Hey guys & gals,Im having gauge issues so Im here to find out where I should start trouble shooting.The trucks got over 200,000 miles on it so there are a bunch of parts that could be gone out with this kind of mileage.
1) The fuel gauge needle is stuck right below the empty mark & never moves.This started about 3 months ago.
2) The battery gauge stays in the normal range until you turn the headlights or ac on.The ac will cause the needle to drop alot,even if youre moving at cruise or highway speeds.
3) The temp gauge reads a little between the O & R when idling,accelerating or cruising,but if you turn the ac on & stop in traffic,the temp gauge needle will start climbing above the M & A mark.If you manually spin the cooling fan (cold engine)it has resistance.It will spin 1-2" before coming to a stop.It seems to have the same amount of resistance on a hot engine too.
4) The oil pressure gauge reads slightly above normal,but will drop slightly if the engine is idling.I had read that these oil pressure gauges will read in the normal range if pressure is anywhere above 6psi & will read zero if pressure drops below 6psi.

Im gonna remove the upper intake this weekend to replace the back two spark plugs on the driver side.I know it can be done without removing the intake,but Im also gonna clean the tb & intake ports,clean the egr valve & pipe then remove & soak the oil separater in gas.This will give me easier access to check the secondary ground on the back of the head.The ground is tight at the firewall & it feels tight trying to move it by hand(at the head) but I cant get to it with a wrench to see just how tight it is.
I bought a new temp gauge sender Im gonna replace while the intake is off.Do the gauge issues sound like a loose/corroded ground,individual gauge problem (i.e.-bad sender,open/shorted wire)or maybe a instrument cluster voltage regulator on its way out??
Any suggestions??

 

Only the fuel one looks like a "gauge issue", but it is most likely the sender/float in the tank.

First thing you need to do is get a Volt/OHM Meter, and hook it up to the battery.

Good battery will show 12.3v to 12.9v key off
12.2v and under means battery is not recharging or is more than 5 years old

Start engine, battery voltage should now be above 14v, up to 14.9 is OK, not above 15v
This is "Recharge voltage" it means the voltage regulator has detected drained battery(from starter motor) and is recharging it.

After a few minutes voltage will start to drop, it should go down to 13.5v and stay there.
This is "Maintenance charge" it maintains the battery's 12.3-12.9 voltage, it is usually 1.1v above battery voltage, so battery with 12.5v, key off,would show 13.6v after recharge, engine running
If it stays above 13.9v for too long then battery fluid will start to evaporate shorting battery life

Now turn on head lights and heater fan Blower to High
Voltage should drop and come ring back up to 13.5v, if not then voltage regulator OR 1 or 2 Fields are not working.

An Alternator has 3 Fields, each generates voltage, it is not uncommon for one field to fail as alternator ages , often noticed as dimming headlights at idle, NO.....that is NOT normal, lol, 1 field is bad, but since you are driving more than idling it can last that way for years.

So check the charging system, Volt gauge AND oil gauge are both changed by system wide voltage.
If voltage is dropping at idle, then oil pressure gauge would as well since it is powered by system voltage, and obviously Voltage gauge would too.
Fuel gauge has its own power supply, 5 volts so isn't effected by lower voltage at idle.



Yes, you have the classic symptom of bad fan clutch
rising temp at idle
And it reads like your test confirmed it


You need an OHM meter to test fuel level sender in the gas tank
You will see a Yellow and an Orange wire coming out of the fuel tank
(Pink and Black are for fuel pump)

Yellow wire will have 5 volts with key on, it will pulse up and down that is normal, if no voltage then power supply behind dash could be bad.

Orange wire is the Ground.

There should be a connector for these 4 wires follow them and look for it
When yellow and orange wire are disconnected turn on the key and fuel gauge should go all the way up past Full, this means Gauge is OK, problem is in sender.
If gauge stays below Empty then problem is in the dash.

The float in the tank can get a hole and sink to the bottom and stay there.
Or the sender is shorted inside so will read 0 OHMs if you test it with OHM meter.
test yellow and orange wires going into the tank, should read 10 ohms if tank is empty and 158 ohms if tank is full, if you get 0 ohms then there is a short which shows below empty on gauge.

Also Google: Ford anti-slosh module
This can also short out, it is behind the dash
If you want to pull out the instrument cluster you can test sending unit from there as well, yellow wire is on the back of the gauge cluster

 

Great trouble shooting info Ron,I'll get busy this weekend going over the things youve listed.My battery is only 6 months old & I had it & the alternater tested a month ago at AZ.The battery terminals are new too.I'll still test the battery with my multimeter though,like you mentioned.
I was searching google for fan clutch testing how to's and one site stated you could use a screwdriver to pop the end of the coiled spring out of the slot that holds it in place then turn it 90° and this would cause the clutch to be engaged at all times.The design of my fan clutch allows the end of the spring to be popped free of that slot,but if you let the spring rotate 90°,theres not another slot available to hold the end of the spring in place.You can see,in the picture below,how the tab at the springs end fits into a slot thats cutout,which prevents the spring from moving.If you pop it loose from that slot,another slot isnt available to hold it in place,if the spring is rotated.I was gonna try this to see if the engine still overheats with the ac on at a stop,but I dont see how its possible with the springs design. Any thoughts??
I'll check back after I do some testing over the weekend. Thanks for the help.

 

Never tried that so can't say.

