New fuel pump and MPG goes way down

Hello everyone. Ok here is the deal. My 93 Ford E-150 with a 300 six cylinder used to get close to 20 mpg on the highway. I am not sure what it got in town. Recently I had a new fuel pump put on. The repair shop told me that Ford stopped making the fuel pumps originally installed on my 93 Ford Van. My van has a 35 gallon fuel tank. They said something about a transition year.. hell, I don't remember the technical jargon. The only fuel pump available now is calibrated for a 27 gallon fuel tank. They said it wouldn't make a difference except for the accurancy of the fuel gauge. So in other words, the fuel gauge reads full until the tank drops down below 27 gallons. No biggie. But I noticed that my MPG plummeted. I get 10-11 MPG in town ( I haven't checked the highway MPG). Everyone I talk to says the different calibrated fuel pump wouldn't make a difference in gas mileage. But I am not convinced. I'm not a freaking mechnic. And I live in an apartment complex that doesn't allow auto repair. But I'm considering dropping the tank myself, and installing an original equipment fuel pump (from a salvage yard, perhaps) to test the mileage. Is it possible that a wrong fuel pump can cause a decrease in MPG. The engine runs perfect. I recently got new plugs, new filters. What else can it be? I am so frustrated over this. I look forward to your thoughts and opinions. Mezzo

Reply to
mezzodock
Loading thread data ...

This is the second time I've seen this post.

How are you measuring your mileage?

Here is how you MUST measure your mileage accurately. Fill the tank and reset the odometer or write the mileage in your log book. The NEXT time you buy gas, fill the tank and divide the miles travelled by the amount of gas you buy. The result will ALWAYS be the miles per gallon you travel. There is no need to wait for the tank to be empty. You can drive 100 miles then fill the tank, or you can drive until the tank is empty then fill it. The mileage will be the same either way, assuming the same type of driving style throughout the distance travelled. You can not determine fuel mileage by watching the gas guage, and the fuel pump has no bearing on the fuel economy.

Reply to
Jeff Strickland

Dude! first of all, this is not the second time you've seen this post. Also, I know how to calculate mpg! Please read the post correctly. Thanks for your response.

Reply to
mezzodock

You're welcome.

This IS the second time I've seen the post, and there is no possible way the fuel pump can cause the problem you are reporting.

Reply to
Jeff Strickland

None of my business, but I find that there's something you can use in that post. But there's not much I can use in your response. Why did you respond? What could your response possibly help? Just in case you lack thinking skills, I'll tell you: nothing. You would have been much smarter to keep silent and see if you get any more answers, rather than to bitch about a perfectly good response. Just shut up and see if you get any more that you can use.

Like this for instance: It could certainly be the fuel pressure. If the fuel pressure's too high, obviously you'd get too much fuel, especially open loop. Surely somebody agreed with you on that. I think if your o2 sensor was right on, your van would correct itself at full operating tempearture, but not when it's cold. The pump doesn't really control fuel pressure - it's controlled by a regulator. The pump still has a role to play, though. Changing it could have made a difference. Probably did.

You'd have to be a pretty big moron to drop the tank before you measure your fuel pressure, but I admit morons post on usenet all the time. It might even be mostly morons for all I know. You can get a good fuel pressure gauge at advance auto for about $30. It's really handy, go ahead and buy it. Keep it. See if you can get somebody nice to tell you what the pressure is supposed to be.

Another thing it could be is that your van suddently stopped going closed loop. There are a dozen reasons for that. The 02 sensor is drifting rich all the time, but that's a gradual process. If you last measured your gas mileage in 2002, maybe that's it. Another thing it could be is that you never got 20 mpg in the first place. Seems possible, but that's pretty high.

Reply to
Joe

Assuming the rest of the fuel system is working properly, a new fuel pump will not alter fuel consumption. That said, you may want to check your fuel pressure regulator. If it was bad before and the fuel pump was low delivery, the pressure may have been low enough to use less fuel although producing less power output. Now that you have installed a pump with proper capacity, a bad fuel pressure regulator may be resulting in excess pressure and excess fuel consumption. That said, if you were getting 20 mpg on the highway and anything better than 14 mpg in town with that setup, it was very unusual as the 300 was known for it's ability to pull off the bottom end - not fuel economy which easily bettered by the 5.0L V8. Another thing you may want to check is the catalytic converter as they are often damaged and partially melted when a fuel pump goes south causing too much back pressure which will destroy fuel mileage and performance. Most good muffler shops can check this for you.

Lugnut

Reply to
lugnut

On Sun, 28 May 2006 16:13:44 -0700, snipped-for-privacy@aol.com rearranged some electrons to form:

Dude, does this post ring a bell?

...

You THINK you tested your mileage? Well, did you or didn't you? How did you do it?

I think we found the problem. You never actually got 20 mpg, you just think you did. I would say that there's nothing wrong with your truck, except maybe the loose nut behind the steering wheel.

If you want people to help you, don't be such a smartass. This isn't AOL, dude.

Reply to
David M

The increase in ethanol in the fuel supply is crapping out the fuel economy of most vehicles. I used to get two weeks out of a tank of gas until they started adding ethanol to it. Now I get three fewer days out of a tank. This is a real world test, I fill the tank every time and drive the same amount miles every day to and from work. The type and model is irrelevant to my response.

Reply to
TM

Just for my own curiosity, and I know this doesn't help, but this statement intrigues me. Is the above true? I would think that a fuel pump has nothing to do with the fuel gauge. In other words, in layman's terms, that the gas gauge is just going to read what the float in the tank says is in there, and would not keep the gauge at full until 27 gallons is reached. I would understand it better if he said the gauge was calibrated for 27 gallons on a 35 tank, but not the fuel pump. The fuel pump should be calibrated only in the sense that it knows how much fuel to deliver to a particular engine (eg pressure) it's installed on. Am I wrong here?

Reply to
IYM

The fuel pump assembly is not just a fuel pump, it also includes the fuel level sensor (and a check valve and a filter sock).

Ed

Reply to
C. E. White

Ah, I see. I haven't had to replace one in a very long time, so I was still going on my memory of the last one I changed on a Chevy 350, which was a mechanical pump. (had the arm on it that you inserted into the block). I assumed an electronic version was this minus the mechanical aspect. Guess they're packing a whole bunch of crap into it now. Thanks for the update!

Scott

Reply to
IYM

Okay, so I'm late and catching up, but "TM" snipped-for-privacy@hotmail.com.com>

wrote on Mon, 29 May 2006 22:56:42 GMT in alt.trucks.ford :

Alcohol doesn't have the "mpg" that gasoline has; more has to be burned to get the same effect.

Reply to
pyotr filipivich

I find this very hard to believe, even with the 300 six. That's better than a Jeep Cherokee with a smaller six-banger.

Is it possible that a wrong fuel pump can cause a

No.

Reply to
Matt Macchiarolo

I have a '94 Cherokee that had 92,000 miles on it when I bought it from the Forest Service. Yep - it's THAT color green. ;)

With that 4.0L straight six I have gotten as much as just over 25 mpg in pure highway driving. In the summer, btw.

Average for pure highway miles is about 22-23 and I get anywhere between 17-22 for mixed driving. Also, ALL my driving includes 3-1/2 miles of gravel road between my house and the highway.

Reply to
sti4667

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.