Fuel sender issues | Ford Explorer - Ford Ranger Forums - Serious Explorations
  • Register Today It's free!

Fuel sender issues

adrock430

Member
Joined
October 26, 2009
Messages
23
Reaction score
0
City, State
Boston, MA
Year, Model & Trim Level
1994 Ranger XLT 4.0L
Hi all,
This is my second sender install on my 115K mi 94 XLT 4.0L. First change was due to rot, second change was due to error on the gas gauge, which I figured was do to me slightly bending the sender when installing.

Installed the new one, no bend, and I'm still getting a reading that is higher than what it actually is. Once I get to half way thru the last quarter reading on the gauge it stops, leaving me to guess where the fuel level is by tach.

Is this a faulty gauge then? Is there a way to advance the needle to reflect an accurate fill level?
Thanks, Adam
 



Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!
.





Roadrunner777

Explorer Addict
Joined
February 5, 2011
Messages
2,044
Reaction score
338
City, State
Bemidji, MN
Year, Model & Trim Level
94 4x4 Sport 88k
I had the same issue on an Airtex assembly I installed about a month ago. It worked itself out after a few tank fills, letting the fuel level get as close to empty as I dared. (I carried a 1 gallon gas can, for what it's worth, never had to use it.)

If you are the analytical type, you can figure out what is going on my measuring the sensor output. Open the fuel pump electrical connector and figure out which end goes to the fuel pump assembly. Measure the resistance across yellow/white and black yellow. The spec is 145 ohms at full, 22.4 ohms at empty. Drive until the gauge appears stuck and measure/record the resistance. Then drive a significant distance (say, 50 miles) and measure it again. The result will tell you if it is the pump assembly or the gauge. It's going to be the pump assembly though, because the issue started when you changed the pump assembly.

For the final say, you could pull the pump assembly and bench-check the resistance.

Personally, I'd wait it out and see if it clears up like mine did, particularly if it is an airtex. Maybe a bad lot made it out the door... airtex is not the best brand out there. And, I'd be a bit concerned that, if you swap it out, the new one will also be defective. Was it an Airtex purchased from O'reilly's? Mine was.

Keep us posted!

Phil

BTW, I don't think it is the case here, but there is a small circuit board in the instrument cluster called an anti-slosh module. A failure here would be indicated if the fuel pump assembly were sending correct resistance values.

BTW #2 , after a few minutes thought, you could have some corrosion at the fuel pump electrical plug. If a corroded contact added 20 or 30 ohms, that could do it too.
 






larrydd999

Elite Explorer
Joined
December 14, 2010
Messages
443
Reaction score
15
City, State
Port Angeles, WA
Year, Model & Trim Level
92 XLT, 94 Limited
I haven't changed a fuel sender unit yet on either 'ex' (I wimped out and had a local shop do it), but is it possible that the sender arm is hanging up on something in the tank - like maybe the side? I did have to change the senders on my boat and had to be very careful to orient them properly.

Larry, KC7JJ
 






Roadrunner777

Explorer Addict
Joined
February 5, 2011
Messages
2,044
Reaction score
338
City, State
Bemidji, MN
Year, Model & Trim Level
94 4x4 Sport 88k
A point of clarification, just so we are on the same page... The sender (just a variable resistor with a float) is an integral part of the fuel pump assembly. You can buy just a pump and replace it, using the old assembly with the old sender, but I'm going to assume you are replacing the entire assembly with the pump.

I replace this assembly with the tank in place, through a hatch I cut under the passenger seat. A shop would probably drop the tank. But, going through a hatch, the lines have very little play and pretty well dictate the correct rotation of the assembly in the tank opening. Not sure about how this works out if you drop the tank.

At any rate, it would surprise me if an accidental rotation of 15 degrees either direction would make any difference. More than that, maybe so, particularly counter-clockwise because the float hangs out to that side. I'm pretty sure there is no key to insure rotation, but I could be wrong, mine just naturally fell in correctly.
 






adrock430

Member
Joined
October 26, 2009
Messages
23
Reaction score
0
City, State
Boston, MA
Year, Model & Trim Level
1994 Ranger XLT 4.0L
Thanks for the responses! I replaced the entire assembly, and yes, it was an Airtex.

Thing is, I replaced it before due to rot, and had a similar issue. I bent the shaft a bit trying to get it in that time, and figured that was the issue, so replaced it again. Gauge get stuck in the same spot.

What is the orientation, using the pins on top of the sender, to the tank? Right now, looking at the tank from the filler, they are at the 5 o'clock position (if I remember right).
 






adrock430

Member
Joined
October 26, 2009
Messages
23
Reaction score
0
City, State
Boston, MA
Year, Model & Trim Level
1994 Ranger XLT 4.0L
BTW, Bemidji?! I'm watching Fargo, the series on FX, now...its awesome!
 






Roadrunner777

Explorer Addict
Joined
February 5, 2011
Messages
2,044
Reaction score
338
City, State
Bemidji, MN
Year, Model & Trim Level
94 4x4 Sport 88k
tank3.jpg


tank11.jpg


The pins run inline with the car, towards the centerline... These pictures were originally on this site, but the user deleted them from photobucket. Google cached them though (Google caches everything forever, remember that!) I would credit the pictures if I knew who's they were, and will do so if they speak up. This shows the location to cut a hatch, which makes fuel pump replacement maybe a one hour job if you stop for beverages.

