To V8s Only - How bad does your mileage suffer with short trips?

[section525]

What are you 2WD guys getting on the highway?

100% stock I'd get 17-18 going up the I-5 at 75-85 mph.

 

[spta97]

100% stock I'd get 17-18 going up the I-5 at 75-85 mph.

Is it only the 2WD people who are getting this kind of mileage on the highway? Yesterday I went about 100 miles on the first 1/2 tank doing mostly highway driving not great, but better than the last tank. I calculated the mileage on the previous tank at it was 6.7 MPG!!!! Ouch!

On the bright side my new thermostat heats the X up MUCH quicker so I won't be burning as much gas in the morning.

 

[Claus]

You'll find my milage detail at:
http://www.niesens.com/hobbies/cars/2003-ford-explorer/Gas Log - 2003 Ford Explorer.htm

I did noticed that local/town driving has the worst fuel economy while the difference in interstate travel with or without a trailer in tow is less significant.

Basically we are using the Explorer on long distance for towing the boat and otherwise I use it to drive to work every day (~3miles) since we really don't want a 3rd car. For the other long distance travel we use the Jetta TDI with has milage that shouldn't be compared to the Explorer.

 

[Mbrooks420]

Check the fuel rail pressure. Your regulator is probably bad. At 7 mpg I'd say something has to be wrong. Running super rich is bad for the top end, and will beat up your rings, cylinder walls, and ruin your cats.

 

[spta97]

Check the fuel rail pressure. Your regulator is probably bad. At 7 mpg I'd say something has to be wrong. Running super rich is bad for the top end, and will beat up your rings, cylinder walls, and ruin your cats.

How would I go about doing this? The dealer can't find anything wrong but I wonder if a good mechanic would?

 

[aldive]

Put a fuel pressure gauger on the Schroeder fitting and test the pressure.

 

[spta97]

How much does one cost? I'll check my Haynes manual tonight to see if they have instructions there.

 

[aldive]

How much does one cost? I'll check my Haynes manual tonight to see if they have instructions there.

You can purchase one for less than $50 at an auto parts store. Its a handy tool to own.

 

[spta97]

You can purchase one for less than $50 at an auto parts store. Its a handy tool to own.

That might have to be a rental tool. I don't forsee owning an American car ever again so I hope to avoid these problems or have a warantee that will cover them.

Where is the valve?

 

[IAmTodd]

That might have to be a rental tool. I don't forsee owning an American car ever again so I hope to avoid these problems or have a warantee that will cover them.

Where is the valve?

If you look directly under you upper intake on the drivers side, look straight at the vehicle, it sits back in a little bit and looks similar to a valve stem on a wheel.

 

[jayhawkexplorer]

That might have to be a rental tool. I don't forsee owning an American car ever again so I hope to avoid these problems or have a warantee that will cover them.

Where is the valve?

American cars aren't the only ones that have issues. If you think its expensive buying parts for it, wait until you need something for a foreign car. If you really want a warranty, you'll be buying a Hyundai, Mitsubishi, or Kia; the other foreign car companies have the same 3 year/36,000 mile warranty the 2 US and one US/German company have.

 

[spta97]

American cars aren't the only ones that have issues. If you think its expensive buying parts for it, wait until you need something for a foreign car. If you really want a warranty, you'll be buying a Hyundai, Mitsubishi, or Kia; the other foreign car companies have the same 3 year/36,000 mile warranty the 2 US and one US/German company have.

Not to bash American cars but I've had much better luck with Japanese. Of course my next car will probably be a BMW so I'm sure I'll be in for a head ache then

 

[spta97]

I setup an appointment with a mechanic to take a look at my X. They should have more equipment than I do to diagnose the problem and hopefully be able to find out why I can't get the mileage that other X's that have more miles than I do. I'll post back results.

 

[spta97]

Well I brought the X to the mechanic today. When I called him in the afternoon he said that most of the systems checked out fine. However he did note that the fuel pressure was up at about 55 PSI at idle and it should be at 35 PSI. His first instinct was to change the fuel pressure regulator but he later said that it does not have one in the truck. He needed more time with the vehicle so I'm going to setup another appointment.

When I asked him how much I owe him he said nothing because he hasn't found anything yet. Far cry from the dealer with their "Diagnostic Fees". I'll post back when I have more info but it looks like they are onto something. It's also nice to have a mechanic who tries much harder than the dealer and doesn't rip me off!

 

[Jester1994]

Definately keep us updated. Do you know how he checked the fuel pressure, I am curious as to what mine would read. Keep up informed of your findings!

 

[spta97]

Not sure what tools he used, but I will keep you posted with my progress. I think I'll setup an appointment for the week after next.

 

[V8BoatBuilder]

Definately keep us updated. Do you know how he checked the fuel pressure, I am curious as to what mine would read. Keep up informed of your findings!

Checking FP is very easy:
1) Buy a gauge from Autozone for $35
2) Look ontop of the engine, behind the coil packs, on the pass side of the air intake. On the fuel rail there is a black cap covering a schreader valve.
3) Insert the gauge connection onto the schreader valve, start the engine up, and voila, fuel rail pressure.

Also - pre 1999 trucks with the return style fuel system DO have vacuum-based FP regulators. 1999s, such as spta's have an electronic regulator at the fuel pump.

 

[spta97]

Checking FP is very easy:
1) Buy a gauge from Autozone for $35
2) Look ontop of the engine, behind the coil packs, on the pass side of the air intake. On the fuel rail there is a black cap covering a schreader valve.
3) Insert the gauge connection onto the schreader valve, start the engine up, and voila, fuel rail pressure.

Also - pre 1999 trucks with the return style fuel system DO have FP regulators.

Do you know what regulates the pressure on post 99 trucks?

 

[V8BoatBuilder]

Do you know what regulates the pressure on post 99 trucks?

It's electronic, at the fuel pump. As a 1997 guy, that's about all I know. Sorry.

 

[spta97]

It's electronic, at the fuel pump. As a 1997 guy, that's about all I know. Sorry.

I wonder if there is something wrong with the fuel pump? This makes me wonder, if the pressure were to be taken down 20 PSI what type of effect would that have on the performance? I would hate to loose power as a result of fixing the gas mileage issue.