of the float-arm resides.

The rest is just length adjusting and bending the arm, such that the float travels the entire available depth, instead of just a portion of it.

Did your float arm stay bent where you initially bent them. Seems like over time they would want to move a little on their own and not stay exactly where you initially bent them.

 

[bagpiperjosh]

If, and that is a big IF, the sending-unit is electronically accurate, meaning there are no typical Ford dead-spots along the sweep of the gauge-arm, then it is a simple matter to re-form the float-arms such that the gauge reads dead-on accurate.

I retrofitted the generic J.C.Whitney sending-units into my tanks and bent and adjusted the float-arms until my gauge shows the real story.

The $16 J.C.Whitney sending-unit is light-years ahead of the costly Ford unit, far more durable and way more accurate.

Before, both of my tanks would read way past FULL for a hundred or more miles, then steadily drop toward EMPTY for another fifty miles, and fall way below EMPTY before ever sucking dry.

Now, exactly on "F" is neck-full and "E" is bone-dry.

All it takes are a few measurements; over-all depth of the tank at the sending-unit location and at what exact point of over-all depth measurement the pivot-point of the float-arm resides.

The rest is just length adjusting and bending the arm, such that the float travels the entire available depth, instead of just a portion of it.

did you happen to take pics while doing this repair?

 

[MIDNIGHT RIDER]

Sorry; no pictures.

This project was accomplished some years ago and, thus far, the float-arms have remained as intended.

 

[hesutton]

If, and that is a big IF, the sending-unit is electronically accurate, meaning there are no typical Ford dead-spots along the sweep of the gauge-arm, then it is a simple matter to re-form the float-arms such that the gauge reads dead-on accurate.

I retrofitted the generic J.C.Whitney sending-units into my tanks and bent and adjusted the float-arms until my gauge shows the real story.

The $16 J.C.Whitney sending-unit is light-years ahead of the costly Ford unit, far more durable and way more accurate.

Before, both of my tanks would read way past FULL for a hundred or more miles, then steadily drop toward EMPTY for another fifty miles, and fall way below EMPTY before ever sucking dry.

Now, exactly on "F" is neck-full and "E" is bone-dry.

All it takes are a few measurements; over-all depth of the tank at the sending-unit location and at what exact point of over-all depth measurement the pivot-point of the float-arm resides.

The rest is just length adjusting and bending the arm, such that the float travels the entire available depth, instead of just a portion of it.

Damon, do you happen to know the part number? What about the harness plug? Was it a direct fit or did the plug need to be removed and redone/remade?

Heath

 

[dgr]

Damon, do you happen to know the part number? What about the harness plug? Was it a direct fit or did the plug need to be removed and redone/remade?

Heath

X2

 

[MIDNIGHT RIDER]

I did have links to all of this saved in my "favorites"; alas, all that somehow got lost.

A member here and also on Ford Truck Enthusiasts site, FELLRO86, did a very instructive pictorial write-up (on Ford Truck Enthusiasts whatever site) that shows every detail of retrofitting a generic J.C.Whitney sending-unit onto the fuel-tubes of our trucks.

This has been beat to death over the years and there should be numerous threads, both here and at that other site, describing the whole process.

It is not plug-and-play; but, by following FELLRO86's instructions, it is easily doable.

Be fore-warned that there are several different "ohms-resistance" sending-units available from J.C.Whitney and be sure to get whichever one is specified for our trucks.

If memory serves, the 1980-86 takes an entirely different animal than the next generation, then maybe the later trucks after that generation went back to the same as 1980-86.

It has been a long time, but as best I remember, there is no wiring "plug" on the J.C.W. units, but a single stud for attaching the wire.


ON EDIT: >>> Now that I think about it, seeing as how the J.C.Whitney unit gets piggy-backed onto the existing Ford fuel-tubes, BELOW and INSIDE the bulk-head, as best I remember, the gauge wiring was simply spliced onto the existing Ford wire INSIDE THE TANK, thus leaving the O.E.M. wiring plug un-altered.

I wouldn't trade my cheap generic J.C.Whitney units for brand-shiny-new O.E.M. Ford junk and $200 to boot, that is how much better they are.

 

[bagpiperjosh]

I would imagine that if my showerhead thingy is all busted up, that its not available anymore? thus why everyone has to fab something up?

 

[hesutton]

Man I can tell you I searched and searched for Mr. fellro86's article on FTE and I have now given up after nearly two and a half hours. Oh well.

Heath

 

[bagpiperjosh]

Man I can tell you I searched and searched for Mr. fellro86's article on FTE and I have now given up after nearly two and a half hours. Oh well.

Heath

Yea, i had no luck finding it either

 

[dgr]

Midnight,
Can you look at this item and tell us if it rings a bell on what the JC whitney unit looked like when you installed it?
http://www.ebay.com/itm/Datcon-Fuel...nit-240-33-ohms-6-24-adjustable-/260946681590

Heath,
I have some news. I can't tell if it's good or bad. Here is the "article."
http://www.ford-trucks.com/user_gallery/displayalbum.php?&userid=170072&albumid=16937
I remember looking for the JC Whitney "universal" ones and came up empty. However, today after retracing my steps, I stumbled on these.
http://www.jcwhitney.com/adjustable-fuel-level-float/p2005714.jcwx
Nice thing about datcon is they are sold in marine stores so the chance it working for a diesel is more likely
Here is a datcon catalog. Interesting stuff on page 48.
http://www.partdeal.com/media/wysiwyg/Datcon-Catalog.pdf

These guys claim to have them for an 86 but I don't know if they do or if they would work in a diesel.
http://www.jcwhitney.com/gas-tank-sending-units-without-fuel-pump/p2005708.jcwx?filterid=c2072

If someone has a broken front tank sending unit for a bull nose, I sure would like to try and fix mine with a universal one. I don't feel like having a big hole in the top of my tank though.