Fuel tank problems

[KevinK]

How come my fuel tank on my 91 X will only take 10 or 11 gallons at a time? It's been like that for a while. I actually had it at the dealer and paid them $120 bucks to fix it. Pissed me off too much to even bother taking it back.

Any help?


Thanks,

Kevin

 

[410Fortune]

Maybe your gauge is off (it happens alot) and there is still a few gallons in there........

 

[KevinK]

It runs out of gas. It definitely only take about 10-11 gallons and that's it.

I thought it was the guage and tried to keep on trucking, wrong idea.

I guess I need to drop the tank and llok at the vent hose. Is the tank tough to drop?


Kevin

 

[410Fortune]

It's not as hard as you would think. Basically it is hung by a couple of straps, you just have to loosen some bolts, drop it down a little (using a jack) and unhook the fuel lines and elecrical. Now you need to be careful with a gas tank, obviously, no metal on metal contact, which means if you need to bang on the fuel pump use a wooden stick and a rubber mallet.

Cover the holes in the tank with duct tape to keep any debris out.

Took my buddy and I all of 1 hour to drop my tank, install a new pump, and re-install, it was a little less then 1/4 tank of gas and pretty heavy.

 

[Blake D]

Where is the fuel breather located at? Does it exit up by where you put the gas in or somewhere else?

 

[410Fortune]

The fuel breather is your filler tube and vented cap. THere are 3 tubes on the gas tank, the high pressure feed line, the low pressure return line, and the filler neck tube. Thats it, there is no vent tube on a gas tank, instead they use a venting cap....

You can test your cap to see if it still works. If you think there is pressure built up in your tank and thats why it wont take the 14 gallons its supossed to, look for your canister purge valve to be the cause, not the gas tank....

 

[Blake D]

cool so I don't need to relocate the breather tube for the gas tank when wanting to do water crossing unless I plan on going deeper than my filler tube?!!!!!
THANKS

 

[KevinK]

Excellent 410! So where is the canister purge valve???

 

[410Fortune]

the canister purge valve is located in your upper intake manifold just behind the throttle body, basically Ford found a good place to stick it and shoved it in there. Youcan pull it out to work on it.

Follow the fuel line hose from your charcoal canister up to where it goes under the upper intake (from drivers side) and you will find it. It is brass in color and is a little larger then a film canister. Napa has new ones for about $20.

The canister purge valve is controlled by the computer, the computer sends a - signal to the valve and it opens, allowing air to flow fromthe intake through the valve and basically purge all the gas fumes from the charcoal canister tothe fuel tank. The problem is when the canister purge goes bad (And they do alot, you will smell gas all the time under the hood) it sticks in the open position, so air is always purging the charcaol canister and sending fumes back to the tank, so as long as your engine is running you are forcing gas fumes and air into the gas tank, building pressure.

BE very careful replacing it! The plastic T fitting onthe new one breaks easy and the nylon fuel lines are a tight fit, you can take the whole thing inside (both lines, new canister purge valve) and boil the ends of the fuel lines in water to heat them up and make them easier to push on....

good luck! Also try searching for canister purge on these boards.......

 

[410Fortune]

OH FYI on a 91 the canister purge may be a lot closer to your charcoal canister, just kind floating in space behind the drivers side headlight. Look for a brass colored film canister shaped solenoid with two fuel lines going to it and two wires, one wire is grey with a yellow tracer, the other is grey/red or red, cant remember.

 

[KevinK]

Thanks 410fortune. I do have one more question, do you think that would be a reason for the tank to not fill completely? That is the part I'm having a hard time understanding.


Many thanks,

Kevin

 

[410Fortune]

I really doubt it.

I'm guessing you have a fuel pump problem and there really is still 3 gallons of gas in your tank when you run out, meaning your pickup tube has a hole in it or has come off. So basically it's like holding your straw an inch fromthe bottomof the cup, cant suck more fluid, but there is still more in there....

When you open your gas cap and the gauge reads almost empty does it sound like there is pressure in the tank?


The fuel pumps at gas station stop filling when they sense backpressure, so it could be pressure that stops the pump, but if you still try to pump in more gas and it starts overflowing at 11 gallons, there is still 3 gallons of fuel in there....


I would plan on dropping the tank and replacing the high pressure pump and float assembly, they are about $80-100, stay away from cheapo's from places like Autozone or checker, go for the Napa or carquest pump, you dont want to have to drop the tank again....

 

[410Fortune]

Hey have you visually inspected the tank? Maybe ythe tank has been dented? Just a thought.....


I believe a 91 Explorer has a 14 gallon tank....

 

[KevinK]

Yes, I have visually inspected the tank. No damage. But you may be on to something here regarding the tank problem. The tank is 19.3 USG. It will typically hold 10-11 gallons at any given fill. I have tried to keep filling the tank but it does overflows.

It does have pressure when I take the cap off. I guess I just need to drop the tank and inspect.

I appreciate all your good ideas and information.

Kevin

 

[410Fortune]

Replace the canister purge valve first before you drop it. Presusre in the tank = canister purge is bad. They seem to last about 80 K miles.

Also have your gas cap checked or replaced.

 

[KevinK]

I will do that first. It has 180k on it, so it's probably due.

I'll give you some feed back.


Thanks,


Kevin

 

[410Fortune]

180K!!!!!!!!! you need a bunch of stuff!! fuel filter, 02 sensors, cat convertor, water pump, belt tenshioner pully, and I would seriously consider looking closely at your nylon cooling fan, I bet you find lots of cracks and it';s about to fall off, if it does your looking at taking out the waterpump, radiator, belt, some hoses,and the hood.....

Teh replacement fans are about $30....

 

[KevinK]

I meant to say only 180k. I tried the fuel filter, it's stuck and stuck good. O2 sensor, well I never even considered or the cat conv., water pump..... Now the fan, I'll look at that tonight. I don't want to ruin anything. Especially since I replaced all hoses and radiator 2 years ago.

Any tips on the fuel filter? I used the special tool it just wouldn't budge. Will I need that special tool in oder to remove the fuel tank and fuel pump?

 

[410Fortune]

Yeah those pressure fittings are a real *****. Just make sure you are not pulling on the line when you shove the white tool in there, make sure the white tool goes in all the way and then pull apart, it's kinda like a chinese finger trap, you want to push the lines onto the filter, put the tool in all the way, then it will come apart no problem, no need to force it, if you get the tool in there it will come apart.

Now there is another tool that may help, instead of plastic it is made from aluminum and it has a handle built in so it really helps with the stubborn ones, you can pick this up at Pep Boys for $3

 

[KevinK]

Do you think it could be terribly corroded? That is what I suspected. I tried a little wd-40.

You got me thinking I'll just sell the thing. But I would like to get another one. Gosh, I just put Bilsteins on it 5k miles ago and wheel cylinders last weekend. Ball joints in the next couple weeks. This doesn't sound really good does it.