When filling up the gas tank, the gas gauge only reads 1/4 tank. The idiot light turns on when the gauge get to just under 1/4 tank. Would this be a bad sending unit or gauge. If itis the gauge, is the gas gauge seperate from the other gauges or is all the gauges 1 piece?
to make sure I understand you: The idiot light comes on when the tank is 1/4 full (normal), but, your tank always reads 1/4 full, so, the idiot light is also always on for you? I haven't dealt with this before, I'm curious also. I'm thinking it through. At the end of the line, the first sensor is just a buoy that floats on the gas level, sitting right where the pump pickup is: so it's normal for it to read different levels when you're going uphill or downhill. Now, that's probably attached to a variable resistor, so that as the buoy goes through different angles the return voltage reflects that. There'd be two ways a car manufacturer could go from there. Send it to a computer and then have a little actuator to move the gauge needle, but a simpler possibility is to have a solenoid generate a magnetic field to resist a spring. That is roughly how your speedometer works, for example! I suspect as a car ages it will read higher and higher speeds than is actually the case: but, my '90 colony park still has an accurate speedometer. The idiot light does not get its info from the mechanical gauge, it could simply read the voltage directly and come on when the voltage falls beneath the level that it was programmed to come on at, to reflect 3/4 empty SO if the gauge is stuck at 1/4 tank, BUT the idiot light is not always on --only comes on when the tank actually reaches 1/4 tank-- it is probably the gauge itself. If the idiot light is always on, I'll ask a friend who's a ford tech and knows these cars still where to go from there. Don't just start swapping parts. Ford won't stock the gauges anymore, and if they did, you won't want to know the price. Rockauto might? But seriously, your best option will be a u-pick/u-pull junkyard, and just take the whole dash inset with all the gauges home with you
It's a good possibility that the float is stuck in the tank. Although, not being a Ford guy, I'm not real familiar with the pump/sending unit on that wagon.
BerniniCacO3, You are just a fountain of knowledge. To elaborate the issue, if 1/4 was a full tank, the the gauge would appear to function correctly. Assuming the gas gauge read correctly, the idiot light would appear to work correctly. When I purchased the vehicle, the seller and myself thought the gas tank was near empty. to fill it up, was only 8 gallons. The vehicle then made the 100 mile trip to Big Spring, TX from Seminole, TX. Getting into Big Spring, the gas gauge read near empty again. The car has been driven 5-10 miles since that trip (looking to get it completely fixed and registered before doing any real driving in it). A friend of mine (that is familiar with cars, also happens to be Canadian, but I don't hold that against him), thinks the gas tank collapsed in on itself due to vacuum - making the 20+ gal tank a 9ish gal tank and causing the float to always show the wrong gas level.
Your friend is an idiot: gas tanks are rigid and don't just collapse! I suppose one could try to back over a boulder and crush it, but you'd have other issues... like pouring gas from the burst seams I think our gas tanks are metal, and they can star leaking at welded seams, and they can rust through: those are about the only issues the tank itself can have. If it's a plastic tank, it can crack. None of these scenarios are all that frequent mind you. whoops, not a spring and solenoid for a magnet, but a bimetallic spring (expands and curls when it heats up), which expands with respect to voltage: http://auto.howstuffworks.com/fuel-gauge1.htm Idiot light is still working at all times in conjunction with the gauge then? I'd say your gauge is probably good. Something just occurred to me! A low voltage will fail to heat up the bimetallic strip, and likewise as read by the idiot light, will always show up as low fuel. So you're left with two possibilities now. One is that the float itself is stuck, and the other is a wiring issue: an open or a short to ground that causes no voltage at all, or full voltage but no real amperage, to reach the gauge. One last question. My fuel gauge on my '90, the needle swings all the way to the right and vanishes when it's full. Then the idiot light comes on at 1/4 tank, and if I keep driving another 50 miles, the needle creeps just under the 1/4 mark when I've only got a gallon left (I'm guessing: because I was able to put 16.7 gallons in at that point). Not perfectly accurate. If your gauge is stuck just under the 1/4 mark, maybe it's perpetually reading completely empty, not 1/4 full? The needle NEVER moves? Not that that really helps. A wiring short, a wiring open, and a float sunk to the bottom of the tank will all give you exactly that. Where from here? I'll ask my ford friend tomorrow if he has ideas. I'm not that good at tracing wiring faults yet, and I don't want to tell you to rip apart the dash when it turns out there was a convenient harness right under a piece of trim that you could have backprobed. If it's a wiring issue, you have 40 feet of wiring that goes from the battery to the float and back to the dash, most of it hidden, and you want an efficient method to find the fault without tearing apart the car. Or if it turns out these cars have a history of stuck fuel floats and that should be the first place to look.