The spring is heated by the radiator not the engine.
As the radiator gets hot the spring gets hot and when heated metal expands, so spring uncoils a bit and closes a valve inside the clutch
So if you were to unlock the spring it would have the same effect as expanding it because it would rotate in the same direction as expansion would, it would uncoil.

BUT(big but) you are assuming the spring is the problem, which it could be, but may not be as well.

And while it looks like a spring because of the shape it does not have much pressure load, it is in that spring shape to absorb heat and expand enough for the temp properties of the system it was designed for.

You can test your spring theory, can't hurt if it is already not working as it should, but I would budget for a new fan clutch just in case
Whether it would stay there is something I can't answer

PDF here for what you are thinking about: http://www.lbfun.com/warehouse/tech_...tch_adjust.pdf

You can dremel a new slot in housing if there isn't one, and this PDF is for changing the temp activation on a WORKING fan clutch, not to fix one that isn't working.


EDIT:
One other thing to check is the main Cab ground strap.
Battery is grounded to the engine, because starter motor and alternator are the biggest amp users.
There will be a ground strap from the engine to the Firewall, main ground for the cab electrics.
Usually from the back of the head to the firewall, drivers side head if a V6
This can get loose or even left off after engine work.
Cab is bolted to the frame and fenders BUT........these are pre-painted surfaces when bolted together and sit on rubber "washers" so not really good grounds
And engine and trans sit on rubber mounts as well so no good electrical connection to the frame/body
Check for the strap and make sure it is clean and tight

 

General rule of thumb on overheating: If it overheats in stop and go, it is the fan, and if while highway driving, it's the radiator.
IF you have a problem. You should expect the temperature to rise a bit when idling in traffic with the A/C on. More heat added to the air passing over the radiator, so it has less temperature differential between the radiator(coolant) and ambient air, will cause the temperature to rise given a static or constant airflow over the radiator.
The question is how far the needle will go in traffic across the "C normal H" range. Most gauges have a 'bar' with bookends, and any reading in that range is OK, but don't go past the end of the range. Get a non-contact thermometer and read on the upper hose right outside the thermostat housing.
The test for a clutched fan is whether it will 'zoom' when idling. Many are worn out, and will no longer do that. The 'zoom' is when the temperature has been high enough for long enough to unwind the spring, and close the internal valve. Then the clutch will 'lock' up, the fan speed increase a LOT, and the air will start to 'zoom' past the radiator. Zoom may be the wrong word, but you should be able to tell, from what I've read.
I need a new fan as the blades are brittle and starting to lose chunks, and the clutch just doesn't work that well. I don't have overheating, but it is not like it was.
Finding information about fans is like searching for snipes. What will fit, spacers, etc are all 'mystical'. Ford OEM is NLA for my truck. What to do...
tom

 

Sorry about the delayed response.I had to do a hydraulic clutch conversion on a friend of mines 92 Mustang this weekend,so I didnt get anything accomplished on the Ranger.

I checked the secondary ground,youre referring to,at the firewall end,but Im gonna wait a couple days til I remove the upper intake,to check the cylinder head end.Im removing those parts to clean the tb/ intake ports/egr valve/egr tube & iac valve plus Ive gotta drop in the last two spark plugs(will be easier to access with these parts removed)to finish my tune-up.

Ive also got a new temp sender to drop in,since its easier to get to with those parts removed.Do you suggest removing and soaking the oil seperater in gas or some other solvent,while Ive got easy access to it also??

I might try that little trick you mentioned about cutting another slot into the fan clutch, just to see how well this works as a trouble shooting method,but I'll check that pdf out you listed.

Im gonna take a few pics tomorrow of all of the gauges,with a cold running then warm running engine, idling-ac on & cruising-ac on so you can get the full scope & see if anything else stands out that you haven't mentioned yet

I find it odd that the battery gauge reads as low as it does,when the ac/heat is running & the fan is on any setting from low to high,considering the gauge doesnt even go up when youre doing 75 on the interstate or when revving the engine up.Seems like it should increase.The battery voltage tests pass koeo & koer,but yet the gauge doesnt register the same.
Oh well,I'll get those pictures up tomorrow hopefully so my gauge explanation is a little clearer.
Thanks Ron,WBRock

 

Well I managed to snap a few pics today,so I'll post them below.
I noticed with the truck idling at operating temp,with the ac turned on,the fan was spinning quite fast.However I wrapped a towel around my hand & grabbed ahold of the fan & it stopped instantly with zero effort.

I drove the truck for 30 minutes,to get some pics,then drove it back home.While it was idling,I turned the ac on & after about 2-3 minutes the compressor started to make noise.It wasnt a whining or bearing roar type noise,but more like a rattling noise.When you push the fan button in to activate the ac,it really pulls the battery down,on the gauge & you can feel the drag on the engine quite a bit too when youre cruising.
Well maybe these pics will show something.
BTW-sorry about the dusty pics.Went down a dirt road before getting on the highway.lol


1st pic=cold start/idle/ac off
2nd pic=oper temp/cruising/ac off
3rd pic=oper temp/cruising/ac on
4th pic=oper temp/idle/ac on
The 4th picture was after I came to a stop,sitting there for 3-4 minutes. Gauge was continuing to climb when I shut the truck off.

 

Fan clutch is bad, period

Alternator could have lost a field, with engine warmed up and idling, AC off, check battery voltage, should be 13.5volts
Turn on head lights and heater fan to HIGH, voltage should drop and then come back up to 13.5v
If its down to 13v or under then you need a new alternator, you have a bad field.

 

Ok and get around to testing that today.Thanks for the help