Yeah, final episode... the town is a little bit split on it, but I like it.
 






adrock430

Member
Joined
October 26, 2009
Messages
23
Reaction score
0
City, State
Boston, MA
Year, Model & Trim Level
1994 Ranger XLT 4.0L
Thanks for the follow-up, I was looking for those photos. My sender doesn't look like the one in your photo, but based on a youtube video of a guy changing one it's definitely in the right orientation.

Thing that makes this strange is that this is the same issue as the last sender. I'll try and bang around the tank to see if the arm is hung up somewhere, but I doubt it. Any other thoughts on the issue?
 






Roadrunner777

Explorer Addict
Joined
February 5, 2011
Messages
2,044
Reaction score
338
City, State
Bemidji, MN
Year, Model & Trim Level
94 4x4 Sport 88k
I did have the same issue with my new Airtex pump. It was sticking just above 1/4. I drove it past that a few times, hoping that, if it was hanging up on something, it would break loose. It did after about 3 or 4 rounds of that, and has worked fine since. I guess, if I were you, I would drive it past where it was sticking, getting as close to E as you can best safely estimate. Then, fill it up.

Actually, as I remembering more, there was one time when it was stuck, then suddenly dropped to 1/8 or so, and it has worked fine since.
 






larrydd999

Elite Explorer
Joined
December 14, 2010
Messages
443
Reaction score
15
City, State
Port Angeles, WA
Year, Model & Trim Level
92 XLT, 94 Limited
Adrock430, I'd like to go back to your first post where you say the reading is higher than actual. Does it show full when you have a half tank or something like that? It's possible that you have the wrong resistor - or a bad resistor - in the sender unit. There are at least 3 different values of fuel sender resistor ranges (as a former marine electrical and electronic service tech I ran into just about everything). The 'US' standard is 240-33 ohms, but the european/far east vehicles often use 3-180 ohms. If it's at all convenient to do so, I'd check the range of the sender with it out of the vehicle to verify it really does range between 240-33 ohms and you have the full range available.
 






natenkiki2004

Blue Bomb!
Joined
November 3, 2013
Messages
2,044
Reaction score
78
Location
North Idaho
Year, Model & Trim Level
1991 & 1994 Explorers
Just wanted to say, this is why I love this forum. Fascinating info from Larry, keep it up man :)
 






Roadrunner777

Explorer Addict
Joined
February 5, 2011
Messages
2,044
Reaction score
338
City, State
Bemidji, MN
Year, Model & Trim Level
94 4x4 Sport 88k
I have never found a graceful way to correct someone in a forum, please accept this with a smile and a handshake... The explorer apparently does not conform to standards. At full, the sender should read 145 ohms, and 22.4 ohms empty. Here is a screenshot from the factory wiring book:

94exp_fuel_gauge_sch.jpg


This is a link to a screenshot for the entire page, it is too wide to show directly in the forum:

http://www.explorerforum.com/photopost/data//500/medium/94exp_62-3.jpg

There are two good places to measure resistance. The schematic shows C311, which is the connector on the pigtail of the fuel pump assembly, which is reachable via the rear driver-side wheelwell. The other is C141, which is under the hood, on the driver's side on the wheelwell under the evap container. It has 7 or 8 wires and a blue plastic shell. C147 is the firewall connector, you don't want to go there, too many wires, too hard to disconnect. You should make these measurements with the connector disconnected to prevent influence from the rest of the wiring.

A few words about the anti-slosh module... it is a plug-in board, part of the gauge cluster. There is no wiring diagram for this board, but it contains an op-amp chip and a handful of other parts that ultimately provide a dampening effect so your gauge doesn't dance when you go over a bump.

Incidentally, these service manuals are widely available on auction sites. Dealerships are selling their old copies, so not too expensive. There are three books in the set (they are big, like phone book big). The wiring book is available as I write this for about $16. The others (one chassis, one drivetrain) are bigger and go for about $20 each. $50 seems like a lot for manuals, but remember what your time is worth too.

I'm sorry for the length of this post. Insomnia is a b!tch sometimes.

Best of luck!
 






adrock430

Member
Joined
October 26, 2009
Messages
23
Reaction score
0
City, State
Boston, MA
Year, Model & Trim Level
1994 Ranger XLT 4.0L
Thanks guys. The reading is accurate until 1/8 left. It just sticks then, same exact issue as the sender before.

The voltmeter is not my friend, but I'll break it out if need be. First I'll jostle around the tank to see if there isn't a hang up.
 












adrock430

Member
Joined
October 26, 2009
Messages
23
Reaction score
0
City, State
Boston, MA
Year, Model & Trim Level
1994 Ranger XLT 4.0L
Following up on this post, I've been thru a bunch of tanks of gas, letting get as close to E as possible, keeping a can of gas on me, etc...still no change.

Actually, now I'm getting big swings in the gauge, going from half full to 1/8 full when I have about a half tank. What do think may be causing this? Would it be the slosh module?
 






Top