The gauge does move! When the tank is full, it reads 1/4 - no idiot light. Use about a gallon of gas, the needle drops to just under 1/4 the idiot light comes on. When the needle is on E, approx 9 gals fills the tank.
Ah, OK. I wasn't clear on that point. It should be an 18 gallon tank, btw. I hit the trip meter, in winter I can go 250 miles quite safely, in summer 300, if you don't get this fixed right away. Wiring harness can build up corrosion, becoming resistive without actually cutting the circuit. This could lead to a low voltage reaching the gauge, and would register as perpetually low on gas. I'm not sure how the idiot light works: if it operates directly on voltage, then you've got a wiring problem before the gauge. If instead, the needle mechanically connects a circuit, then it doesn't necessarily have to be wiring. It might be something wrong with the couple moving parts in the gauge itself, after all. Let me ask my ford employee buddy Jim tomorrow, now that I'm quite clear on symptoms. Working on the tailgate this afternoon?
This is the only real issue that bothers me about the car. It took the 100 mile trip when first purchased like a dream. Fuel Economy wasnt bad. Approx 40 Miles @ 80-85 MPH took 2.3 gal (17MPG for those that are math impaired). I just got a bunch of sound deadening material for the Mustang. I was looking to start tearing it apart to prep for that.. Both the Mustang and Colony Park will have full systems (comp quality systems from previous cars we used to own).. Ill grab some pics and spray down the tailgate at the same time (thanx for reminding me)..
It's quite rare, but it is indeed possible for a gas tank to collapse. Best bet is to just drop the tank once it is low (which shouldn't take long on these cars unfortunately) and have a look to see how the tank looks and if that is fine pull the sending unit and float.
Don't be calling people idiots so fast or you can make yourself look like one. I've seen many steel gas tanks collapsed like beer cans from putting a non- vented cap on a tank that is supposed to have one. Here's one for example. Thy stay crushed or pop back when you take the gas cap off and when they suck in air the fuel shoots out right into your face if you don't know not to stand there and look at it. If you took high school physics or pumped gas in the 70's you'd know all about it.
hahah! Even as I typed it, I figured it could blow back in my face. But I couldn't for the life of me imagine a tank being crushed by mere vacuum, nor had I EVER heard of it happening before! Learn something new every day. Granted, I was born in the '80s. I've never seen a lubed suspension joint, I've never worked on a carburetor, and my own car is probably the last car with a distributor I'll ever touch.
OK, talked to my ford friend, and while he confirmed that high-impedance wiring is possible... that far more likely the floats themselves simply become saturated with fuel and sink, and that he's seen it many times on these cars in his career. Rock auto does not have them, but autozone has the float listed as "fuel gauge sender" or "fuel gauge sending unit" and it's not so rare nor expensive as I feared! I'm sure others have it too. Amazon ships free, here's the auto meter (generally considered a little better than their competitor sunpro): http://www.amazon.com/Auto-Meter-32..._1?ie=UTF8&s=automotive&qid=1302312596&sr=8-1 Let me know how hard it ends up being to change out! Can it slip in through the back of the fuel tank, or do you need to empty and then drop the tank? I might do mine preemptively one of these days. I like keeping my own colony park in perfect working order.
