Alright guys, tonight the 5.0 transplant finally went down the street, and after a few minor adjustments it shifted fine through the gears.
Now on the way back the full gague will all of a sudden went all the way to full. Since last week when the car took its first breath in the new car the gas gague has been teetering half way. Now all of a sudden it went to full. Now I am thinking its a ground, it worked fine earlier and I'm hoping its not the sending unit in the tank. Any suggestions?
Anyone? I've checked the ground on the back side of the dash(the drivers side) and it seems fine. The gauge automatically goes to full. I'm thinking this is a ground problem somewhere...As usually they go to "E" is the sending unit is bad, right?
By the way when I turn the key off it goes to "E" like normal, but when the key is on, it immediately speeds its way to past full. Its not instant but definately faster than normal.
Anyone had a similar problem?
Sometimes the voltage regulator on the back of the cluster can cause the guages to top out their readings. Though if it's an buttstuffog cluster all the gauges will read high. Which gauge cluster do you have?
My buttstuffog will act up occassionally. If I tap on the cluster it will begin to work correctly.
Not exactly a technical solution, but if you tap on it and the gauge begins to read correctly, at least it will isolate it the cluster. If it has no effect, you will still have to test the wiring to the gauge...
Well i just got the temperature working, It reads in the middle of the gauge, so I'm assuming that is normal for a stock 5.0. Its the base cluster.
I've tried tapping on the dash to no avail. When the motor first ran the gas gauge was about halfway up, about where I think it should be.
I read through the CoolCats and it mentioned tapping on the gas gauge too in order to try and isolate that. Neither have caused the problem to change. What grounds should I be checking? Anything else?
Alright, well ive checked everything I can think of. It appears its either the gauge or the fuel sending unit. Where can I get a sending unit, everywhere I call seems to have a fuel pump and sender in one. My fuel pump is only about 6 months old, I just want a sending unit.
Check the sender to see how many ohms it's sending out. If it reads off the scale, it might be grounding it's self out.
It should only be about 8-12 ohms at full
and between 60-86 ohms empty.
These are buttstuffog readings
I've been doing some experiments with one in the last week
Are you doing this at the pins in the dash? where you getting the readings from?
You should get the reading off the 2 wires that come from the sender.
Not sure what color they are at the dash. I'd have to look them up.
Also does anyone know which fuel sending unit is discontinued. I read an earlier post and someone had a base cluster and couldn't find a sending unit. Can anyone confirm that the base sneding units have been discontinued or was it the full digital sending units?
Is there even a difference between the two of them? If so, what is it?
looks like a yellow/white and a black ground wire
The digital sends the ohms reading in reverse
full= empty
empty=full
From what I understand it was the digi sender that is a bear to find
also, most places list the pump as a sending unit.
I may have also found a way to turn 1 into the other. :D
can you explain? I have one from a digital cluster than seemed to work fine... Im assuming now they are different. Please help me... :)
Wait a minute.
If the sender came from a base digital cluster,with a regular gauge, then it will work the same.
If it came from a full digital cluster including digital gas gauge. Then it reads opposite.
I wasn't sure which one we were talking about.
he has a parts car with the full digi with a working good sensor...
The car which isn't his parts the one with the problem is a Base Cluster... which is a bad sensor... Also a different fuel sender then the full digital...
They make the full digital still but not the basic cluster, and the buttstuffog and basic cluster share the same unit...
He wants to know how can he use the full digital sensor with the base cluster... If u have a way of course...
I would check the readings to make sure it's not a wiring issue first.
check at the dash and right at the sender.
After checking the wiring and the gauge seem to be fine. I would think this would mean the sending unit it bad. I've talked to ford and i've loooked aftermarket, I seem to come up with nothing. Everything seems to be a eihter a joint fuel pump and sending unit, or they just don't know the difference between them.
I may still be able to get the full digital sending unit from Ford, the dealership that its allegedly at was closed by the time i got the infor about them.
Sounds like it's time to see if Vinnie has one.
Alright well I thought you had a way to convert one to the other. Seeing I already have the full digital sending unit out of my parts car...
How are you with electronics and soldering?
Well i soldered the jumper wire in my cluster, and a handful of wires on my engine harness to weatherproof them. As far as electronics I'm not sure what you mean, but with instructions I'm fully capable of learning and trying something new in order to reap the benefits of having a gas gauge again.
lay on your back under the tank
look to the right
find a two wire harness
one wire is yellow / white
the other is likely black.
this should be the sender harness
grab harness and follow its path up
it should be going up and finally under your package shelf in the trunk
package shelf-in trunk up near speakers (connector c491)
get in trunk
look for a connector with yellow white wire and a black
unhook connector
one end goes to your dash guage
the other goes to the sender
disconnect sender connector
connect red meter lead to the yellow white
connect black meter lead directly to the metal tank***
do not deviate from the above two steps or reading may be wrong
set meter to resistance and read
jot down that number you get
add 5gal of gas
read sender
jot down that number
if there is a change then the sender is assumed to be good.
To test the guage, insert a paper clip in the connector (C491)
turn on key
gas needle will peg if its good
gas needle will peg if its a conventional cluster
gas needle will go to empty if its a digital cluster sender
go to my diy link below for details.
you will find a link here to "guages" with wiring diagrams.
go to my electrical tech sticky "1987 evtm" page 129 for wiring diagram.
post your results
You can define what sender you have based on your readings as well as determin if it works.
I have often thought that if one puts a digital cluster sender in a conventional dash car, the leads on the guage can be flipped there to compensate for the tank circuit,,,,,,,,,,(you getting this daminc?)
If i get what your saying here,,,,,,,,,
you are saying you have installed a digital dash sender?
If this is the case then you must have a full tank of gas already,,,correct?
if so, everything is fine, your sender is just opposite.
I dont see how you had it working fine with a digi sender then all of a sudden things went wacky.
with a digi sender connected to a conventional cluster, things should have been opposite all the time.
if so,,,,,
disconnect C491 connector in the trunk near speakers
this is the yellow / white with black wire
jumper your yellow white wire to your black black wire
jumper your black to your yellow white
turn on key
see what happens
Jcassity, thanks for the info.
I have a normal sending unit installed in the car right now. But I have a full digital sender out of my parts car that I was curious to see if it worked.
Why bother? you need to verify what you got works first.
Where is connector c491? I'm looking in my EVTM for 1988 and can see it. But I'm unable to tell where it is in the car, its before the gauge, but im not sure where.
If you look ahead another page or two it will tell you where the connectors are located.
Jcassity
When you gave me instructions how to test the sending unit you told me to ground the meter to the metal tank. Why is that? I'm curious what the difference is if I ground it to the tank or anywhere else.
The grounding pin on the connector is the same as grounding it to the tank, but takes the grounding pin out of the trouble shooting. Any bare metal spot, or around the sending unit ring will work on the tank.
What parts have you tested so far?
I would start with the sender it's self, then the wiring, then the dash stuff.